Commit 486088bc authored by Linus Torvalds's avatar Linus Torvalds

Merge tag 'standardize-docs' of git://git.lwn.net/linux

Pull documentation format standardization from Jonathan Corbet:
 "This series converts a number of top-level documents to the RST format
  without incorporating them into the Sphinx tree. The hope is to bring
  some uniformity to kernel documentation and, perhaps more importantly,
  have our existing docs serve as an example of the desired formatting
  for those that will be added later.

  Mauro has gone through and fixed up a lot of top-level documentation
  files to make them conform to the RST format, but without moving or
  renaming them in any way. This will help when we incorporate the ones
  we want to keep into the Sphinx doctree, but the real purpose is to
  bring a bit of uniformity to our documentation and let the top-level
  docs serve as examples for those writing new ones"

* tag 'standardize-docs' of git://git.lwn.net/linux: (84 commits)
  docs: kprobes.txt: Fix whitespacing
  tee.txt: standardize document format
  cgroup-v2.txt: standardize document format
  dell_rbu.txt: standardize document format
  zorro.txt: standardize document format
  xz.txt: standardize document format
  xillybus.txt: standardize document format
  vfio.txt: standardize document format
  vfio-mediated-device.txt: standardize document format
  unaligned-memory-access.txt: standardize document format
  this_cpu_ops.txt: standardize document format
  svga.txt: standardize document format
  static-keys.txt: standardize document format
  smsc_ece1099.txt: standardize document format
  SM501.txt: standardize document format
  siphash.txt: standardize document format
  sgi-ioc4.txt: standardize document format
  SAK.txt: standardize document format
  rpmsg.txt: standardize document format
  robust-futexes.txt: standardize document format
  ...
parents 52f6c588 43e5f7e1
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DMA with ISA and LPC devices
============================
============================
DMA with ISA and LPC devices
============================
Pierre Ossman <drzeus@drzeus.cx>
:Author: Pierre Ossman <drzeus@drzeus.cx>
This document describes how to do DMA transfers using the old ISA DMA
controller. Even though ISA is more or less dead today the LPC bus
uses the same DMA system so it will be around for quite some time.
Part I - Headers and dependencies
---------------------------------
Headers and dependencies
------------------------
To do ISA style DMA you need to include two headers:
To do ISA style DMA you need to include two headers::
#include <linux/dma-mapping.h>
#include <asm/dma.h>
#include <linux/dma-mapping.h>
#include <asm/dma.h>
The first is the generic DMA API used to convert virtual addresses to
bus addresses (see Documentation/DMA-API.txt for details).
......@@ -23,8 +24,8 @@ this is not present on all platforms make sure you construct your
Kconfig to be dependent on ISA_DMA_API (not ISA) so that nobody tries
to build your driver on unsupported platforms.
Part II - Buffer allocation
---------------------------
Buffer allocation
-----------------
The ISA DMA controller has some very strict requirements on which
memory it can access so extra care must be taken when allocating
......@@ -47,8 +48,8 @@ __GFP_RETRY_MAYFAIL and __GFP_NOWARN to make the allocator try a bit harder.
(This scarcity also means that you should allocate the buffer as
early as possible and not release it until the driver is unloaded.)
Part III - Address translation
------------------------------
Address translation
-------------------
To translate the virtual address to a bus address, use the normal DMA
API. Do _not_ use isa_virt_to_phys() even though it does the same
......@@ -61,8 +62,8 @@ Note: x86_64 had a broken DMA API when it came to ISA but has since
been fixed. If your arch has problems then fix the DMA API instead of
reverting to the ISA functions.
Part IV - Channels
------------------
Channels
--------
A normal ISA DMA controller has 8 channels. The lower four are for
8-bit transfers and the upper four are for 16-bit transfers.
......@@ -80,8 +81,8 @@ The ability to use 16-bit or 8-bit transfers is _not_ up to you as a
driver author but depends on what the hardware supports. Check your
specs or test different channels.
Part V - Transfer data
----------------------
Transfer data
-------------
Now for the good stuff, the actual DMA transfer. :)
......@@ -112,37 +113,37 @@ Once the DMA transfer is finished (or timed out) you should disable
the channel again. You should also check get_dma_residue() to make
sure that all data has been transferred.
Example:
Example::
int flags, residue;
int flags, residue;
flags = claim_dma_lock();
flags = claim_dma_lock();
clear_dma_ff();
clear_dma_ff();
set_dma_mode(channel, DMA_MODE_WRITE);
set_dma_addr(channel, phys_addr);
set_dma_count(channel, num_bytes);
set_dma_mode(channel, DMA_MODE_WRITE);
set_dma_addr(channel, phys_addr);
set_dma_count(channel, num_bytes);
dma_enable(channel);
dma_enable(channel);
release_dma_lock(flags);
release_dma_lock(flags);
while (!device_done());
while (!device_done());
flags = claim_dma_lock();
flags = claim_dma_lock();
dma_disable(channel);
dma_disable(channel);
residue = dma_get_residue(channel);
if (residue != 0)
printk(KERN_ERR "driver: Incomplete DMA transfer!"
" %d bytes left!\n", residue);
residue = dma_get_residue(channel);
if (residue != 0)
printk(KERN_ERR "driver: Incomplete DMA transfer!"
" %d bytes left!\n", residue);
release_dma_lock(flags);
release_dma_lock(flags);
Part VI - Suspend/resume
------------------------
Suspend/resume
--------------
It is the driver's responsibility to make sure that the machine isn't
suspended while a DMA transfer is in progress. Also, all DMA settings
......
DMA attributes
==============
==============
DMA attributes
==============
This document describes the semantics of the DMA attributes that are
defined in linux/dma-mapping.h.
......@@ -108,6 +109,7 @@ This is a hint to the DMA-mapping subsystem that it's probably not worth
the time to try to allocate memory to in a way that gives better TLB
efficiency (AKA it's not worth trying to build the mapping out of larger
pages). You might want to specify this if:
- You know that the accesses to this memory won't thrash the TLB.
You might know that the accesses are likely to be sequential or
that they aren't sequential but it's unlikely you'll ping-pong
......@@ -121,11 +123,12 @@ pages). You might want to specify this if:
the mapping to have a short lifetime then it may be worth it to
optimize allocation (avoid coming up with large pages) instead of
getting the slight performance win of larger pages.
Setting this hint doesn't guarantee that you won't get huge pages, but it
means that we won't try quite as hard to get them.
NOTE: At the moment DMA_ATTR_ALLOC_SINGLE_PAGES is only implemented on ARM,
though ARM64 patches will likely be posted soon.
.. note:: At the moment DMA_ATTR_ALLOC_SINGLE_PAGES is only implemented on ARM,
though ARM64 patches will likely be posted soon.
DMA_ATTR_NO_WARN
----------------
......@@ -142,10 +145,10 @@ problem at all, depending on the implementation of the retry mechanism.
So, this provides a way for drivers to avoid those error messages on calls
where allocation failures are not a problem, and shouldn't bother the logs.
NOTE: At the moment DMA_ATTR_NO_WARN is only implemented on PowerPC.
