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

David Mosberger
2002-11-07T03:13:16Z

>>>>> 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