Re: [Xen-devel] [PATCH] x86/efi: Do not write relocations in efi_arch_relocate_image() first pass

["Jan Beulich" <jbeulich@xxxxxxxx>]

>>> David Woodhouse <dwmw2@xxxxxxxxxxxxx> 08/02/17 4:45 PM >>>
>On Wed, 2017-08-02 at 07:58 -0600, Jan Beulich wrote:
>> > > > David Woodhouse <dwmw2@xxxxxxxxxxxxx> 08/02/17 2:11 PM >>>
>> > This change is sufficient (we believe) to make EFI builds of Xen
>> > actually boot again on current EDK2, is it not?
>>
>> It is safe / sufficient only with the specific behavior you've observed, i.e.
>> when permission restrictions are being removed during ExitBootServices().
>> I don't recall having seen any statement to that effect in the spec, and
>> even if there was such a statement surely we'd find a firmware vendor
>> who doesn't play by it.
>
>I'd be relatively surprised if a vendor were to make changes to the
>underlying TianoCore/EDK2 implementation in this respect. It doesn't
>seem like one of the areas in which they would want to apply the "value
>subtract" that they so desperately cling to.

Well, I've seen breakage in all sorts of places I wouldn't have expected
anyone to fine a need to fiddle with.

>Perhaps we should push to have the spec amended to mandate the current
>behaviour?

That would be nice, but wouldn't keep people from still getting it wrong,
I'm afraid.

>(Hm, ick... the more I look at this, the more I wish my initial
>response had been "la la la it was already broken it wasn't me..." :)

;-)

Jan


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