On Wed, 15 Feb 2012 18:39:31 +0100 Jan Kiszka <jan.kis...@siemens.com> wrote:
> On 2012-02-15 18:23, Luiz Capitulino wrote: > > On Wed, 15 Feb 2012 14:34:52 +0100 > > Jan Kiszka <jan.kis...@siemens.com> wrote: > > > >> On 2012-02-15 13:49, Luiz Capitulino wrote: > >>> On Wed, 15 Feb 2012 09:59:07 +0100 > >>> Jan Kiszka <jan.kis...@siemens.com> wrote: > >>> > >>>> On 2012-02-10 20:31, Luiz Capitulino wrote: > >>>>> This is a rebase of Anthony's conversion, from his glib branch; and > >>>>> this is > >>>>> also the beginning of the conversion of complex commands to the qapi. > >>>>> > >>>>> There are two important changes that should be observed: > >>>>> > >>>>> 1. patch 5/6 purges the 'mon' object from migration code. One of the > >>>>> consequences is that we lose the ability to print progress status to > >>>>> the HMP user (esp. in block migration) > >>>> > >>>> This smells extremely fishy. You have some common "monitor" context in > >>>> both cases, means something that decides where suspend/resume takes > >>>> effect or where to pick up file descriptors from. If the exiting Monitor > >>>> object is not generic enough, introduce some super-class and use that in > >>>> common services. Or make sure that a variant of Monitor is also valid > >>>> over QMP. But don't remove the dependency from the API, while > >>>> reintroducing it via the backdoor of cur_mon. > >>> > >>> What we really want to do here is to untangle HMP and QMP. Unfortunately, > >>> the migrate command is one of those commands where the two are deeply > >>> tangled and the split won't be perfect. > >>> > >>> However, the two cases you mention above are solvable: > >>> > >>> 1. suspend/resume: this is *really* a HMP feature and shouldn't be in any > >>> QMP code path. This is correctly addressed in this series by moving it > >>> to hmp_migrate() > >> > >> Almost correctly. ;) > > > > Well, it was moved to the right place :) > > (see the other thread) Yeah, I saw it and will fix the problems you've pointed out. > >>> 2. file descriptor passing: the new QMP server will support sessions and > >>> we'll move statefull commands (like getfd) to it. When we do it, we'll > >>> introduce a new API to get fds that won't depend on the monitor. > >>> However, > >>> this requires all commands to be converted to the qapi first. > >>> Meanwhile > >>> we use the qemu_get_fd() API. > >>> > >>> Note: qemu_get_fd() is temporary, it shouldn't be a problem to use it > >>> (if it's not incorrect, of course, I honestly haven't fully tested it > >>> yet). > >> > >> So there will be a common super-class of Monitor and that new QMP > >> session that also manages the file descriptors? That would make sense. > > > > Oh, yes. Now I see that you said exactly that earlier. Sorry for more or > > less > > re-stating it. > > > >> Still, there would be monitor_get_fd and qmp_get_fd then not > >> qemu_get_fd. I think that should be done already. > > > > The problem is that monitor_get_fd() already exists and qmp_get_fd() > > doesn't make much sense (as this is not related to QMP right now). So, > > I could call it monitor_get_fd_cur() or something like this. > > What object represent a QMP session now? We don't exactly have the notion of a QMP session today, but all QMP state is currently stored in the Monitor object. > That object will once hold the > reference to the FDs. So some qmp_get_fd will take that session and > return the requested fd - so, it does make sense, long-term at least. Yes. Actually most of the code has already been written by Anthony: git://repo.or.cz/qemu/aliguori.git glib (look at qmp-core.c) What I'm doing is to rebase it, do some integration work & fix ups. > In any case, as long as everyone can mess with cur_mon, you don't need > to introduce wrappers that just link a normal monitor service with that > variable. So, you're suggestion to just use monitor_get_fd(), right?
