On Tue, 19 Jan 2016, Shannon Zhao wrote:

On 2016/1/19 21:13, Mark Rutland wrote:

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On Tue, Jan 19, 2016 at 12:23:17PM +0000, Stefano Stabellini wrote:

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On Tue, 19 Jan 2016, Mark Rutland wrote:

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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

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should do so here.

Does Xen handle arbitrary size memory map descriptors? I'm

not sure what

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new information might be passed in future additions to the

descriptor

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format, and I'm not sure what should happen in the Dom0

case.

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

native

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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

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Does it pass the raw values returned by

EFI_BOOT_SERVICES.GetMemoryMap()

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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 take it that means that any memory carved out for Xen itself is
described/discovered via a separate mechanism? How does that work

For Xen hypervisor booting on UEFI, it get the EFI memory map through the
similar way like Linux, e.g. call EFI_BOOT_SERVICES.GetMemoryMap().
For Dom0, Xen will create a new EFI memory map for Dom0.

See [PATCH v3 52/62] arm/acpi: Prepare EFI memory descriptor for Dom0
http://lists.xen.org/archives/html/xen-devel/2015-11/msg01884.html

Ah! That patch is not upstream yet, that's why I thought that something
was off. Listen to Shannon, don't listen to me :-)