.. note:: At the moment DMA_ATTR_NO_WARN is only implemented on PowerPC.
DMA_ATTR_PRIVILEGED
------------------------------
-------------------
Some advanced peripherals such as remote processors and GPUs perform
accesses to DMA buffers in both privileged "supervisor" and unprivileged
......
=====================
The Linux IPMI Driver
=====================
The Linux IPMI Driver
---------------------
Corey Minyard
<minyard@mvista.com>
<minyard@acm.org>
:Author: Corey Minyard <minyard@mvista.com> / <minyard@acm.org>
The Intelligent Platform Management Interface, or IPMI, is a
standard for controlling intelligent devices that monitor a system.
......@@ -141,7 +140,7 @@ Addressing
----------
The IPMI addressing works much like IP addresses, you have an overlay
to handle the different address types. The overlay is:
to handle the different address types. The overlay is::
struct ipmi_addr
{
......@@ -153,7 +152,7 @@ to handle the different address types. The overlay is:
The addr_type determines what the address really is. The driver
currently understands two different types of addresses.
"System Interface" addresses are defined as:
"System Interface" addresses are defined as::
struct ipmi_system_interface_addr
{
......@@ -166,7 +165,7 @@ straight to the BMC on the current card. The channel must be
IPMI_BMC_CHANNEL.
Messages that are destined to go out on the IPMB bus use the
IPMI_IPMB_ADDR_TYPE address type. The format is
IPMI_IPMB_ADDR_TYPE address type. The format is::
struct ipmi_ipmb_addr
{
......@@ -184,16 +183,16 @@ spec.
Messages
--------
Messages are defined as:
Messages are defined as::
struct ipmi_msg
{
struct ipmi_msg
{
unsigned char netfn;
unsigned char lun;
unsigned char cmd;
unsigned char *data;
int data_len;
};
};
The driver takes care of adding/stripping the header information. The
data portion is just the data to be send (do NOT put addressing info
......@@ -208,7 +207,7 @@ block of data, even when receiving messages. Otherwise the driver
will have no place to put the message.
Messages coming up from the message handler in kernelland will come in
as:
as::
struct ipmi_recv_msg
{
......@@ -246,6 +245,7 @@ and the user should not have to care what type of SMI is below them.
Watching For Interfaces
^^^^^^^^^^^^^^^^^^^^^^^
When your code comes up, the IPMI driver may or may not have detected
if IPMI devices exist. So you might have to defer your setup until
......@@ -256,6 +256,7 @@ and tell you when they come and go.
Creating the User
^^^^^^^^^^^^^^^^^
To use the message handler, you must first create a user using
ipmi_create_user. The interface number specifies which SMI you want
......@@ -272,6 +273,7 @@ closing the device automatically destroys the user.
Messaging
^^^^^^^^^
To send a message from kernel-land, the ipmi_request_settime() call does
pretty much all message handling. Most of the parameter are
......@@ -321,6 +323,7 @@ though, since it is tricky to manage your own buffers.
Events and Incoming Commands
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The driver takes care of polling for IPMI events and receiving
commands (commands are messages that are not responses, they are
......@@ -367,7 +370,7 @@ in the system. It discovers interfaces through a host of different
methods, depending on the system.
You can specify up to four interfaces on the module load line and
control some module parameters:
control some module parameters::
modprobe ipmi_si.o type=<type1>,<type2>....
ports=<port1>,<port2>... addrs=<addr1>,<addr2>...
......@@ -437,7 +440,7 @@ default is one. Setting to 0 is useful with the hotmod, but is
obviously only useful for modules.
When compiled into the kernel, the parameters can be specified on the
kernel command line as:
kernel command line as::
ipmi_si.type=<type1>,<type2>...
ipmi_si.ports=<port1>,<port2>... ipmi_si.addrs=<addr1>,<addr2>...
......@@ -474,16 +477,22 @@ The driver supports a hot add and remove of interfaces. This way,
interfaces can be added or removed after the kernel is up and running.
This is done using /sys/modules/ipmi_si/parameters/hotmod, which is a
write-only parameter. You write a string to this interface. The string
has the format:
has the format::
<op1>[:op2[:op3...]]
The "op"s are:
The "op"s are::
add|remove,kcs|bt|smic,mem|i/o,<address>[,<opt1>[,<opt2>[,...]]]
You can specify more than one interface on the line. The "opt"s are:
You can specify more than one interface on the line. The "opt"s are::
rsp=<regspacing>
rsi=<regsize>
rsh=<regshift>
irq=<irq>
ipmb=<ipmb slave addr>
and these have the same meanings as discussed above. Note that you
can also use this on the kernel command line for a more compact format
for specifying an interface. Note that when removing an interface,
......@@ -496,7 +505,7 @@ The SMBus Driver (SSIF)
The SMBus driver allows up to 4 SMBus devices to be configured in the
system. By default, the driver will only register with something it
finds in DMI or ACPI tables. You can change this
at module load time (for a module) with:
at module load time (for a module) with::
modprobe ipmi_ssif.o
addr=<i2caddr1>[,<i2caddr2>[,...]]
......@@ -535,7 +544,7 @@ the smb_addr parameter unless you have DMI or ACPI data to tell the
driver what to use.
When compiled into the kernel, the addresses can be specified on the
kernel command line as:
kernel command line as::
ipmb_ssif.addr=<i2caddr1>[,<i2caddr2>[...]]
ipmi_ssif.adapter=<adapter1>[,<adapter2>[...]]
......@@ -565,9 +574,9 @@ Some users need more detailed information about a device, like where
the address came from or the raw base device for the IPMI interface.
You can use the IPMI smi_watcher to catch the IPMI interfaces as they
come or go, and to grab the information, you can use the function
ipmi_get_smi_info(), which returns the following structure:
ipmi_get_smi_info(), which returns the following structure::
struct ipmi_smi_info {
struct ipmi_smi_info {
enum ipmi_addr_src addr_src;
struct device *dev;
union {
......@@ -575,7 +584,7 @@ struct ipmi_smi_info {
void *acpi_handle;
} acpi_info;
} addr_info;
};
};
Currently special info for only for SI_ACPI address sources is
returned. Others may be added as necessary.
......@@ -590,7 +599,7 @@ Watchdog
A watchdog timer is provided that implements the Linux-standard
watchdog timer interface. It has three module parameters that can be
used to control it:
used to control it::
modprobe ipmi_watchdog timeout=<t> pretimeout=<t> action=<action type>
preaction=<preaction type> preop=<preop type> start_now=x
......@@ -635,7 +644,7 @@ watchdog device is closed. The default value of nowayout is true
if the CONFIG_WATCHDOG_NOWAYOUT option is enabled, or false if not.
When compiled into the kernel, the kernel command line is available
for configuring the watchdog:
for configuring the watchdog::
ipmi_watchdog.timeout=<t> ipmi_watchdog.pretimeout=<t>
ipmi_watchdog.action=<action type>
......@@ -675,6 +684,7 @@ also get a bunch of OEM events holding the panic string.
