Re: 2.6.17-rc1-mm1

[Zou Nan hai <nanhai.zou@intel.com>]

On Wed, 2006-04-05 at 07:38, Luck, Tony wrote:
> On Tue, Apr 04, 2006 at 01:45:04AM -0700, Andrew Morton wrote:
> > - VGA on ia64 is broken - the screen comes up blank.  But ia64 otherwise
> >   seems to work OK.  I didn't have time to investigate.
> 
> Broken in base 2.6.17-rc1 too :-(  VGA comes up and prints a
> few messages, and then goes wonky and dies.  Comparing
> what I _think_ I saw with the dmesg output, it appears to
> die here:
> 

The wild VGA comes from the patch which changed ioremap.

Now ioremap would not remap memory to region 6 unless that memory is
marked as EFI_MEMORY_UC by EFI.

Unfortunately on the Tiger Machine, VGA ram base was marked as
EFI_MEMORY_WB instead of EFI_MEMORY_UC...

So you can see the problem disappear if change VGA_MAP_MEM to use
ioremap_nocache.

But I am not quite sure if we can fully trust EFI on this attribute.

Zou Nan hai