Hi,
On 4/12/21 8:11 PM, Rafael J. Wysocki wrote:
> On Mon, Apr 12, 2021 at 8:01 PM Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
>>
>> On Mon, Apr 12, 2021 at 7:38 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>>>
>>> Hi Rafael,
>>>
>>> Sorry about the timing of reporting this regression.
>>
>> Oh well.
>>
>>> I just noticed that overriding the DSDT (*) from the initrd will not work in 5.12,
>>> this is caused by:
>>>
>>> commit 1a1c130ab757 ("ACPI: tables: x86: Reserve memory occupied by ACPI tables")
>>>
>>> This makes the initial acpi_locate_initial_tables() call happen earlier
>>> then before, but the acpi_table_upgrade) call in arch/x86/kernel/setup.c is
>>> not moved up, so the tables in the initrd are now only parsed and saved
>>> after the initial ACPI table scanning has already been done.
>>>
>>> I guess fixing this might be as easy as moving the acpi_table_upgrade) call
>>> higher in arch/x86/kernel/setup.c but I'm not sure if that is save to do.
>>
>> Why do you think it may not be safe?
>
> OK, so it won't work in some cases, because acpi_table_upgrade() needs
> to be called after reserve_initrd(),
Right I notice it was sitting right after reserve_initrd() which made me think
that it probably needed to be after that. Sorry I should have mentioned that
in my original email.
> so I guess the commit above will
> need to be reverted.
One possible solution which I was wondering about is to modify
acpi_table_initrd_scan() to have it call acpi_tb_override_table()
instead of acpi_install_table() for existing tables using the matching
logic from acpi_table_initrd_override(). But I'm not sure when the
parsing of the DSDT is done. If acpi_table_initrd_scan() runs before
the first parsing of the DSDT is done then I think that that should work.
This might be more 5.13 material though and for 5.12 a revert is
probably best.
I also just remembered that at least the Intel audio folks rely on
DSDT overrides to get some (prototype) boards in their CI to work.
Regards,
Hans
