Re: [PATCH v3 3/5] x86: Call efi_memblock_x86_reserve_range() on native EFI platform only

From: Jan Beulich
Date: Wed Mar 26 2014 - 09:39:55 EST


>>> On 26.03.14 at 14:31, <matt@xxxxxxxxxxxxxxxxx> wrote:
> On Wed, 26 Mar, at 01:22:49PM, Jan Beulich wrote:
>> >>> On 26.03.14 at 14:00, <matt@xxxxxxxxxxxxxxxxx> wrote:
>> >
>> > This could do with a little bit more explanation. Why is it not
>> > necessary to mark the EFI memory map that was passed to the kernel as
>> > reserved in memblock?
>>
>> Because that's in memory Dom0 doesn't even see: The EFI memory
>> map is visible to the hypervisor only.
>
> So where does boot_params.efi_info.efi_memmap point?
>
> If nowhere (i.e. it's NULL) that's no problem because memblock_reserve()
> handles zero size regions just fine.

That's a question to Daniel - in our implementation (with a separate
Xen kernel that can't run on bare hardware) boot_params as a whole
simply doesn't exist.

Jan

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