On 10/11/2011 03:01 PM, Anthony Liguori wrote: > On 10/11/2011 06:48 AM, Avi Kivity wrote: >> On 10/10/2011 01:35 PM, Juan Quintela wrote: >>> Hi >>> >>> Please send in any agenda items you are interested in covering. >>> >> >> Subsections, version numbers, migration to older releases. > > Problem with subsections: > > The encoding of a subsection within an embedded structure is ambiguous > because the subsection occurs at the end of the structure. QEMU may > mistakenly parse what follows the structure as the end of subsection > deliminator. > > Possible solutions: > > 1) Juan has a series that adds heuristics to better match the EOS > deliminator. While not 100% perfect, it should handle practically all > possible cases. > > The main issue is that it's not present in older QEMUs which means > migrating a subsection within a structure to an old QEMU that doesn't > have this heuristic could fail. > > Ways to mitigate: force all devices with subsections to bump their > version number. Wave our hands around and claim that the new version > requires the subsection heuristics to be present. > > 2) Add Paolo's protocol change. This will cause a migration flag > day. Since we want to switch to ASN.1 too, we'll have another flag > day for the next release too. > > 3) Change subsection protocol more dramatically than Paolo's change > (make subsections stand alone sections). Not clear how much effort > this is. > > 4) Avoid subsections until we introduce a new wire protocol based on > ASN.1 that can better handle concepts like subsections. This misses > some opportunity for backwards compatibility in the short term but > avoids repeated flag days. > 5) Implement subsections through the wire as top-level sections (as originally intended). Keep existing subsections with (1). btw, it's reasonable to require that backwards migration is only to a fully updated stable release, so we can do 5) too, or backport 1). -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
