Re: ESRT failures ... was Re: [PATCH 04/11] efi: Add efi_memmap_init_late() for permanent EFI memmap

[Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>]

On Thu, 21 Jul, at 10:44:32AM, Prarit Bhargava wrote:
> 
> 
> On 07/21/2016 08:11 AM, Matt Fleming wrote:
> > 
> > efi_mem_desc_lookup() should just return the correct EFI memory
> > descriptor now that we have efi_mem_reserve() coming in v4.9.
> > 
> > What does the EFI memmap (as printed with efi=debug) look like on your
> > machine?
> > 
> 
> [    0.000000] efi: EFI v2.40 by Dell Inc.
> [    0.000000] efi:  ESRT=0x8eb1c000  ACPI=0x8efe7000  ACPI 2.0=0x8efe7014
> SMBIOS=0x8ef69000
> 
> and
> 
> [    0.000000] efi: mem249: [Reserved           |   |  |  |  |  |  |  |
> |WB|WT|WC|UC] range=[0x000000008d6df000-0x000000008ef69fff] (24MB)

Yeah, that's a Dell firmware bug. This should be EFI boot services
data. Quoting the spec Section 22.3 EFI System Resource Table,

  "See Section 4.6 for description of how to publish ESRT using
   EFI_CONFIGURATION_TABLE. The ESRT shall be stored in memory of type
   EfiBootServicesData."

We do not use regions mark EFI_RESERVED_TYPE because they're basically
supposed to be unusable by the OS, AFAIK. I guess we'll have to update
efi_mem_desc_lookup() to return reserved regions and make sure they're
always contained within the memmap.