Re: [RFC PATCH v2 01/16] ACPI: Add support for device specific properties

Darren Hart
2014-10-06T16:25:32Z

On 10/6/14, 7:32, "Mika Westerberg" <mika.westerberg@linux.intel.com>
wrote:

>On Mon, Oct 06, 2014 at 02:50:21PM +0100, Grant Likely wrote:
>>
>> > +/* ACPI _DSD device properties UUID:
>>daffd814-6eba-4d8c-8a91-bc9bbf4aa301 */
>> > +static const u8 prp_uuid[16] = {
>> > + 0x14, 0xd8, 0xff, 0xda, 0xba, 0x6e, 0x8c, 0x4d,
>> > + 0x8a, 0x91, 0xbc, 0x9b, 0xbf, 0x4a, 0xa3, 0x01
>> > +};
>>
>> ?
>>
>> What is the encoding used here? I see the first 4 bytes for "daffd814"
>> encoded in little endian (0x14 first), and then the remaining values
>> encoded in big-endian for each number. Is this typical for UUID values?
>
>The buffer format is explained in ACPI 5.1 spec, page 823.
>
>I generated the above so that I compiled a _DSD with correct UUID using
>iASL and then disassambled it with the same tool.
>

I bugged Mika with the same question, it's a fairly non-intuitive encoding
:-)

--
Darren Hart
Intel Open Source Technology Center