The field settings of the events are:
* Generator ID: 0x21 (kernel)
* EvM Rev: 0x03 (this event is formatting in IPMI 1.0 format)
* Sensor Type: 0x20 (OS critical stop sensor)
......@@ -683,18 +693,20 @@ The field settings of the events are:
* Event Data 1: 0xa1 (Runtime stop in OEM bytes 2 and 3)
* Event data 2: second byte of panic string
* Event data 3: third byte of panic string
See the IPMI spec for the details of the event layout. This event is
always sent to the local management controller. It will handle routing
the message to the right place
Other OEM events have the following format:
Record ID (bytes 0-1): Set by the SEL.
Record type (byte 2): 0xf0 (OEM non-timestamped)
byte 3: The slave address of the card saving the panic
byte 4: A sequence number (starting at zero)
The rest of the bytes (11 bytes) are the panic string. If the panic string
is longer than 11 bytes, multiple messages will be sent with increasing
sequence numbers.
* Record ID (bytes 0-1): Set by the SEL.
* Record type (byte 2): 0xf0 (OEM non-timestamped)
* byte 3: The slave address of the card saving the panic
* byte 4: A sequence number (starting at zero)
The rest of the bytes (11 bytes) are the panic string. If the panic string
is longer than 11 bytes, multiple messages will be sent with increasing
sequence numbers.
Because you cannot send OEM events using the standard interface, this
function will attempt to find an SEL and add the events there. It
......
================
SMP IRQ affinity
================
ChangeLog:
Started by Ingo Molnar <mingo@redhat.com>
Update by Max Krasnyansky <maxk@qualcomm.com>
- Started by Ingo Molnar <mingo@redhat.com>
- Update by Max Krasnyansky <maxk@qualcomm.com>
SMP IRQ affinity
/proc/irq/IRQ#/smp_affinity and /proc/irq/IRQ#/smp_affinity_list specify
which target CPUs are permitted for a given IRQ source. It's a bitmask
......@@ -16,50 +19,52 @@ will be set to the default mask. It can then be changed as described above.
Default mask is 0xffffffff.
Here is an example of restricting IRQ44 (eth1) to CPU0-3 then restricting
it to CPU4-7 (this is an 8-CPU SMP box):
it to CPU4-7 (this is an 8-CPU SMP box)::
[root@moon 44]# cd /proc/irq/44
[root@moon 44]# cat smp_affinity
ffffffff
[root@moon 44]# cd /proc/irq/44
[root@moon 44]# cat smp_affinity
ffffffff
[root@moon 44]# echo 0f > smp_affinity
[root@moon 44]# cat smp_affinity
0000000f
[root@moon 44]# ping -f h
PING hell (195.4.7.3): 56 data bytes
...
--- hell ping statistics ---
6029 packets transmitted, 6027 packets received, 0% packet loss
round-trip min/avg/max = 0.1/0.1/0.4 ms
[root@moon 44]# cat /proc/interrupts | grep 'CPU\|44:'
CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7
44: 1068 1785 1785 1783 0 0 0 0 IO-APIC-level eth1
[root@moon 44]# echo 0f > smp_affinity
[root@moon 44]# cat smp_affinity
0000000f
[root@moon 44]# ping -f h
PING hell (195.4.7.3): 56 data bytes
...
--- hell ping statistics ---
6029 packets transmitted, 6027 packets received, 0% packet loss
round-trip min/avg/max = 0.1/0.1/0.4 ms
[root@moon 44]# cat /proc/interrupts | grep 'CPU\|44:'
CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7
44: 1068 1785 1785 1783 0 0 0 0 IO-APIC-level eth1
As can be seen from the line above IRQ44 was delivered only to the first four
processors (0-3).
Now lets restrict that IRQ to CPU(4-7).
[root@moon 44]# echo f0 > smp_affinity
[root@moon 44]# cat smp_affinity
000000f0
[root@moon 44]# ping -f h
PING hell (195.4.7.3): 56 data bytes
..
--- hell ping statistics ---
2779 packets transmitted, 2777 packets received, 0% packet loss
round-trip min/avg/max = 0.1/0.5/585.4 ms
[root@moon 44]# cat /proc/interrupts | 'CPU\|44:'
CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7
44: 1068 1785 1785 1783 1784 1069 1070 1069 IO-APIC-level eth1
::
[root@moon 44]# echo f0 > smp_affinity
[root@moon 44]# cat smp_affinity
000000f0
[root@moon 44]# ping -f h
PING hell (195.4.7.3): 56 data bytes
..
--- hell ping statistics ---
2779 packets transmitted, 2777 packets received, 0% packet loss
round-trip min/avg/max = 0.1/0.5/585.4 ms
[root@moon 44]# cat /proc/interrupts | 'CPU\|44:'
CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7
44: 1068 1785 1785 1783 1784 1069 1070 1069 IO-APIC-level eth1
This time around IRQ44 was delivered only to the last four processors.
i.e counters for the CPU0-3 did not change.
Here is an example of limiting that same irq (44) to cpus 1024 to 1031:
Here is an example of limiting that same irq (44) to cpus 1024 to 1031::
[root@moon 44]# echo 1024-1031 > smp_affinity_list
[root@moon 44]# cat smp_affinity_list
1024-1031
[root@moon 44]# echo 1024-1031 > smp_affinity_list
[root@moon 44]# cat smp_affinity_list
1024-1031
Note that to do this with a bitmask would require 32 bitmasks of zero
to follow the pertinent one.
irq_domain interrupt number mapping library
===============================================
The irq_domain interrupt number mapping library
===============================================
The current design of the Linux kernel uses a single large number
space where each separate IRQ source is assigned a different number.
......@@ -36,7 +38,9 @@ irq_domain also implements translation from an abstract irq_fwspec
structure to hwirq numbers (Device Tree and ACPI GSI so far), and can
be easily extended to support other IRQ topology data sources.
=== irq_domain usage ===
irq_domain usage
================
An interrupt controller driver creates and registers an irq_domain by
calling one of the irq_domain_add_*() functions (each mapping method
has a different allocator function, more on that later). The function
......@@ -62,15 +66,21 @@ If the driver has the Linux IRQ number or the irq_data pointer, and
needs to know the associated hwirq number (such as in the irq_chip
callbacks) then it can be directly obtained from irq_data->hwirq.
=== Types of irq_domain mappings ===
Types of irq_domain mappings
============================
There are several mechanisms available for reverse mapping from hwirq
to Linux irq, and each mechanism uses a different allocation function.
Which reverse map type should be used depends on the use case. Each
of the reverse map types are described below:
==== Linear ====
irq_domain_add_linear()
irq_domain_create_linear()
Linear
------
::
irq_domain_add_linear()
irq_domain_create_linear()
The linear reverse map maintains a fixed size table indexed by the
hwirq number. When a hwirq is mapped, an irq_desc is allocated for
......@@ -89,9 +99,13 @@ accepts a more general abstraction 'struct fwnode_handle'.
The majority of drivers should use the linear map.
==== Tree ====
irq_domain_add_tree()
irq_domain_create_tree()
Tree
----
::
irq_domain_add_tree()
irq_domain_create_tree()
The irq_domain maintains a radix tree map from hwirq numbers to Linux
IRQs. When an hwirq is mapped, an irq_desc is allocated and the
......@@ -109,8 +123,12 @@ accepts a more general abstraction 'struct fwnode_handle'.
