Commit f9c235e6 authored by Pavel Machek's avatar Pavel Machek Committed by Linus Torvalds

[PATCH] swsusp: documentation update

Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 85bbce68
...@@ -202,3 +202,30 @@ or an NFS share[Work In Progress]). Questions regarding suspend2 ...@@ -202,3 +202,30 @@ or an NFS share[Work In Progress]). Questions regarding suspend2
should be sent to the mailing list available through the suspend2 should be sent to the mailing list available through the suspend2
website, and not to the Linux Kernel Mailing List. We are working website, and not to the Linux Kernel Mailing List. We are working
toward merging suspend2 into the mainline kernel. toward merging suspend2 into the mainline kernel.
Q: Kernel thread must voluntarily freeze itself (call 'refrigerator'). But
I found some kernel threads don't do it, and they don't freeze, and
so the system can't sleep. Is this a known behavior?
A: All such kernel threads need to be fixed, one by one. Select place
where it is safe to be frozen (no kernel semaphores should be held at
that point and it must be safe to sleep there), and add:
if (current->flags & PF_FREEZE)
refrigerator(PF_FREEZE);
Q: What is the difference between between "platform", "shutdown" and
"firmware" in /sys/power/disk?
A:
shutdown: save state in linux, then tell bios to powerdown
platform: save state in linux, then tell bios to powerdown and blink
"suspended led"
firmware: tell bios to save state itself [needs BIOS-specific suspend
partition, and has very little to do with swsusp]
"platform" is actually right thing to do, but "shutdown" is most
reliable.
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