Re: [libvirt] [PATCH v2] qemu: better error message when block job can't succeed

https://bugzilla.redhat.com/show_bug.cgi?id=1140981 reports that the qemu-kvm shipped as part of RHEL 7.0 intentionally cripples block jobs by removing the 'block-stream' QMP command, but that our probe for whether block jobs work was merely whether 'block-job-cancel' exists. As the crippling did not remove job cancellation, we end up trying the qemu command and printing an ugly message: error: Requested operation is not valid: Command 'block-stream' is not found even though our code base was already prepared to print a nice message that jobs are unsupported: error: unsupported configuration: block jobs not supported with this qemu binary Doing one more QMP probe lets us match the reality of crippled qemu. Yes, we really have to cater to two spellings of the command, due to older upstream qemu. * src/qemu/qemu_capabilities.h (QEMU_CAPS_BLOCK_STREAM): New probe. * src/qemu/qemu_capabilities.c (virQEMUCapsProbeQMPCommands): Kill block jobs with nice error message if qemu is crippled. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- src/qemu/qemu_capabilities.c | 11 +++++++++++ src/qemu/qemu_capabilities.h | 1 + 2 files changed, 12 insertions(+)