Re: [Qemu-devel] [PATCH RFC] acpi: add reset register to fadt

[Laszlo Ersek <lersek@redhat.com>]

On 02/06/17 17:44, Phil Dennis-Jordan wrote:
> On 31 January 2017 at 20:08, Laszlo Ersek <lersek@redhat.com> wrote:
>> On 01/31/17 19:17, Michael S. Tsirkin wrote:
>>> On Tue, Jan 31, 2017 at 05:28:57PM +0100, Laszlo Ersek wrote:
>>>> The ACPI 6.1 spec says,
>>>>
>>>> - DSDT: [...] If the X_DSDT field contains a non-zero value then this
>>>>   field must be zero.
>>>> - X_DSDT: [...] If the DSDT field contains a non-zero value then this
>>>>   field must be zero.
>>>
>>> But that's only 6.1. 6.0 and earlier did not say this.
>>> The errata they wanted to address was:
>>> 1393 In FADT: if X_DSDT field is non-zero, DSDT
>>> field should be ignored or deprecated
>>>
>>> I would class this as a spec bug.
>>>
>>
>> Process-wise, that's not a bad idea; it could be the only way (or the
>> best way) to argue for a corresponding change in edk2's
>> EFI_ACPI_TABLE_PROTOCOL implementation
>> (MdeModulePkg/Universal/Acpi/AcpiTableDxe).
>>
>> Do you want to raise this on the ASWG list? I vaguely recall that you
>> subscribed; if not, I think you should be able to, as a Red Hatter
>> <http://members.uefi.org/kmembership_info/person_signup/>.
>>
>> (I'd like to avoid being the middle man.)
>>
>> Hm... It seems that the "Adopter Membership" is free, which could be
>> appropriate for individual observers:
>>
>> http://uefi.org/join
>> http://members.uefi.org/home/
>>
>> (Should Phil consider it.)
> 
> To be honest, I have no idea - does the revelation of 5.1b's
> introduction of the mutual exclusivity, and the fact that you've
> written up an edk2 patch change anything? If my signing up for
> membership will help with resolving the problem, I'm happy to do it,
> I'm just lacking the context to know if this is the case - please let
> me know.

I'm neither encouraging you to, nor discouraging you from, joining the
ASWG :) I just wanted to share the details that I managed to find,
should you want to join the ASWG in order to (co-)champion the question
(with Michael).

For example, elsewhere you mention that Windows 10 "insist[s] on both
DSDT and X_DSDT" [1]. That is somewhat in conflict with the most recent
spec requirements that both fields be exclusive... If you've seen this
happen first hand, that can be a strong argument to make.

[1] https://lists.01.org/pipermail/edk2-devel/2017-February/007072.html

Thanks,
Laszlo