Re: [libvirt] [PATCH v5 1/3] add new virDomainCoreDumpWithFormat API

On Wed, Mar 12, 2014 at 09:29:55AM -0600, Eric Blake wrote: > On 03/12/2014 09:04 AM, Martin Kletzander wrote: >> On Thu, Mar 06, 2014 at 09:35:47AM +0000, qiaonuohan(a)cn.fujitsu.com wrote: >>> --memory-only option is introduced without compression supported. Therefore, >>> this is a freature regression of virsh dump. Now qemu has support dumping memory >> >> s/freature/feature/ >> >> but I would not use the word "regression" since that never worked. >> Also it would help mentioning the commit ID or a version it >> got included in qemu. On that note, is there a possibility of >> of introspection of that feature, so we can gracefully error out in >> case older qemu is used? > > Yes - qemu 2.0 is adding 'query-dump-guest-memory-capability', which can > be used for two purposes: 1. if this command exists, 'dump-guest-memory' > supports the new optional 'format' argument; and 2. calling this command > will return a list of WHICH formats are supported by the given qemu > binary (since configure-time choices can disable some of the formats > from actually working). So you need to have a patch that modifies > src/qemu/qemu_capabilities.[ch] to do the probing and set capability > bits, so that we can gracefully error out when talking to a too-old > qemu, or requesting a format that was not compiled in to a new qemu. > Great. Could we have the compression parameter just as an arbitrary string then (properly checked for, etc.) so there is no need to adapt our code to qemu format additions? > >> >> Looking at the rest, I rather fixed what I wanted to change in my repo >> and here's the diff I'd squash in. Let me know if you're OK with >> that. I'll still want an ACK from someone in order to push that, >> though. And feel free to ask about that changes as well. > > I suppose the capability detection could be done as an add-on patch, but > I'm personally thinking it's better to hold off on this series until ALL > the work is done, so we don't forget to do the capability detection work. > Definitely, I just asked this question in the wrong patch, the detection and use of the capability should be in 2/3 or in separate one. Martin