RE: [Linux-ia64] [PATCH]ACPI fACS global lock & virtual memmap

Sluder, Charles
2002-11-07T18:02:38Z

I submitted a problem report on the firmware. Will have to wait and see if
they will make changes.

Thanks for solving our problems. The effort is very much appreciated.

-chuck

-----Original Message-----
From: David Mosberger [mailto:davidm@napali.hpl.hp.com]
Sent: Wednesday, November 06, 2002 8:13 PM
To: Sluder, Charles
Cc: linux-ia64@linuxia64.org
Subject: RE: [Linux-ia64] [PATCH]ACPI fACS global lock & virtual memmap

>>>>> On Wed, 6 Nov 2002 20:52:40 -0600 , "Sluder, Charles"
<Charles.Sluder@UNISYS.com> said:

Chuck> I tried the patch and it gets rid of the panic. Before and
Chuck> after dumps of the memory map are below. The SAL and ACPI
Chuck> tables are being trimmed from the memory map. That is why the
Chuck> FACS global lock is mapped uncached. Debug from
Chuck> acpi_map_os_memory is also include below.

Chuck> Shouldn't the trim code ignore runtime memory?

No, it can't ignore it. There is a real problem here: the ACPI table
lies in a 64MB granule which has a hole (because of the missing 4KB
page at 0x000000007ffff000). Because of that, the kernel simply
cannot safely access that memory via a write-back mapping (the reason
is that the processor prefetch or a speculative load might otherwise
access the hole and MCA while doing that).

So as it stands, Linux simply won't be able to work correctly on a
machine with this kind of memory map. Can you move the firmware
tables to a granule which is fully populated?

--david

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