Re: [PATCH 15/15] xen: tools: expose EPC in ACPI table

["Huang, Kai" <kai.huang@linux.intel.com>]

On 7/12/2017 11:05 PM, Andrew Cooper wrote:
> On 09/07/17 10:16, Kai Huang wrote:
>> On physical machine EPC is exposed in ACPI table via "INT0E0C". 
>> Although EPC
>> can be discovered by CPUID but Windows driver requires EPC to be 
>> exposed in
>> ACPI table as well. This patch exposes EPC in ACPI table.
> 
> :(
> 
>> diff --git a/tools/libacpi/dsdt.asl b/tools/libacpi/dsdt.asl
>> index fa8ff317b2..25ce196028 100644
>> --- a/tools/libacpi/dsdt.asl
>> +++ b/tools/libacpi/dsdt.asl
>> @@ -441,6 +441,55 @@ DefinitionBlock ("DSDT.aml", "DSDT", 2, "Xen", 
>> "HVM", 0)
>>                   }
>>               }
>>           }
>> +
>> +        Device (EPC)
> 
> Would it not be better to put this into an SSDT, and only expose it to 
> the guest if SGX is advertised?

You mean to create dedicated ssdt_epc.asl? I thought about this, but I 
am not quite sure if we can, because new EPC device will need to refer 
\_SB.EMIN, and \_SB.ELEN, which are in acpi_info, to get EPC base and 
size. Can we refer acpi_info in dedicated ssdt_epc.asl?

Thanks,
-Kai

> 
> ~Andrew
> 
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