Who is stomping PCI config space?

[Jon Smirl]

My understanding of the X source code is limited, can anyone tell me
where X is turning off secondary cards on VT switch?

The patch looks like it keeps X from getting secondary cards onto the
list of cards to begin with.

Can anyone explain why X is disabling cards on VT switch that it does
not have drivers loaded for? This behavior just toasts my fbdev
driver. My driver is getting interrupts, now I switch VTs to X and the
card's MMIO window disappears. Of course my driver messes up, it go
into a hard loop servicing an interrupt it can't acknowledge.


On Fri, 04 Mar 2005 10:07:25 +1100, Benjamin Herrenschmidt
<benh at kernel.crashing.org> wrote:
> On Thu, 2005-03-03 at 14:03 -0500, Jon Smirl wrote:
> > I have two video cards:
> > PCI Rage128
> > AGP Radeon
> >
> > X is loaded on the Rage128 on VT7
> > X is not configured to support the radeon
> >
> > I switch to VT1 and load radeonfb
> > This works fine.
> >
> > Now I switch to VT7 and dump PCI config space for the radeon
> >
> > [root at jonsmirl 0000:01:00.0]# hexdump config >/foo
> > [root at jonsmirl 0000:01:00.0]# diff /foo /bar
> > 1c1
> > < 0000000 1002 4966 0080 02b0 0001 0300 4010 0080
> > ---
> > > 0000000 1002 4966 0083 02b0 0001 0300 4010 0080
> > 4c4
> > < 0000030 0000 fea0 0058 0000 0000 0000 010b 0008
> > ---
> > > 0000030 0000 fe90 0058 0000 0000 0000 010b 0008
> > [root at jonsmirl 0000:01:00.0]#
> >
> > Somebody is changing PCI command from 83 to 80 and disabling my
> > radeon's memory and iospace. Who is doing this? It has to be X since
> > it doesn't happen if I switch to VT6 or VT8.
> >
> > Why is X mucking with a card it doesn't have a driver loaded for?
> > Where is this happening in the X code?
> 
> I had a report of something similar with X and a mach64 ... I haven't
> yet investigated, but basically, X is using "fbdev" (so no specific
> driver) and seem to be disabling memory access to the card, thus blowing
> up the kernel fbdev.
> 
> Ben.
> 
> 


-- 
Jon Smirl
jonsmirl at gmail.com