[libvirt] [PATCH] qemu: don't fail capabilities check on 0.12.x

[Wen Congyang]

At 01/19/2011 12:51 AM, Eric Blake Write:
> Fixes regression introduced in commit 2211518, where all qemu 0.12.x
> fails to start, as does qemu 0.13.x lacking the pci-assign device.
> 
> * src/qemu/qemu_capabilities.c (qemuCapsExtractVersionInfo): Check
> for -device driver,? support.
> (qemuCapsExtractDeviceStr): Avoid failure if all probed devices
> are unsupported.
> Reported by Ken Congyang.
s/Ken/Wen/

This patch seems fine to me.

> ---
> 
>  src/qemu/qemu_capabilities.c |   13 ++++++++++---
>  1 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index 1f0a3c2..faf7d44 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -1048,10 +1048,14 @@ qemuCapsExtractDeviceStr(const char *qemu,
> 
>      /* Cram together all device-related queries into one invocation;
>       * the output format makes it possible to distinguish what we
> -     * need.  Unrecognized '-device bogus,?' cause an error in
> -     * isolation, but are silently ignored in combination with
> -     * '-device ?'.  */
> +     * need.  With qemu 0.13.0 and later, unrecognized '-device
> +     * bogus,?' cause an error in isolation, but are silently ignored
> +     * in combination with '-device ?'.  Qemu 0.12.x doesn't
> +     * understand '-device name,?', and always exits with status 1 for
> +     * the simpler '-device ?', so this function is really only useful
> +     * for parsing out features added in 0.13.0 or later.  */
>      cmd = virCommandNewArgList(qemu,
> +                               "-device", "?",
>                                 "-device", "pci-assign,?",
>                                 "-device", "virtio-blk-pci,?",
>                                 NULL);
> @@ -1119,7 +1123,10 @@ int qemuCapsExtractVersionInfo(const char *qemu,
>                               &version, &is_kvm, &kvm_version) == -1)
>          goto cleanup;
> 
> +    /* Only call qemuCapsExtractDeviceStr for qemu 0.13.0+, since it
> +     * won't set any additional flags for qemu 0.12.x.  */
>      if ((flags & QEMUD_CMD_FLAG_DEVICE) &&
> +        strstr(help, "-device driver,?") &&
>          qemuCapsExtractDeviceStr(qemu, &flags) < 0)
>          goto cleanup;
>