Re: [PATCH v3 3/4] hw/acpi: add indication for i8042 in IA-PC boot flags of the FADT table

[Bernhard Beschow]

Am 27. Februar 2022 18:58:18 UTC schrieb Liav Albani <liavalb@gmail.com>:
>
>On 2/27/22 12:48, Bernhard Beschow wrote:
>> Am 26. Februar 2022 06:30:18 UTC schrieb Liav Albani <liavalb@gmail.com>:
>>> 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.
>>>
>>> Signed-off-by: Liav Albani <liavalb@gmail.com>
>>> ---
>>> hw/acpi/aml-build.c         | 7 ++++++-
>>> hw/i386/acpi-build.c        | 8 ++++++++
>>> hw/i386/acpi-microvm.c      | 9 +++++++++
>>> include/hw/acpi/acpi-defs.h | 1 +
>>> 4 files changed, 24 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
>>> index 8966e16320..ef5f4cad87 100644
>>> --- a/hw/acpi/aml-build.c
>>> +++ b/hw/acpi/aml-build.c
>>> @@ -2152,7 +2152,12 @@ void build_fadt(GArray *tbl, BIOSLinker *linker, 
>>> const AcpiFadtData *f,
>>>      build_append_int_noprefix(tbl, 0, 1); /* DAY_ALRM */
>>>      build_append_int_noprefix(tbl, 0, 1); /* MON_ALRM */
>>>      build_append_int_noprefix(tbl, f->rtc_century, 1); /* CENTURY */
>>> -    build_append_int_noprefix(tbl, 0, 2); /* IAPC_BOOT_ARCH */
>>> +    /* IAPC_BOOT_ARCH */
>>> +    if (f->rev == 1) {
>>> +        build_append_int_noprefix(tbl, 0, 2);
>>> +    } else {
>>> +        build_append_int_noprefix(tbl, f->iapc_boot_arch, 2);
>>> +    }
>>>      build_append_int_noprefix(tbl, 0, 1); /* Reserved */
>>>      build_append_int_noprefix(tbl, f->flags, 4); /* Flags */
>>>
>>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
>>> index ebd47aa26f..65dbc1ec36 100644
>>> --- a/hw/i386/acpi-build.c
>>> +++ b/hw/i386/acpi-build.c
>>> @@ -192,6 +192,14 @@ static void init_common_fadt_data(MachineState *ms, 
>>> Object *o,
>>>              .address = object_property_get_uint(o, ACPI_PM_PROP_GPE0_BLK, 
>>> NULL)
>>>          },
>>>      };
>>> +    /*
>>> +     * second bit of 16 but IAPC_BOOT_ARCH indicates presence of 8042 or
>>> +     * equivalent micro controller. See table 5-10 of APCI spec version 2.0
>>> +     * (the earliest acpi revision that supports this).
>>> +     */
>>> +
>>> +    fadt.iapc_boot_arch = isa_check_device_existence("i8042") ? 0x0002 : 
>>> 0x0000;
>> Couldn't qdev_find_recursive() be used here instead? This would also make 
>> patch 1 unneccessary. Same below.
>>
>> Best regards
>> Bernhard
>
>I tried it first, but because it tries to find the ID of a device 
>instead of a type (I look for i8042 type which is a string of the device 
>type), it didn't work as expected. We don't compare DeviceState id, but 
>ObjectClass type->name here :)

I see. What about object_resolve_path_type()? It takes a typename parameter. It 
even tells you if the match is ambiguous if you care.

Best regards,
Bernhard

>
>With my patch we could just find the device without any problem whatsoever.
>
>Best regards,
>Liav
>