Very few drivers should need this mapping.
==== No Map ===-
irq_domain_add_nomap()
No Map
------
::
irq_domain_add_nomap()
The No Map mapping is to be used when the hwirq number is
programmable in the hardware. In this case it is best to program the
......@@ -121,10 +139,14 @@ Linux IRQ number into the hardware.
Most drivers cannot use this mapping.
==== Legacy ====
irq_domain_add_simple()
irq_domain_add_legacy()
irq_domain_add_legacy_isa()
Legacy
------
::
irq_domain_add_simple()
irq_domain_add_legacy()
irq_domain_add_legacy_isa()
The Legacy mapping is a special case for drivers that already have a
range of irq_descs allocated for the hwirqs. It is used when the
......@@ -163,14 +185,17 @@ that the driver using the simple domain call irq_create_mapping()
before any irq_find_mapping() since the latter will actually work
for the static IRQ assignment case.
==== Hierarchy IRQ domain ====
Hierarchy IRQ domain
--------------------
On some architectures, there may be multiple interrupt controllers
involved in delivering an interrupt from the device to the target CPU.
Let's look at a typical interrupt delivering path on x86 platforms:
Let's look at a typical interrupt delivering path on x86 platforms::
Device --> IOAPIC -> Interrupt remapping Controller -> Local APIC -> CPU
Device --> IOAPIC -> Interrupt remapping Controller -> Local APIC -> CPU
There are three interrupt controllers involved:
1) IOAPIC controller
2) Interrupt remapping controller
3) Local APIC controller
......@@ -180,7 +205,8 @@ hardware architecture, an irq_domain data structure is built for each
interrupt controller and those irq_domains are organized into hierarchy.
When building irq_domain hierarchy, the irq_domain near to the device is
child and the irq_domain near to CPU is parent. So a hierarchy structure
as below will be built for the example above.
as below will be built for the example above::
CPU Vector irq_domain (root irq_domain to manage CPU vectors)
^
|
......@@ -190,6 +216,7 @@ as below will be built for the example above.
IOAPIC irq_domain (manage IOAPIC delivery entries/pins)
There are four major interfaces to use hierarchy irq_domain:
1) irq_domain_alloc_irqs(): allocate IRQ descriptors and interrupt
controller related resources to deliver these interrupts.
2) irq_domain_free_irqs(): free IRQ descriptors and interrupt controller
......@@ -199,7 +226,8 @@ There are four major interfaces to use hierarchy irq_domain:
4) irq_domain_deactivate_irq(): deactivate interrupt controller hardware
to stop delivering the interrupt.
Following changes are needed to support hierarchy irq_domain.
Following changes are needed to support hierarchy irq_domain:
1) a new field 'parent' is added to struct irq_domain; it's used to
maintain irq_domain hierarchy information.
2) a new field 'parent_data' is added to struct irq_data; it's used to
......@@ -223,6 +251,7 @@ software architecture.
For an interrupt controller driver to support hierarchy irq_domain, it
needs to:
1) Implement irq_domain_ops.alloc and irq_domain_ops.free
2) Optionally implement irq_domain_ops.activate and
irq_domain_ops.deactivate.
......
===============
What is an IRQ?
===============
An IRQ is an interrupt request from a device.
Currently they can come in over a pin, or over a packet.
......
===================
Linux IOMMU Support
===================
......@@ -9,11 +10,11 @@ This guide gives a quick cheat sheet for some basic understanding.
Some Keywords
DMAR - DMA remapping
DRHD - DMA Remapping Hardware Unit Definition
RMRR - Reserved memory Region Reporting Structure
ZLR - Zero length reads from PCI devices
IOVA - IO Virtual address.
- DMAR - DMA remapping
- DRHD - DMA Remapping Hardware Unit Definition
- RMRR - Reserved memory Region Reporting Structure
- ZLR - Zero length reads from PCI devices
- IOVA - IO Virtual address.
Basic stuff
-----------
......@@ -33,7 +34,7 @@ devices that need to access these regions. OS is expected to setup
unity mappings for these regions for these devices to access these regions.
How is IOVA generated?
---------------------
----------------------
Well behaved drivers call pci_map_*() calls before sending command to device
that needs to perform DMA. Once DMA is completed and mapping is no longer
......@@ -82,14 +83,14 @@ in ACPI.
ACPI: DMAR (v001 A M I OEMDMAR 0x00000001 MSFT 0x00000097) @ 0x000000007f5b5ef0
When DMAR is being processed and initialized by ACPI, prints DMAR locations
and any RMRR's processed.
and any RMRR's processed::
ACPI DMAR:Host address width 36
ACPI DMAR:DRHD (flags: 0x00000000)base: 0x00000000fed90000
ACPI DMAR:DRHD (flags: 0x00000000)base: 0x00000000fed91000
ACPI DMAR:DRHD (flags: 0x00000001)base: 0x00000000fed93000
ACPI DMAR:RMRR base: 0x00000000000ed000 end: 0x00000000000effff
ACPI DMAR:RMRR base: 0x000000007f600000 end: 0x000000007fffffff
ACPI DMAR:Host address width 36
ACPI DMAR:DRHD (flags: 0x00000000)base: 0x00000000fed90000
ACPI DMAR:DRHD (flags: 0x00000000)base: 0x00000000fed91000
ACPI DMAR:DRHD (flags: 0x00000001)base: 0x00000000fed93000
ACPI DMAR:RMRR base: 0x00000000000ed000 end: 0x00000000000effff
ACPI DMAR:RMRR base: 0x000000007f600000 end: 0x000000007fffffff
When DMAR is enabled for use, you will notice..
......@@ -98,10 +99,12 @@ PCI-DMA: Using DMAR IOMMU
Fault reporting
---------------
DMAR:[DMA Write] Request device [00:02.0] fault addr 6df084000
DMAR:[fault reason 05] PTE Write access is not set
DMAR:[DMA Write] Request device [00:02.0] fault addr 6df084000
DMAR:[fault reason 05] PTE Write access is not set
::
DMAR:[DMA Write] Request device [00:02.0] fault addr 6df084000
DMAR:[fault reason 05] PTE Write access is not set
DMAR:[DMA Write] Request device [00:02.0] fault addr 6df084000
DMAR:[fault reason 05] PTE Write access is not set
TBD
----
......
Linux 2.4.2 Secure Attention Key (SAK) handling
18 March 2001, Andrew Morton
=========================================
Linux Secure Attention Key (SAK) handling
=========================================
:Date: 18 March 2001
:Author: Andrew Morton
An operating system's Secure Attention Key is a security tool which is
provided as protection against trojan password capturing programs. It
......@@ -13,7 +17,7 @@ this sequence. It is only available if the kernel was compiled with
sysrq support.
The proper way of generating a SAK is to define the key sequence using
`loadkeys'. This will work whether or not sysrq support is compiled
``loadkeys``. This will work whether or not sysrq support is compiled
into the kernel.
