Re: type mismatch in SSDT

[Michael S. Tsirkin]

On Thu, Oct 27, 2022 at 03:52:53PM +0200, Igor Mammedov wrote:
> On Thu, 27 Oct 2022 01:59:22 -0400
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > Just noticed this when disassembling:
> > 
> > Parsing completed
> > ACPI Warning: NsLookup: Type mismatch on ODAT (RegionField), searching for 
> > (Buffer) (20210604/nsaccess-760)
> > Disassembly completed
> > ASL Output:    /tmp/old-asl2/tests/data/acpi/virt/SSDT.memhp.dsl - 14945 
> > bytes
> > 
> > Did not look into this yet but it seems new.
> It was there practically 'forever'.
> 
> ODAT should be treated as Buffer according to implicit Field/data conversion 
> rules,
> that's probably the reason why it works. So warning looks a bit bogus to me.
> 
> however:
>   DefCreateByteField := CreateByteFieldOp SourceBuff ByteIndex NameString
>   SourceBuff := TermArg => Buffer
>   TermArg := ExpressionOpcode | DataObject | ArgObj | LocalObj
> 
> and none of that explicitly leads to 
> 
>   TermObj := Object | StatementOpcode | ExpressionOpcode
>   Object := NameSpaceModifierObj | NamedObj
> 
> So if we are to be as pedantic as IASL, we need to supply
> field to CreateByteField not by name but via one of TermArg.
> We could copy/assign whole buffer to a LocalObj
> or summarily use ExpressionOpcode => ToBuffer() // this one has a bit 
> controversial definition in 6.4 spec
> or to avoid any copying add 'useless' DerefOf(RefOf())
> wrapper around name to make argument of ExpressionOpcode kind.
> 
> following should silence warning.
> 
> diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
> index 31e46df0bd..7488007540 100644
> --- a/hw/acpi/nvdimm.c
> +++ b/hw/acpi/nvdimm.c
> @@ -1127,7 +1127,7 @@ static void nvdimm_build_common_dsm(Aml *dev,
>      /* If RLEN >= Integer size, just use CreateField() operator */
>      aml_append(method, aml_store(aml_shiftleft(dsm_out_buf_size, aml_int(3)),
>                                   dsm_out_buf_size));
> -    aml_append(method, aml_create_field(aml_name(NVDIMM_DSM_OUT_BUF),
> +    aml_append(method, 
> aml_create_field(aml_derefof(aml_refof(aml_name(NVDIMM_DSM_OUT_BUF))),
>                 aml_int(0), dsm_out_buf_size, "OBUF"));
>      aml_append(method, aml_return(aml_name("OBUF")));


Thanks! Let's try to raise this with ACPI committee?

-- 
MST