Re: [PATCH v4 2/3] hw/acpi: add indication for i8042 in IA-PC boot flags of the FADT table

[Ani Sinha]

On Wed, Mar 2, 2022 at 12:41 AM Liav Albani <liavalb@gmail.com> wrote:
>
>
> On 3/1/22 13:19, Michael S. Tsirkin wrote:
> > On Tue, Mar 01, 2022 at 09:43:54AM +0100, Igor Mammedov wrote:
> >> On Mon, 28 Feb 2022 22:17:32 +0200
> >> Liav Albani <liavalb@gmail.com> wrote:
> >>
> >>> This can allow the guest OS to determine more easily if i8042 controller
> >>> is present in the system or not, so it doesn't need to do probing of the
> >>> controller, but just initialize it immediately, before enumerating the
> >>> ACPI AML namespace.
> >>>
> >>> This change only applies to the x86/q35 machine type, as it uses FACP
> >>> ACPI table with revision higher than 1, which should implement at least
> >>> ACPI 2.0 features within the table, hence it can also set the IA-PC boot
> >>> flags register according to the ACPI 2.0 specification.
> >>>
> >>> Signed-off-by: Liav Albani <liavalb@gmail.com>
> >>> ---
> >>>   hw/acpi/aml-build.c         | 11 ++++++++++-
> >>>   hw/i386/acpi-build.c        |  9 +++++++++
> >>>   hw/i386/acpi-microvm.c      |  9 +++++++++
> >> commit message says it's q35 specific, so wy it touched microvm anc piix4?
> >>
> This affect only q35 machine type for now, but what happens if the
> MicroVM ACPI FACP table is updated to use a revision that supports IA-PC
> boot flags?

microvm FACP table uses version 5. See function acpi_build_microvm().
It supports that flag already. What Igor was trying to say (and he can
correct me if I am wrong) is that lets address microvm when the need
arises, unless we already envision today that we would need IA-PC boot
flag update even for microvms in the near future. In other words, lets
not touch microvms if we do not have to, at present.