SAK works correctly when the keyboard is in raw mode. This means that
......@@ -25,64 +29,63 @@ What key sequence should you use? Well, CTRL-ALT-DEL is used to reboot
the machine. CTRL-ALT-BACKSPACE is magical to the X server. We'll
choose CTRL-ALT-PAUSE.
In your rc.sysinit (or rc.local) file, add the command
In your rc.sysinit (or rc.local) file, add the command::
echo "control alt keycode 101 = SAK" | /bin/loadkeys
And that's it! Only the superuser may reprogram the SAK key.
NOTES
=====
.. note::
1: Linux SAK is said to be not a "true SAK" as is required by
systems which implement C2 level security. This author does not
know why.
1. Linux SAK is said to be not a "true SAK" as is required by
systems which implement C2 level security. This author does not
know why.
2: On the PC keyboard, SAK kills all applications which have
/dev/console opened.
2. On the PC keyboard, SAK kills all applications which have
/dev/console opened.
Unfortunately this includes a number of things which you don't
actually want killed. This is because these applications are
incorrectly holding /dev/console open. Be sure to complain to your
Linux distributor about this!
Unfortunately this includes a number of things which you don't
actually want killed. This is because these applications are
incorrectly holding /dev/console open. Be sure to complain to your
Linux distributor about this!
You can identify processes which will be killed by SAK with the
command
You can identify processes which will be killed by SAK with the
command::
# ls -l /proc/[0-9]*/fd/* | grep console
l-wx------ 1 root root 64 Mar 18 00:46 /proc/579/fd/0 -> /dev/console
Then:
Then::
# ps aux|grep 579
root 579 0.0 0.1 1088 436 ? S 00:43 0:00 gpm -t ps/2
So `gpm' will be killed by SAK. This is a bug in gpm. It should
be closing standard input. You can work around this by finding the
initscript which launches gpm and changing it thusly:
So ``gpm`` will be killed by SAK. This is a bug in gpm. It should
be closing standard input. You can work around this by finding the
initscript which launches gpm and changing it thusly:
Old:
Old::
daemon gpm
New:
New::
daemon gpm < /dev/null
Vixie cron also seems to have this problem, and needs the same treatment.
Vixie cron also seems to have this problem, and needs the same treatment.
Also, one prominent Linux distribution has the following three
lines in its rc.sysinit and rc scripts:
Also, one prominent Linux distribution has the following three
lines in its rc.sysinit and rc scripts::
exec 3<&0
exec 4>&1
exec 5>&2
These commands cause *all* daemons which are launched by the
initscripts to have file descriptors 3, 4 and 5 attached to
/dev/console. So SAK kills them all. A workaround is to simply
delete these lines, but this may cause system management
applications to malfunction - test everything well.
These commands cause **all** daemons which are launched by the
initscripts to have file descriptors 3, 4 and 5 attached to
/dev/console. So SAK kills them all. A workaround is to simply
delete these lines, but this may cause system management
applications to malfunction - test everything well.
SM501 Driver
============
.. include:: <isonum.txt>
Copyright 2006, 2007 Simtec Electronics
============
SM501 Driver
============
:Copyright: |copy| 2006, 2007 Simtec Electronics
The Silicon Motion SM501 multimedia companion chip is a multifunction device
which may provide numerous interfaces including USB host controller USB gadget,
......
This diff is collapsed.
===============================================================
== BT8XXGPIO driver ==
== ==
== A driver for a selfmade cheap BT8xx based PCI GPIO-card ==
== ==
== For advanced documentation, see ==
== http://www.bu3sch.de/btgpio.php ==
===============================================================
===================================================================
A driver for a selfmade cheap BT8xx based PCI GPIO-card (bt8xxgpio)
===================================================================
For advanced documentation, see http://www.bu3sch.de/btgpio.php
A generic digital 24-port PCI GPIO card can be built out of an ordinary
Brooktree bt848, bt849, bt878 or bt879 based analog TV tuner card. The
......@@ -17,9 +13,8 @@ The bt8xx chip does have 24 digital GPIO ports.
These ports are accessible via 24 pins on the SMD chip package.
==============================================
== How to physically access the GPIO pins ==
==============================================
How to physically access the GPIO pins
======================================
The are several ways to access these pins. One might unsolder the whole chip
and put it on a custom PCI board, or one might only unsolder each individual
......@@ -27,7 +22,7 @@ GPIO pin and solder that to some tiny wire. As the chip package really is tiny
there are some advanced soldering skills needed in any case.
The physical pinouts are drawn in the following ASCII art.
The GPIO pins are marked with G00-G23
The GPIO pins are marked with G00-G23::
G G G G G G G G G G G G G G G G G G
0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
......
=======================================================================
README for btmrvl driver
=======================================================================
=============
btmrvl driver
=============
All commands are used via debugfs interface.
=====================
Set/get driver configurations:
Set/get driver configurations
=============================
Path: /debug/btmrvl/config/
gpiogap=[n]
hscfgcmd
These commands are used to configure the host sleep parameters.
gpiogap=[n], hscfgcmd
These commands are used to configure the host sleep parameters::
bit 8:0 -- Gap
bit 16:8 -- GPIO
......@@ -23,7 +21,8 @@ hscfgcmd
where Gap is the gap in milli seconds between wakeup signal and
wakeup event, or 0xff for special host sleep setting.
Usage:
Usage::
# Use SDIO interface to wake up the host and set GAP to 0x80:
echo 0xff80 > /debug/btmrvl/config/gpiogap
echo 1 > /debug/btmrvl/config/hscfgcmd
......@@ -32,15 +31,16 @@ hscfgcmd
echo 0x03ff > /debug/btmrvl/config/gpiogap
echo 1 > /debug/btmrvl/config/hscfgcmd
psmode=[n]
pscmd
psmode=[n], pscmd
These commands are used to enable/disable auto sleep mode
where the option is:
where the option is::
1 -- Enable auto sleep mode
0 -- Disable auto sleep mode
Usage:
Usage::
# Enable auto sleep mode
echo 1 > /debug/btmrvl/config/psmode
echo 1 > /debug/btmrvl/config/pscmd
......@@ -50,15 +50,16 @@ pscmd
echo 1 > /debug/btmrvl/config/pscmd
hsmode=[n]
hscmd
hsmode=[n], hscmd
These commands are used to enable host sleep or wake up firmware
where the option is:
where the option is::
1 -- Enable host sleep
0 -- Wake up firmware
Usage:
Usage::
# Enable host sleep
echo 1 > /debug/btmrvl/config/hsmode
echo 1 > /debug/btmrvl/config/hscmd
......@@ -68,12 +69,13 @@ hscmd
echo 1 > /debug/btmrvl/config/hscmd
======================
Get driver status:
Get driver status
=================
Path: /debug/btmrvl/status/
Usage:
Usage::
cat /debug/btmrvl/status/<args>
where the args are:
......@@ -90,14 +92,17 @@ hsstate
txdnldrdy
This command displays the value of Tx download ready flag.
