Re: multi-domain PCI and sysfs

David S. Miller
2004-09-08T04:19:41Z

On Tue, 7 Sep 2004 21:15:09 -0700
Jesse Barnes <jbarnes@engr.sgi.com> wrote:

> On Tuesday, September 7, 2004 4:11 pm, David S. Miller wrote:
> > This is a real touchy area btw, because if there is no
> > VGA card, such I/O port accesses are going to trap and
> > we need to have a common way to handle that somehow.
>
> So I take it your platform won't soft fail the accesses and return all 1s?

Nope, you get a machine check trap. We have to catch these when doing
PCI config space accesses in the kernel too. Grep for pci_poke_* in
arch/sparc64/kernel/*.c

> A potentially cleaner option which Ben and I would prefer is to use
> the vga device Jon is creating to do legacy I/O with explicit
> read/write or ioctl calls.

Definitely. Note that xfree86 already has a signal handler for this
stuff, ppc generates traps like sparc64 too.