[libvirt] [PATCH v2] virsh: use virConnectGetDomainCapabilities with maxvcpus

[John Ferlan]

On 07/29/2016 09:49 AM, Shivaprasad G Bhat wrote:
> virsh maxvcpus --type kvm output is useless on PPC. Also, in
> commit e6806d79 we documented not rely on virConnectGetMaxVcpus
> output. Fix the  maxvcpus to use virConnectGetDomainCapabilities
> now to make it useful. The call is made to use the default emulator
> binary and to check for the host machine and arch which is what the
> command intends to show anyway.
> 
> Signed-off-by: Shivaprasad G Bhat <sbhat at linux.vnet.ibm.com>
> ---
>  tools/virsh-host.c |   26 ++++++++++++++++++++++++--
>  1 file changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/virsh-host.c b/tools/virsh-host.c
> index 57f0c0e..dd6ff4e 100644
> --- a/tools/virsh-host.c
> +++ b/tools/virsh-host.c
> @@ -606,15 +606,37 @@ static bool
>  cmdMaxvcpus(vshControl *ctl, const vshCmd *cmd)
>  {
>      const char *type = NULL;
> -    int vcpus;
> +    int vcpus = -1;
> +    char *caps = NULL;
> +    const unsigned int flags = 0; /* No flags so far */
> +    xmlDocPtr xml = NULL;
> +    xmlXPathContextPtr ctxt = NULL;
>      virshControlPtr priv = ctl->privData;
>  
>      if (vshCommandOptStringReq(ctl, cmd, "type", &type) < 0)
>          return false;
>  
> +    caps = virConnectGetDomainCapabilities(priv->conn, NULL, NULL, NULL, type, flags);
> +    if (!caps)

I think perhaps a bit of code like virshGetDomainDescription,
cmdDomblkstat, cmdDominfo, virshDomainListCollect, etc. where last_error
is checked for VIR_ERR_NO_SUPPORT, vshResetLibvirtError is called before
falling back...


John
> +        goto fallback;
> +
> +    xml = virXMLParseStringCtxt(caps, _("(domainCapabilities)"), &ctxt);
> +    if (!xml) {
> +        VIR_FREE(caps);
> +        goto fallback;
> +    }
> +
> +    virXPathInt("string(./vcpu[1]/@max)", ctxt, &vcpus);
> +
> +    xmlXPathFreeContext(ctxt);
> +    xmlFreeDoc(xml);
> +    if (vcpus > 0)
> +        goto exit;
> +
> + fallback:
>      if ((vcpus = virConnectGetMaxVcpus(priv->conn, type)) < 0)
>          return false;
> -
> + exit:
>      vshPrint(ctl, "%d\n", vcpus);
>  
>      return true;
> 
> --
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