From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH 10/27] docs: Libxl migration v2 stream specification Date: Wed, 8 Jul 2015 14:49:52 +0100 Message-ID: <559D2A80.3040607@citrix.com> References: <1434375880-30914-1-git-send-email-andrew.cooper3@citrix.com> <1434375880-30914-11-git-send-email-andrew.cooper3@citrix.com> <1434463086.13744.173.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1434463086.13744.173.camel@citrix.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: Wei Liu , Yang Hongyang , Ian Jackson , Xen-devel List-Id: xen-devel@lists.xenproject.org On 16/06/2015 14:58, Ian Campbell wrote: > On Mon, 2015-06-15 at 14:44 +0100, Andrew Cooper wrote: >> Signed-off-by: Andrew Cooper >> +EMULATOR\_CONTEXT >> +---------------- >> + >> +A context blob for a specific emulator associated with the domain. >> + >> + 0 1 2 3 4 5 6 7 octet >> + +------------------------+------------------------+ >> + | emulator_id | index | >> + +------------------------+------------------------+ >> + | emulator_ctx | >> + ... >> + +-------------------------------------------------+ >> + >> +-------------------------------------------------------------------- >> +Field Description >> +------------ --------------------------------------------------- >> +emulator_id 0x00000000: Unknown (In the case of a legacy stream) >> + >> + 0x00000001: Qemu Traditional >> + >> + 0x00000002: Qemu Upstream >> + >> + 0x00000003 - 0xFFFFFFFF: Reserved for future emulators. > Would it be useful for future proofing to carve out some space for a > per-emulator version field too? What would that be useful for? It is the emulators problem/fault if it can't read the blob it is given. Superficially, I can see why the field would be nice for debugging purposes, but not all emulators will have a consistent version scheme, and we only install a single version of each emulator. All I can see happening is libxl starting to guess about emulator/blob compatibility, which is absolutely not its place to do. > > Otherwise LGTM. > > One thought, it might be useful (here or elsewhere) to have an explicit > overview of the expected control flow (as in the ownership of the fd, > and/or nesting of the layers as you prefer to think about it) between > libxc, libxl and the next layer (i.e. xl). I will see what I can do, but the freeze is very imminent. ~Andrew