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

From: David Mosberger <davidm_at_napali.hpl.hp.com>
Date: 2002-11-07 14:13:16
>>>>> 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
Received on Wed Nov 06 19:14:56 2002

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