Re: [PATCH v2 3/8] MdeModulePkg/DxeCorePerformanceLib:Track FPDT record in DXE phase

[Laszlo Ersek <lersek@redhat.com>]

Hi Star,

On 05/22/18 11:38, Zeng, Star wrote:
> It comes to an old question: how to know PEI is 32bit/64bit? But not DXE is 32bit/64bit.

we've discussed this question in the past (as you remember :) ) and
people suggested both HOBs and PCDs to expose the "PEI phase max
address" to DXE. All of those ideas were rejected -- I'm unsure why, to
this day --, but assuming people who opposed those ideas are going to
oppose them again, I think Ard's idea is good, about introducing
dedicated MemoryAllocationLib interfaces, for PEI-targeted memory
allocation.

Once drivers adopt these new interfaces, platforms can at least fork the
MemoryAllocationLib instance(s) they need, and customize the PEI phase
max address one way or another.

Thanks,
Laszlo

> -----Original Message-----
> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org] 
> Sent: Tuesday, May 22, 2018 5:03 PM
> To: Zeng, Star <star.zeng@intel.com>
> Cc: Bi, Dandan <dandan.bi@intel.com>; Laszlo Ersek <lersek@redhat.com>; Andrew Fish <afish@apple.com>; Kinney, Michael D <michael.d.kinney@intel.com>; Leif Lindholm <leif.lindholm@linaro.org>; edk2-devel@lists.01.org; Gao, Liming <liming.gao@intel.com>; Matt Sealey <neko@bakuhatsu.net>
> Subject: Re: [edk2] [PATCH v2 3/8] MdeModulePkg/DxeCorePerformanceLib:Track FPDT record in DXE phase
> 
> pd On 22 May 2018 at 10:58, Zeng, Star <star.zeng@intel.com> wrote:
>> How about the code to try allocating <4G memory, then try allocating any memory if failed to allocate <4G memory?
>>
>> For example, the code snippet in SmbiosDxe.c.
>>
>>     PhysicalAddress = 0xffffffff;
>>     Status = gBS->AllocatePages (
>>                     AllocateMaxAddress,
>>                     EfiRuntimeServicesData,
>>                     EFI_SIZE_TO_PAGES (sizeof (SMBIOS_TABLE_ENTRY_POINT)),
>>                     &PhysicalAddress
>>                     );
>>     if (EFI_ERROR (Status)) {
>>       DEBUG ((EFI_D_ERROR, "SmbiosCreateTable () could not allocate EntryPointStructure < 4GB\n"));
>>       Status = gBS->AllocatePages (
>>                       AllocateAnyPages,
>>                       EfiRuntimeServicesData,
>>                       EFI_SIZE_TO_PAGES (sizeof (SMBIOS_TABLE_ENTRY_POINT)),
>>                       &PhysicalAddress
>>                       );
>>      if (EFI_ERROR (Status)) {
>>         return EFI_OUT_OF_RESOURCES;
>>       }
>>     }
>>
> 
> Yes, that should do the trick.
> 
> But perhaps we should add something like
> 
> AllocatePeiAccessiblePages()
> 
> to MemoryAllocationLib, which just uses AllocateMaxAddress or
> AllocateAnyPages depending on whether MDE_CPU_X64 is #defined.
>