Re: Intel BIOS - Corrupted low memory at ffff880000004200

[Alexey Fisher]

Thomas Gleixner schrieb:
> On Fri, 10 Jul 2009, Alexey Fisher wrote:
> > Ingo Molnar schrieb:
> > > * Matthew Garrett <mjg59@xxxxxxxxxxxxx> wrote:
> > >
> > > > On Mon, Jul 06, 2009 at 06:24:47PM +0200, Alexey Fisher wrote:
> > > > > Hallo Ingo, Richard.
> > > > >
> > > > > I'm getting "Corrupted low memory" trace with my Intel DG45ID board
> > > > > after resume. This board has different dmi-bios-vendor... so probably it
> > > > > will be nice to have it in your patch.
> > > > I'm beginning to think that we should be doing this on all hardware,
> > > > perhaps with a kernel option to disable it for embedded devices that
> > > > really need that 64K. The low-memory corruption issue seems to be very
> > > > widespread.
> > > The problem is that the BIOS corrupted memory that it also marked as
> > > 'usable' in its E820 map it gave to the kernel. If that memory is not
> > > usable, it should not have been marked as such. Also, some of the reports
> > > showed corruption beyond this range so the workaround is not universal.
> > >
> > > So i'd really like to know what is happening there, instead of just zapping
> > > support for 64K of RAM on the majority of Linux systems.
> > >
> > > We might end up doing the same thing in the end (i.e. disable that 64k of
> > > RAM) - but it should be an informed decision, not a wild stab in the dark.
> > >
> > > 	Ingo
> > If i make memory dump like "dd if=/dev/mem of=memdump.dd bs=64k count=1"
> > before and after suspend. Will it help you find out whats happening.
>
> The corrupted low memory printks contain the modifications. Can you
> post them please ?
>
> Thanks,
>
> 	tglx

I dumped all between 0000000 - 00ffff0
and there is changes at:
0004200 ->  this know one
003c000 - 003fff0 -> this was empty and now it looks like VBIOS
00d18a0 -> i don't know

cat /proc/iomem
00000000-0000ffff : reserved
00010000-0009e7ff : System RAM
0009e800-0009ffff : reserved
000e0000-000fffff : reserved
00100000-bd90dfff : System RAM
  01000000-014b1f1b : Kernel code
  014b1f1c-0171265f : Kernel data
  01794000-01842c07 : Kernel bss
.....
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/