Re: [Xen-devel] [PATCH] efi/libstub/fdt: Standardize the names of EFI stub parameters

[Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>]

(snip some cc's)

On 14 September 2015 at 11:31, Shannon Zhao <zhaoshenglong@xxxxxxxxxx> wrote:
>
>
> On 2015/9/14 17:09, Ard Biesheuvel wrote:
>> On 14 September 2015 at 10:42, Shannon Zhao <zhaoshenglong@xxxxxxxxxx> wrote:
>> [..]
>>
>>>
>>> It only needs to apply following patch to fix a bug in Linux kernel when
>>> mapping EFI_MEMORY_RUNTIME memory.
>>>
>>
>> Could you explain why you think efi_virtmap_init() should fail if
>> there are no EFI_MEMORY_RUNTIME regions?
>>
>
> My understanding is that if there are no EFI_MEMORY_RUNTIME regions, it
> means we can't use runtime services and should not set the bit
> EFI_RUNTIME_SERVICES of efi.flags. But if efi_virtmap_init() return
> true, the bit will be set.
>

As I said, if you don't want the EFI_RUNTIME_SERVICES bit to be set
for other reasons, don't rig efi_virtmap_init() to return false when
it shouldn't.

>> The absence of such regions is allowed by the spec, so
>> efi_virtmap_init() is correct imo to return success.
>>
> Sorry, not well know about the spec. Could you point out where the spec
> says this?
>

Well, I think it doesn't work that way. You are claiming that a memory
map without at least one EFI_MEMORY_RUNTIME constitutes an error
condition, so the burden is on you to provide a reference to the spec
that says you must have at least one such region.

-- 
Ard.

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