Re: [Xen-devel] [PATCH 1/2] hvmloader: limit CPUs exposed to guests

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 06/16/2016 11:25 AM, Jan Beulich wrote:
>>>> On 16.06.16 at 17:09, <boris.ostrovsky@xxxxxxxxxx> wrote:
>> On 06/16/2016 05:40 AM, Jan Beulich wrote:
>>
>> --- a/tools/firmware/hvmloader/acpi/mk_dsdt.c
>> +++ b/tools/firmware/hvmloader/acpi/mk_dsdt.c
>> @@ -150,6 +150,14 @@ int main(int argc, char **argv)
>>      indent(); printf("MSU, 8\n");
>>      pop_block();
>>  
>> +    /* Processor object helpers. */
>> +    push_block("Method", "PMAT, 2");
>> +    push_block("If", "LLess(Arg0, NCPU)");
>> +    stmt("Return", "ToBuffer(Arg1)");
>> +    pop_block();
>> +    stmt("Return", "Buffer() {0, 8, 0xff, 0xff, 0, 0, 0, 0}");
>>
>>
>> Could you explain what this is? (I suspect  this is related to MAT
>> object and I don't think I understand what it is).
> This is a helper routine for _MAT(), helping greatly to reduce
> overall size of the DSDT. It checks whether the CPU is within the
> range of available ones (online or offline), and if it isn't returns a
> static buffer instead of data read from MADT (as it's the purpose
> of this patch to remove these MADT entries for not present CPUs).

I meant just the last line (I understand what the routine is --- I am
not clear where MAT format is defined).

-boris

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