On Mon, Nov 25, 2013 at 09:43:48AM -0700, Eric Blake wrote: > On 11/25/2013 09:32 AM, Paolo Bonzini wrote: > > >> Yes please. Firing up a calculator to figure out how much is 1G is not > >> friendly, neither is firing it up to figure out what did management do > >> with QMP. It should be a text based interface not a binary one. > > Right now, QMP takes an 'int', which does not allow a suffix. Libvirt > prefers passing a value in 'bytes', rather than risking confusion on > whether a value in G was rounded (up, down? to nearest power of 10 or > power of 2?). Unfortunately, yes, that means you need a calculator when > parsing QMP logs to see whether the 1073741824 passed by libvirt is the > 1G you had in mind. > > HMP, qtest, and any other decent shell around raw QMP is more than > welcome to provide human-usable wrappers that takes "1G" as a string and > turns it into the raw int used by the underlying QMP. In fact, I > encourage it.
How will it know 1G is not e.g. an ID? We can invent rules like "IDs should not start with a number", but these rules are better enforced in a single place for consistency, and it's likely too late to enforce that in HMP. > > This is unfortunately a counter-example to the rule that HMP commands > > should always be implemented in terms of their QMP counterparts. I do > > not believe this is really a problem. It can be fixed later; for now, I > > think "perfect is the enemy of good" applies. > > Hey - I just realized that now that we have anonymous unions, we could > theoretically extend QMP to allow a union between 'int' and 'string' - > if an 'int' is passed, it is in bytes; if a 'string' is passed, then > parse it the way HMP would (so the string "1G" would be equivalent to > the raw int 1073741824). But I don't know if it will help you (libvirt > will still prefer to use raw ints in any QMP log you read off of libvirt > interactions). Yes, I think that would address the issue. > Eric Blake eblake redhat com +1-919-301-3266 > Libvirt virtualization library http://libvirt.org >
