On Friday, December 3, 2004 8:31 am, Jesse Barnes wrote:
> [This is a repost of an earlier patch now that I've had time to finish it
> and test it more thoroughly.]
>
> This patch adds support for sending a SIGBUS to a userspace application
> using /proc/bus/pci to drive a device if an I/O error occurs.  We're using
> this in house for the X server's BIOS emulator and it seems to be working
> well.
>
> The idea is to track mmaped /proc/bus/pci regions so that the machine check
> handler is able to properly determine which process is responsible for any
> faults that occur (ia64 is interesting in that the error may not occur in
> the process context that actually generated the bad reference).  If a match
> is found, a SIGBUS is sent to the process, along with the address that
> caused the fault.  The machine check record is then cleared and recovery
> takes place (the assumption is that the signal to userspace is a sufficient
> record of the error).
>
> The patch also special cases memory mapping of legacy space, which is the
> first 64k of I/O space and the first megabyte of memory space.  Sub
> platforms can optionally remap their bridge to the target bus and setup
> legacy handling in the callout.
>
> Comments?  Given that this is working well for us, I'd like to get it
> upstream sometime soon.  I also expect that it could be used to deal with
> more types of I/O errors, perhaps allowing the kernel to call a driver
> shutdown routine if an I/O error occurs in a kernel driver.

Doh!  This is the updated one I meant to send.

Jesse