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

[Shivaprasad G Bhat]

On 09/06/2016 05:56 PM, Peter Krempa wrote:
> On Tue, Sep 06, 2016 at 16:59:09 +0530, 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 |   28 +++++++++++++++++++++++++---
>>   1 file changed, 25 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/virsh-host.c b/tools/virsh-host.c
>> index 57f0c0e..505cfbb 100644
>> --- a/tools/virsh-host.c
>> +++ b/tools/virsh-host.c
>> @@ -607,16 +607,38 @@ cmdMaxvcpus(vshControl *ctl, const vshCmd *cmd)
>>   {
>>       const char *type = NULL;
>>       int vcpus;
>> +    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;
>>   
>> -    if ((vcpus = virConnectGetMaxVcpus(priv->conn, type)) < 0)
>> -        return false;
>> +    caps = virConnectGetDomainCapabilities(priv->conn, NULL, NULL, NULL, type, flags);
>> +    if (caps) {
>> +        xml = virXMLParseStringCtxt(caps, _("(domainCapabilities)"), &ctxt);
>> +        if (!xml) {
>> +            VIR_FREE(caps);
>> +            return false;
>> +        }
>>   
>> -    vshPrint(ctl, "%d\n", vcpus);
>> +        virXPathInt("string(./vcpu[1]/@max)", ctxt, &vcpus);
> This doesn't handle the case when the capability XML does not contain
> the required data. This still should fall back to the legacy approach.
Ah bhyve doesn't report the vcpus in domcapabilities. Thanks. Fixed it 
in next version I posted just now.

Regards,
Shivaprasad
> Additionally virXPathInt does not initialize vcpus on failure and since
> it's not initialized when declared this would trigger a compiler
> warning.
>
>> +        xmlXPathFreeContext(ctxt);
>> +        xmlFreeDoc(xml);
>> +        VIR_FREE(caps);