=====================
Issuing a raw hci command
=========================
Use hcitool to issue raw hci command, refer to hcitool manual
Usage: Hcitool cmd <ogf> <ocf> [Parameters]
Usage::
Hcitool cmd <ogf> <ocf> [Parameters]
Interface Control Command::
Interface Control Command
hcitool cmd 0x3f 0x5b 0xf5 0x01 0x00 --Enable All interface
hcitool cmd 0x3f 0x5b 0xf5 0x01 0x01 --Enable Wlan interface
hcitool cmd 0x3f 0x5b 0xf5 0x01 0x02 --Enable BT interface
......@@ -105,13 +110,13 @@ Use hcitool to issue raw hci command, refer to hcitool manual
hcitool cmd 0x3f 0x5b 0xf5 0x00 0x01 --Disable Wlan interface
hcitool cmd 0x3f 0x5b 0xf5 0x00 0x02 --Disable BT interface
=======================================================================
SD8688 firmware
===============
SD8688 firmware:
Images:
/lib/firmware/sd8688_helper.bin
/lib/firmware/sd8688.bin
- /lib/firmware/sd8688_helper.bin
- /lib/firmware/sd8688.bin
The images can be downloaded from:
......
[ NOTE: The virt_to_bus() and bus_to_virt() functions have been
==========================================================
How to access I/O mapped memory from within device drivers
==========================================================
:Author: Linus
.. warning::
The virt_to_bus() and bus_to_virt() functions have been
superseded by the functionality provided by the PCI DMA interface
(see Documentation/DMA-API-HOWTO.txt). They continue
to be documented below for historical purposes, but new code
must not use them. --davidm 00/12/12 ]
must not use them. --davidm 00/12/12
[ This is a mail message in response to a query on IO mapping, thus the
strange format for a "document" ]
::
[ This is a mail message in response to a query on IO mapping, thus the
strange format for a "document" ]
The AHA-1542 is a bus-master device, and your patch makes the driver give the
controller the physical address of the buffers, which is correct on x86
(because all bus master devices see the physical memory mappings directly).
However, on many setups, there are actually _three_ different ways of looking
However, on many setups, there are actually **three** different ways of looking
at memory addresses, and in this case we actually want the third, the
so-called "bus address".
......@@ -38,7 +48,7 @@ because the memory and the devices share the same address space, and that is
not generally necessarily true on other PCI/ISA setups.
Now, just as an example, on the PReP (PowerPC Reference Platform), the
CPU sees a memory map something like this (this is from memory):
CPU sees a memory map something like this (this is from memory)::
0-2 GB "real memory"
2 GB-3 GB "system IO" (inb/out and similar accesses on x86)
......@@ -52,7 +62,7 @@ So when the CPU wants any bus master to write to physical memory 0, it
has to give the master address 0x80000000 as the memory address.
So, for example, depending on how the kernel is actually mapped on the
PPC, you can end up with a setup like this:
PPC, you can end up with a setup like this::
physical address: 0
virtual address: 0xC0000000
......@@ -61,7 +71,7 @@ PPC, you can end up with a setup like this:
where all the addresses actually point to the same thing. It's just seen
through different translations..
Similarly, on the Alpha, the normal translation is
Similarly, on the Alpha, the normal translation is::
physical address: 0
virtual address: 0xfffffc0000000000
......@@ -70,7 +80,7 @@ Similarly, on the Alpha, the normal translation is
(but there are also Alphas where the physical address and the bus address
are the same).
Anyway, the way to look up all these translations, you do
Anyway, the way to look up all these translations, you do::
#include <asm/io.h>
......@@ -81,8 +91,8 @@ Anyway, the way to look up all these translations, you do
Now, when do you need these?
You want the _virtual_ address when you are actually going to access that
pointer from the kernel. So you can have something like this:
You want the **virtual** address when you are actually going to access that
pointer from the kernel. So you can have something like this::
/*
* this is the hardware "mailbox" we use to communicate with
......@@ -104,7 +114,7 @@ pointer from the kernel. So you can have something like this:
...
on the other hand, you want the bus address when you have a buffer that
you want to give to the controller:
you want to give to the controller::
/* ask the controller to read the sense status into "sense_buffer" */
mbox.bufstart = virt_to_bus(&sense_buffer);
......@@ -112,7 +122,7 @@ you want to give to the controller:
mbox.status = 0;
notify_controller(&mbox);
And you generally _never_ want to use the physical address, because you can't
And you generally **never** want to use the physical address, because you can't
use that from the CPU (the CPU only uses translated virtual addresses), and
you can't use it from the bus master.
......@@ -124,8 +134,10 @@ be remapped as measured in units of pages, a.k.a. the pfn (the memory
management layer doesn't know about devices outside the CPU, so it
shouldn't need to know about "bus addresses" etc).
NOTE NOTE NOTE! The above is only one part of the whole equation. The above
only talks about "real memory", that is, CPU memory (RAM).
.. note::
The above is only one part of the whole equation. The above
only talks about "real memory", that is, CPU memory (RAM).
There is a completely different type of memory too, and that's the "shared
memory" on the PCI or ISA bus. That's generally not RAM (although in the case
......@@ -137,20 +149,22 @@ whatever, and there is only one way to access it: the readb/writeb and
related functions. You should never take the address of such memory, because
there is really nothing you can do with such an address: it's not
conceptually in the same memory space as "real memory" at all, so you cannot
just dereference a pointer. (Sadly, on x86 it _is_ in the same memory space,
just dereference a pointer. (Sadly, on x86 it **is** in the same memory space,
so on x86 it actually works to just deference a pointer, but it's not
portable).
For such memory, you can do things like
For such memory, you can do things like:
- reading::
- reading:
/*
* read first 32 bits from ISA memory at 0xC0000, aka
* C000:0000 in DOS terms
*/
unsigned int signature = isa_readl(0xC0000);
- remapping and writing:
- remapping and writing::
/*
* remap framebuffer PCI memory area at 0xFC000000,
* size 1MB, so that we can access it: We can directly
......@@ -165,7 +179,8 @@ For such memory, you can do things like
/* unmap when we unload the driver */
iounmap(baseptr);
- copying and clearing:
- copying and clearing::
/* get the 6-byte Ethernet address at ISA address E000:0040 */
memcpy_fromio(kernel_buffer, 0xE0040, 6);
/* write a packet to the driver */
......@@ -181,10 +196,10 @@ happy that your driver works ;)
Note that kernel versions 2.0.x (and earlier) mistakenly called the
ioremap() function "vremap()". ioremap() is the proper name, but I
didn't think straight when I wrote it originally. People who have to
support both can do something like:
support both can do something like::
/* support old naming silliness */
#if LINUX_VERSION_CODE < 0x020100
#if LINUX_VERSION_CODE < 0x020100
#define ioremap vremap
#define iounmap vfree
#endif
......@@ -196,13 +211,10 @@ And the above sounds worse than it really is. Most real drivers really
don't do all that complex things (or rather: the complexity is not so
much in the actual IO accesses as in error handling and timeouts etc).
It's generally not hard to fix drivers, and in many cases the code
actually looks better afterwards:
actually looks better afterwards::
unsigned long signature = *(unsigned int *) 0xC0000;
vs
unsigned long signature = readl(0xC0000);
I think the second version actually is more readable, no?
Linus
This diff is collapsed.
This diff is collapsed.
