Re: Next round of console patches
Richard Gooch (rgooch@atnf.csiro.au)
Sun, 30 Aug 1998 20:45:29 +1000
Tom Eastep writes:
> Richard Gooch wrote:
> > OK, that would make sense if the write-combining is fouling up MMIO
> > register access. Can you please patch your kernel where it calls
> > mtrr_add() and add another call to mtrr_add() so that you set up a
> > small uncacheable region either at the beginning or the end of the
> > framebuffer?
> > With luck that will fix it. If it does, start trimming the uncacheable
> > region down in size until it fails again. That will tell you the
> > minimum size of the register region. If you're unsure of how big a
> > region to start with (say 4 kBytes still fails), make the entire
> > framebuffer uncacheable and step down in factors of two.
>
> Ok -- I patched vesafb.c as follows:
>
> mtrr_add((unsigned long)video_base, video_size, MTRR_TYPE_WRCOMB, 1);
> + mtrr_add((unsigned long)video_base, video_size, MTRR_TYPE_UNCACHABLE,
> 1);
>
> I still got the lockup.
That's quite bad. Can you do two separate tests, please? Firstly,
insert a printk just before the call to mtrr_add() and send me a copy
of your kernel logs?
Secondly, disable that code from the kernel and instead use the
/proc/mtrr interface and tell me if the problem goes away or not.
Finally, do you have an SMP machine?
Regards,
Richard....
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