Re: [Qemu-devel] [PATCH v2 26/74] pc: acpi: memhp: move MHPD._STA method into SSDT

[Michael S. Tsirkin]

On Wed, Dec 16, 2015 at 03:47:35PM +0100, Igor Mammedov wrote:
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
> v2:
>  - add parentheses around ifctx block
>    Suggested-by: Marcel Apfelbaum <address@hidden>
> ---
>  hw/acpi/memory_hotplug_acpi_table.c | 14 ++++++++++++++
>  hw/i386/acpi-dsdt-mem-hotplug.dsl   |  8 --------
>  2 files changed, 14 insertions(+), 8 deletions(-)
> 
> diff --git a/hw/acpi/memory_hotplug_acpi_table.c 
> b/hw/acpi/memory_hotplug_acpi_table.c
> index 9b61b1c..e1a6551 100644
> --- a/hw/acpi/memory_hotplug_acpi_table.c
> +++ b/hw/acpi/memory_hotplug_acpi_table.c
> @@ -29,11 +29,25 @@ void build_memory_hotplug_aml(Aml *ctx, uint32_t nr_mem,
>  {
>      Aml *pci_scope;
>      Aml *ctrl_dev;
> +    Aml *method;
> +    Aml *ifctx;
> +    Aml *a_zero = aml_int(0);
> +    Aml *a_slots_nr = aml_name(stringify(MEMORY_SLOTS_NUMBER));
>  
>      /* scope for memory hotplug controller device node */
>      pci_scope = aml_scope("_SB.PCI0");
>      ctrl_dev = aml_scope(stringify(MEMORY_HOTPLUG_DEVICE));
>      {
> +        /* MHPD._STA() method */

You know something's wrong if you are documenting C using ASL.  In this
case, rename ctrl_dev to mem_hotplug_dev, move ifctx zero and slots nr
within {} and drop a_ prefix for zero and slots_nr and code will be
clear without this comment.

> +        method = aml_method("_STA", 0, AML_NOTSERIALIZED);
> +        ifctx = aml_if(aml_equal(a_slots_nr, a_zero));
> +        {
> +             aml_append(ifctx, aml_return(a_zero));
> +        }
> +        aml_append(method, ifctx);
> +        /* present, functioning, decoding, not shown in UI */
> +        aml_append(method, aml_return(aml_int(0xB)));
> +        aml_append(ctrl_dev, method);


Simple unserialized methods that return value depending on input
being zero seem very common.  How about a helper for this case?

E.g.

aml_method_if_then_else(slots_nr, aml_int(0xB), aml_int(0));


>      }
>      aml_append(pci_scope, ctrl_dev);
>      aml_append(ctx, pci_scope);
> diff --git a/hw/i386/acpi-dsdt-mem-hotplug.dsl 
> b/hw/i386/acpi-dsdt-mem-hotplug.dsl
> index c2bb6a1..b4eacc9 100644
> --- a/hw/i386/acpi-dsdt-mem-hotplug.dsl
> +++ b/hw/i386/acpi-dsdt-mem-hotplug.dsl
> @@ -35,14 +35,6 @@
>              External(MEMORY_SLOT_OST_EVENT, FieldUnitObj) // _OST event 
> code, write only
>              External(MEMORY_SLOT_OST_STATUS, FieldUnitObj) // _OST status 
> code, write only
>  
> -            Method(_STA, 0) {
> -                If (LEqual(MEMORY_SLOTS_NUMBER, Zero)) {
> -                    Return(0x0)
> -                }
> -                /* present, functioning, decoding, not shown in UI */
> -                Return(0xB)
> -            }
> -
>              Mutex (MEMORY_SLOT_LOCK, 0)
>  
>              Method(MEMORY_SLOT_SCAN_METHOD, 0) {
> -- 
> 1.8.3.1