Re: [Xen-devel] [PATCH v7 04/11] public: xen.h: add definitions for UUID handling

[Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>]

Hi Julien,

On 10.10.17 18:19, Julien Grall wrote:
> Hi,
>
> On 09/10/17 10:40, George Dunlap wrote:
> > On 10/05/2017 03:50 PM, Volodymyr Babchuk wrote:
> > > Hi Konrad,
> > >
> > > On 05.10.17 16:03, Konrad Rzeszutek Wilk wrote:
> > > > On Thu, Oct 05, 2017 at 12:00:20AM +0300, Volodymyr Babchuk wrote:
> > > > > Added type xen_uuid_t. This type represents UUID as an array of 16
> > > > > bytes in big endian format.
> > > > >
> > > > > Added macro XEN_DEFINE_UUID that constructs UUID in the usual way:
> > > > >
> > > > >    XEN_DEFINE_UUID(0x00112233, 0x4455, 0x6677, 0x8899,
> > > > >          0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff)
> > > > >
> > > > > will construct UUID 00112233-4455-6677-8899-aabbccddeeff presented as
> > > > >    {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88,
> > > > >     0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff}
> > > > >
> > > > > NB: This is compatible with Linux kernel and with libuuid, but it 
> > > > > is not
> > > > > compatible with Microsoft, as they use mixed-endian encoding (some
> > > > > components are little-endian, some are big-endian).
> > > > Oh boy. What a mess.
> > > >
> > > > Do we care about Microsoft for this or is this more for information
> > > > purpose?
> > > This is for information. Problem is that XEN already defines EFI_GUID
> > > which uses MS-style encoding. It is used in EFI code only, but I think
> > > it is worth to explain differences.
> > > There was discussion at [1]
> > > [...]
> > >
> > > [1] http://markmail.org/message/cawi6f33spqg4hf5
> > So did you perhaps mean to say something like this:
> >
> > "NB: We define a new structure here rather than re-using EFI_GUID.
> > EFI_GUID uses a Microsoft-style encoding which, among other things,
> > mixes little-endian and big-endian.  The structure defined in this
> > patch, unlike EFI_GUID, is compatible with the Linux kernel and libuuid."
> Volodymyr, do you have any opinions here?
>
> This is basically the last patch that needs to be acked before merged 
> (thought there are few nits to fix). I would really like to see this 
> patch merged before the code freeze tomorrow.
I'm perfectly fine with proposed comment.

I'm preparing v8 right now.

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