On Tue, 19 Jan 2016, Mark Rutland wrote:

On Tue, Jan 19, 2016 at 06:25:25PM +0800, Shannon Zhao wrote:

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We don't do this in Documentation/arm/uefi.txt, and I don't see why we
should do so here.

Does Xen handle arbitrary size memory map descriptors? I'm not sure what
new information might be passed in future additions to the descriptor
format, and I'm not sure what should happen in the Dom0 case.

Xen passes to Dom0 the memory map in the same format as the native
memory map.

Does Xen parse or modify the EFI memory map in any way?

Xen:
- calls EFI_BOOT_SERVICES.GetMemoryMap()
- takes note of the memory regions for its own usage
- create the fdt notes, including efi-mmap-start, with a pointer to it

Does it pass the raw values returned by EFI_BOOT_SERVICES.GetMemoryMap()
through to the xen,uefi-* properties, or does is make any static
assumptions about what the values will be?

It just passes the raw values.

I'm trying to get a feeling for what the behaviour will be if/when a
version of the EFI spec expands the memory map format.

Linux is likely to get the memory map in the same format as it's
provided on native.