RE: [PATCH] remove pa->va->pa conversion for efi.acpi

From: David Mosberger (
Date: Thu Jul 17 2003 - 13:09:50 EST

>>>>> On Thu, 17 Jul 2003 10:43:19 -0700, "Tolentino, Matthew E" <> said:

>> Does ACPI really guarantee that the table is never stored at physical
>> address 0? If not, then leaving it as a virtual address might be
>> safer. (Yes, I know it's very unlikely for today's system, but at
>> least on ia64, pfn 0 is normal RAM so it seems at least in principle
>> possible to store the ACPI table there).

  Matthew> No guarantee that I could find...I suppose this is
  Matthew> technically possible. :) However, considering the ACPI
  Matthew> routines expect a physical address and thus immediately map
  Matthew> it to get the descriptor (either directly with virt_to_phys
  Matthew> or via ioremap), this seems redundant. Given the mapping
  Matthew> scheme employed, is this still risky? I'd like to reuse
  Matthew> the same code path for ia32, but don't want to break ia64.

Note that I'm only pointing this out because I thought there were some
NULL-pointer checks. If it's a physical address, 0 is a valid
address. If it's an (identity-mapped) kernel address, NULL-pointer
checks are OK.

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