================
CIRCULAR BUFFERS
================
================
Circular Buffers
================
By: David Howells <dhowells@redhat.com>
Paul E. McKenney <paulmck@linux.vnet.ibm.com>
:Author: David Howells <dhowells@redhat.com>
:Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Linux provides a number of features that can be used to implement circular
......@@ -20,7 +20,7 @@ producer and just one consumer. It is possible to handle multiple producers by
serialising them, and to handle multiple consumers by serialising them.
Contents:
.. Contents:
(*) What is a circular buffer?
......@@ -31,8 +31,8 @@ Contents:
- The consumer.
==========================
WHAT IS A CIRCULAR BUFFER?
What is a circular buffer?
==========================
First of all, what is a circular buffer? A circular buffer is a buffer of
......@@ -60,9 +60,7 @@ buffer, provided that neither index overtakes the other. The implementer must
be careful, however, as a region more than one unit in size may wrap the end of
the buffer and be broken into two segments.
============================
MEASURING POWER-OF-2 BUFFERS
Measuring power-of-2 buffers
============================
Calculation of the occupancy or the remaining capacity of an arbitrarily sized
......@@ -71,13 +69,13 @@ modulus (divide) instruction. However, if the buffer is of a power-of-2 size,
then a much quicker bitwise-AND instruction can be used instead.
Linux provides a set of macros for handling power-of-2 circular buffers. These
can be made use of by:
can be made use of by::
#include <linux/circ_buf.h>
The macros are:
(*) Measure the remaining capacity of a buffer:
(#) Measure the remaining capacity of a buffer::
CIRC_SPACE(head_index, tail_index, buffer_size);
......@@ -85,7 +83,7 @@ The macros are:
can be inserted.
(*) Measure the maximum consecutive immediate space in a buffer:
(#) Measure the maximum consecutive immediate space in a buffer::
CIRC_SPACE_TO_END(head_index, tail_index, buffer_size);
......@@ -94,14 +92,14 @@ The macros are:
beginning of the buffer.
(*) Measure the occupancy of a buffer:
(#) Measure the occupancy of a buffer::
CIRC_CNT(head_index, tail_index, buffer_size);
This returns the number of items currently occupying a buffer[2].
(*) Measure the non-wrapping occupancy of a buffer:
(#) Measure the non-wrapping occupancy of a buffer::
CIRC_CNT_TO_END(head_index, tail_index, buffer_size);
......@@ -112,7 +110,7 @@ The macros are:
Each of these macros will nominally return a value between 0 and buffer_size-1,
however:
[1] CIRC_SPACE*() are intended to be used in the producer. To the producer
(1) CIRC_SPACE*() are intended to be used in the producer. To the producer
they will return a lower bound as the producer controls the head index,
but the consumer may still be depleting the buffer on another CPU and
moving the tail index.
......@@ -120,7 +118,7 @@ however:
To the consumer it will show an upper bound as the producer may be busy
depleting the space.
[2] CIRC_CNT*() are intended to be used in the consumer. To the consumer they
(2) CIRC_CNT*() are intended to be used in the consumer. To the consumer they
will return a lower bound as the consumer controls the tail index, but the
producer may still be filling the buffer on another CPU and moving the
head index.
......@@ -128,14 +126,12 @@ however:
To the producer it will show an upper bound as the consumer may be busy
emptying the buffer.
[3] To a third party, the order in which the writes to the indices by the
(3) To a third party, the order in which the writes to the indices by the
producer and consumer become visible cannot be guaranteed as they are
independent and may be made on different CPUs - so the result in such a
situation will merely be a guess, and may even be negative.
===========================================
USING MEMORY BARRIERS WITH CIRCULAR BUFFERS
Using memory barriers with circular buffers
===========================================
By using memory barriers in conjunction with circular buffers, you can avoid
......@@ -152,10 +148,10 @@ time, and only one thing should be emptying a buffer at any one time, but the
two sides can operate simultaneously.
THE PRODUCER
The producer
------------
The producer will look something like this:
The producer will look something like this::
spin_lock(&producer_lock);
......@@ -193,10 +189,10 @@ ordering between the read of the index indicating that the consumer has
vacated a given element and the write by the producer to that same element.
THE CONSUMER
The Consumer
------------
The consumer will look something like this:
The consumer will look something like this::
spin_lock(&consumer_lock);
......@@ -235,8 +231,7 @@ prevents the compiler from tearing the store, and enforces ordering
against previous accesses.
===============
FURTHER READING
Further reading
===============
See also Documentation/memory-barriers.txt for a description of Linux's memory
......
This diff is collapsed.
========
CPU load
--------
========
Linux exports various bits of information via `/proc/stat' and
`/proc/uptime' that userland tools, such as top(1), use to calculate
the average time system spent in a particular state, for example:
Linux exports various bits of information via ``/proc/stat`` and
``/proc/uptime`` that userland tools, such as top(1), use to calculate
the average time system spent in a particular state, for example::
$ iostat
Linux 2.6.18.3-exp (linmac) 02/20/2007
......@@ -17,7 +18,7 @@ Here the system thinks that over the default sampling period the
system spent 10.01% of the time doing work in user space, 2.92% in the
kernel, and was overall 81.63% of the time idle.
In most cases the `/proc/stat' information reflects the reality quite
In most cases the ``/proc/stat`` information reflects the reality quite
closely, however due to the nature of how/when the kernel collects
this data sometimes it can not be trusted at all.
......@@ -33,78 +34,78 @@ Example
-------
If we imagine the system with one task that periodically burns cycles
in the following manner:
in the following manner::
time line between two timer interrupts
|--------------------------------------|
^ ^
|_ something begins working |
|_ something goes to sleep
(only to be awaken quite soon)
time line between two timer interrupts
|--------------------------------------|
^ ^
|_ something begins working |
|_ something goes to sleep
(only to be awaken quite soon)
In the above situation the system will be 0% loaded according to the
`/proc/stat' (since the timer interrupt will always happen when the
``/proc/stat`` (since the timer interrupt will always happen when the
system is executing the idle handler), but in reality the load is
closer to 99%.
One can imagine many more situations where this behavior of the kernel
will lead to quite erratic information inside `/proc/stat'.
