Re: [Qemu-devel] [PATCH] i386/acpi: add _HID to processor nodes

[Michael S. Tsirkin]

On Thu, Oct 22, 2015 at 12:38:11PM +0200, Matthias Lange wrote:
> Processor nodes created via the acpi/aml framework currently don't
> feature a _HID string. This patch appends "ACPI0007" as the _HID
> string to each processor node.
> 
> Signed-off-by: Matthias Lange <address@hidden>

Indeed,  it does that.  But why?

ACPI0007 Processor Device. This device provides an alternative to
declaring processors using the
Processor ASL statement.


And “Declaring Processors” says


        Each processor in the system must be declared in the ACPI namespace in
        either the \_SB or \_PR
        scope but not both. Declaration of processors in the \_PR scope is
        required for platforms desiring
        compatibility with ACPI 1.0-based OSPM implementations. Processors are
        declared either via the
        ASL Processor statement or the ASL Device statement. A Processor
        definition declares a processor
        object that provides processor configuration information and points to
        the processor register block
        (P_BLK). A Device definition for a processor is declared using the
        ACPI0007 hardware identifier
        (HID). In this case, processor configuration information is provided
        exclusively by objects in the
        processor device’s object list.

In other words, Processor directive does not need a HID.
In fact, ACPI 1.0 didn't include the ACPI0007 HID at all.


Please include this info in both the commit log and a code comment.


> ---
>  hw/i386/acpi-build.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 95e0c65..95f7bf9 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1153,6 +1153,7 @@ build_ssdt(GArray *table_data, GArray *linker,
>          for (i = 0; i < acpi_cpus; i++) {
>              dev = aml_processor(i, 0, 0, "CP%.02X", i);
>  
> +            aml_append(dev, aml_name_decl("_HID", aml_string("ACPI0007")));
>              method = aml_method("_MAT", 0);
>              aml_append(method, aml_return(aml_call1("CPMA", aml_int(i))));
>              aml_append(dev, method);
> -- 
> 1.9.1