From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH 5/6] libxl: allow a generation ID to be specified at domain creation Date: Wed, 11 Jun 2014 12:47:03 +0100 Message-ID: <539841B7.5050507@citrix.com> References: <1401801340-6196-1-git-send-email-david.vrabel@citrix.com> <1401801340-6196-6-git-send-email-david.vrabel@citrix.com> <1402398065.1250.36.camel@kazak.uk.xensource.com> <5397477B.80801@citrix.com> <1402474966.9559.8.camel@kazak.uk.xensource.com> <53983547.40703@citrix.com> <1402484518.16332.3.camel@kazak.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1Wugzk-0000sj-LN for xen-devel@lists.xenproject.org; Wed, 11 Jun 2014 11:47:08 +0000 In-Reply-To: <1402484518.16332.3.camel@kazak.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell Cc: xen-devel@lists.xenproject.org, Ian Jackson , Stefano Stabellini List-Id: xen-devel@lists.xenproject.org On 11/06/14 12:01, Ian Campbell wrote: > 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) It does match the spec; "Generation ID" is the name of the feature. Using acpi_vm_gen_counter would just be confusing because the device does not provide a counter. >>>>> 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)? Yes (although it does only provide 122 bits of randomness but I think the trade-off of a convenient, UUID-base interface is worth it). David