/* gcc -o hog smallhog.c */
#include <time.h>
#include <limits.h>
#include <signal.h>
#include <sys/time.h>
#define HIST 10
static volatile sig_atomic_t stop;
static void sighandler (int signr)
{
(void) signr;
stop = 1;
}
static unsigned long hog (unsigned long niters)
{
stop = 0;
while (!stop && --niters);
return niters;
}
int main (void)
{
int i;
struct itimerval it = { .it_interval = { .tv_sec = 0, .tv_usec = 1 },
.it_value = { .tv_sec = 0, .tv_usec = 1 } };
sigset_t set;
unsigned long v[HIST];
double tmp = 0.0;
unsigned long n;
signal (SIGALRM, &sighandler);
setitimer (ITIMER_REAL, &it, NULL);
hog (ULONG_MAX);
for (i = 0; i < HIST; ++i) v[i] = ULONG_MAX - hog (ULONG_MAX);
for (i = 0; i < HIST; ++i) tmp += v[i];
tmp /= HIST;
n = tmp - (tmp / 3.0);
sigemptyset (&set);
sigaddset (&set, SIGALRM);
for (;;) {
hog (n);
sigwait (&set, &i);
}
return 0;
}
will lead to quite erratic information inside ``/proc/stat``::
/* gcc -o hog smallhog.c */
#include <time.h>
#include <limits.h>
#include <signal.h>
#include <sys/time.h>
#define HIST 10
static volatile sig_atomic_t stop;
static void sighandler (int signr)
{
(void) signr;
stop = 1;
}
static unsigned long hog (unsigned long niters)
{
stop = 0;
while (!stop && --niters);
return niters;
}
int main (void)
{
int i;
struct itimerval it = { .it_interval = { .tv_sec = 0, .tv_usec = 1 },
.it_value = { .tv_sec = 0, .tv_usec = 1 } };
sigset_t set;
unsigned long v[HIST];
double tmp = 0.0;
unsigned long n;
signal (SIGALRM, &sighandler);
setitimer (ITIMER_REAL, &it, NULL);
hog (ULONG_MAX);
for (i = 0; i < HIST; ++i) v[i] = ULONG_MAX - hog (ULONG_MAX);
for (i = 0; i < HIST; ++i) tmp += v[i];
tmp /= HIST;
n = tmp - (tmp / 3.0);
sigemptyset (&set);
sigaddset (&set, SIGALRM);
for (;;) {
hog (n);
sigwait (&set, &i);
}
return 0;
}
References
----------
http://lkml.org/lkml/2007/2/12/6
Documentation/filesystems/proc.txt (1.8)
- http://lkml.org/lkml/2007/2/12/6
- Documentation/filesystems/proc.txt (1.8)
Thanks
......
===========================================
How CPU topology info is exported via sysfs
===========================================
Export CPU topology info via sysfs. Items (attributes) are similar
to /proc/cpuinfo output of some architectures:
......@@ -75,24 +78,26 @@ CONFIG_SCHED_BOOK and CONFIG_DRAWER are currently only used on s390, where
they reflect the cpu and cache hierarchy.
For an architecture to support this feature, it must define some of
these macros in include/asm-XXX/topology.h:
#define topology_physical_package_id(cpu)
#define topology_core_id(cpu)
#define topology_book_id(cpu)
#define topology_drawer_id(cpu)
#define topology_sibling_cpumask(cpu)
#define topology_core_cpumask(cpu)
#define topology_book_cpumask(cpu)
#define topology_drawer_cpumask(cpu)
The type of **_id macros is int.
The type of **_cpumask macros is (const) struct cpumask *. The latter
correspond with appropriate **_siblings sysfs attributes (except for
these macros in include/asm-XXX/topology.h::
#define topology_physical_package_id(cpu)
#define topology_core_id(cpu)
#define topology_book_id(cpu)
#define topology_drawer_id(cpu)
#define topology_sibling_cpumask(cpu)
#define topology_core_cpumask(cpu)
#define topology_book_cpumask(cpu)
#define topology_drawer_cpumask(cpu)
The type of ``**_id macros`` is int.
The type of ``**_cpumask macros`` is ``(const) struct cpumask *``. The latter
correspond with appropriate ``**_siblings`` sysfs attributes (except for
topology_sibling_cpumask() which corresponds with thread_siblings).
To be consistent on all architectures, include/linux/topology.h
provides default definitions for any of the above macros that are
not defined by include/asm-XXX/topology.h:
1) physical_package_id: -1
2) core_id: 0
3) sibling_cpumask: just the given CPU
......@@ -107,6 +112,7 @@ Additionally, CPU topology information is provided under
/sys/devices/system/cpu and includes these files. The internal
source for the output is in brackets ("[]").
=========== ==========================================================
kernel_max: the maximum CPU index allowed by the kernel configuration.
[NR_CPUS-1]
......@@ -122,6 +128,7 @@ source for the output is in brackets ("[]").
present: CPUs that have been identified as being present in the
system. [cpu_present_mask]
=========== ==========================================================
The format for the above output is compatible with cpulist_parse()
[see <linux/cpumask.h>]. Some examples follow.
......@@ -129,7 +136,7 @@ The format for the above output is compatible with cpulist_parse()
In this example, there are 64 CPUs in the system but cpus 32-63 exceed
the kernel max which is limited to 0..31 by the NR_CPUS config option
being 32. Note also that CPUs 2 and 4-31 are not online but could be
brought online as they are both present and possible.
brought online as they are both present and possible::
kernel_max: 31
offline: 2,4-31,32-63
......@@ -140,7 +147,7 @@ brought online as they are both present and possible.
In this example, the NR_CPUS config option is 128, but the kernel was
started with possible_cpus=144. There are 4 CPUs in the system and cpu2
was manually taken offline (and is the only CPU that can be brought
online.)
online.)::
kernel_max: 127
offline: 2,4-127,128-143
......
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===================================
Dell Systems Management Base Driver
===================================
Overview
========
The Dell Systems Management Base Driver provides a sysfs interface for
systems management software such as Dell OpenManage to perform system
......@@ -17,6 +22,7 @@ more information about the libsmbios project.
System Management Interrupt
===========================
On some Dell systems, systems management software must access certain
management information via a system management interrupt (SMI). The SMI data
......@@ -24,12 +30,12 @@ buffer must reside in 32-bit address space, and the physical address of the
buffer is required for the SMI. The driver maintains the memory required for
the SMI and provides a way for the application to generate the SMI.
The driver creates the following sysfs entries for systems management
software to perform these system management interrupts:
software to perform these system management interrupts::
/sys/devices/platform/dcdbas/smi_data
/sys/devices/platform/dcdbas/smi_data_buf_phys_addr
/sys/devices/platform/dcdbas/smi_data_buf_size
/sys/devices/platform/dcdbas/smi_request
/sys/devices/platform/dcdbas/smi_data
/sys/devices/platform/dcdbas/smi_data_buf_phys_addr
/sys/devices/platform/dcdbas/smi_data_buf_size
/sys/devices/platform/dcdbas/smi_request
Systems management software must perform the following steps to execute
a SMI using this driver:
......@@ -43,6 +49,7 @@ a SMI using this driver:
Host Control Action
===================
Dell OpenManage supports a host control feature that allows the administrator
to perform a power cycle or power off of the system after the OS has finished
......@@ -69,12 +76,14 @@ power off host control action using this driver:
Host Control SMI Type
=====================
The following table shows the value to write to host_control_smi_type to
perform a power cycle or power off host control action:
=================== =====================
PowerEdge System Host Control SMI Type
---------------- ---------------------
=================== =====================
300 HC_SMITYPE_TYPE1
1300 HC_SMITYPE_TYPE1
1400 HC_SMITYPE_TYPE2
......@@ -87,5 +96,4 @@ PowerEdge System Host Control SMI Type
1655MC HC_SMITYPE_TYPE2
700 HC_SMITYPE_TYPE3
750 HC_SMITYPE_TYPE3
=================== =====================
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==========================================================
ISA Plug & Play support by Jaroslav Kysela <perex@suse.cz>
==========================================================
......
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