• Chris Metcalf's avatar
    arch/tile: Add driver to enable access to the user dynamic network. · 9f9c0382
    Chris Metcalf authored
    This network (the "UDN") connects all the cpus on the chip in a
    wormhole-routed dynamic network.  Subrectangles of the chip can
    be allocated by a "create" ioctl on /dev/hardwall, and then to access the
    UDN in that rectangle, tasks must perform an "activate" ioctl on that
    same file object after affinitizing themselves to a single cpu in
    the region.  Sending a wormhole-routed message that tries to leave
    that subrectangle causes all activated tasks to receive a SIGILL
    (just as they would if they tried to access the UDN without first
    activating themselves to a hardwall rectangle).
    
    The original submission of this code to LKML had the driver
    instantiated under /proc/tile/hardwall.  Now we just use a character
    device for this, conventionally /dev/hardwall.  Some futures planning
    for the TILE-Gx chip suggests that we may want to have other types of
    devices that share the general model of "bind a task to a cpu, then
    'activate' a file descriptor on a pseudo-device that gives access to
    some hardware resource".  As such, we are using a device rather
    than, for example, a syscall, to set up and activate this code.
    
    As part of this change, the compat_ptr() declaration was fixed and used
    to pass the compat_ioctl argument to the normal ioctl.  So far we limit
    compat code to 2GB, so the difference between zero-extend and sign-extend
    (the latter being correct, eventually) had been overlooked.
    Signed-off-by: default avatarChris Metcalf <cmetcalf@tilera.com>
    Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
    9f9c0382
hardwall.h 1.64 KB