Re: [Xen-devel] [PATCH 5/6] libxl: allow a generation ID to be specified at domain creation

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-06-11 at 11:53 +0100, David Vrabel wrote:
> On 11/06/14 09:22, Ian Campbell wrote:
> > On Tue, 2014-06-10 at 18:59 +0100, David Vrabel wrote:
> >> On 10/06/14 12:01, Ian Campbell wrote:
> >>> On Tue, 2014-06-03 at 14:15 +0100, David Vrabel wrote:
> >>> Should we consider calling the API field name something more specific,
> >>> like "ms_vgid"? I'm thinking of the case where some other OS vendor
> >>> reinvents the wheel. (I don't care about the internals, just the API).
> >>
> >> generation_id matches the platform/generation-id xenstore key so I would
> >> keep the libxl field name as-is.
> > 
> > One is an internal implementation detail (we can update libx? and
> > hvmloader in parallel if we have to) while the other is a stable API.
> 
> The specification is for a generic, non-Microsoft specific ACPI device
> so I don't see the need to include ms_ in the field name.

The name should reflect the spec then. acpi_vm_gen_counter perhaps
(matching the ACPI _CID)

> >>> Do you not need to worry about endianess when memcpy'ing out of a uuid?
> >>
> >> No. The conversion of uuid to the two 64-bit integers is arbitrary, it
> >> need only be consistent.  The integers in guest memory are in native
> >> endianness.
> > 
> > OK. I was wondering if we might want to preserve the byte order so as
> > not to trample any UUID format which is used.
> 
> The specification doesn't require that the ID is a UUID.

True. It does say "cryptographically random integer value". Are you sure
that the result of libxl_uuid_generate meets that standard (rather than
say one of the non-crypto schemes for generating uniqueness)?

Ian.



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