[PATCH] xfree86: Use SA_SIGINFO if available for SIGIO handlers

[Mark Kettenis]

> From: Adam Jackson <ajax at redhat.com>
> Date: Tue, 10 Nov 2009 15:03:31 -0500
> 
> This one's slightly subtle, the fcntl(F_SETSIG) is required for ->si_fd
> to actually be filled in correctly, at least on Linux.  I know this area
> has been sensitive to platform variation in the past, so I'd appreciate
> a second look from Solaris / BSD / Hurd people.

Alas, OpenBSD doesn't have si_fd.  So if you really want to go this
route, you'll need to add an additional configure check for it.

> siginfo_t gives us the file descriptor that raised the signal directly,
> so we don't need to select() for it.  This gets evdev event processing
> down to exactly one syscall in the common case.

Is that an optimizition that's really worth the added complexity?