David,
        Thanks for the information.
        For HiPermanentMemoryAddress and HiPermanentMemorySize, I want to 
confirm that they are for the permanent memory allocation defined in PCI 
Firmware 3.0 spec:

5.2.1.7. Permanent Memory
Permanent memory will continue to be assigned to the Expansion ROM even after 
the operating
system has booted. This is accomplished by the BIOS updating the data for the 
Interrupt 15h,
E820h function (“Get Memory Map”), to show that this memory allocated to the 
Expansion ROM
is reserved, private, and unmovable.
In addition, the BIOS must support the ACPI memory tables that describe 
reserved regions of
memory. Interrupt 15h, E820h function (“Get Memory Map”), and the ACPI memory 
tables must
both contain entries for the memory reserved by Expansion ROMs.

        So EFI reserved memory above 1MB will be allocated in LegacyBiosDxe, 
and assign this reserved memory to 
HiPermanentMemoryAddress/HiPermanentMemorySize for new CSM16?

Thanks
Elvin

-----Original Message-----
From: David Woodhouse [mailto:dw...@infradead.org] 
Sent: Tuesday, May 13, 2014 10:13 PM
To: Li, Elvin
Cc: edk2-devel@lists.sourceforge.net
Subject: Re: [edk2] [PATCH] LegacyBios: Update EFI_COMPATIBILITY16_TABLE to 
match 0.98 CSM spec update

On Tue, 2014-05-13 at 13:13 +0100, David Woodhouse wrote:
> 
> Hi Elvin,
> 
> These fields are defined in the v0.98 update to the CSM specification,
> available at
> http://www.intel.com/content/www/us/en/architecture-and-technology/unified-extensible-firmware-interface/efi-compatibility-support-module-specification-v098.html
> 
> The UmaAddress and UmaSize fields allow a CSM to use memory between
> 0xc0000 and 0xfffff as RAM, instead of having it marked read-only by the
> LegacyRegion implementation on the UEFI side. Some implementations, such
> as SeaBIOS, want to put stacks there to avoid overflowing a low-memory
> application/OS stack.

FWIW you can see the SeaBIOS side of this same API addition at
http://git.infradead.org/users/dwmw2/seabios.git/commitdiff/e763ac340

-- 
David Woodhouse                            Open Source Technology Centre
david.woodho...@intel.com                              Intel Corporation
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