On 06/12/2015 03:49 PM, Michal Privoznik wrote: > During a review, I've noticed this error message that was eventually > produced when I was trying to define a domain: > > error: invalid argument: could not find capabilities for arch=mips64el > domaintype=(null) > > Look at the (null). Why is it there? Well, during XML parsing, we try > to look up the default emulator for given OS type and possibly virt > type too. And this is the problem, because if we don't want to look up > by virt type, a -1 is passed to note this fact. Later, the code > handles -1 just right. Except for error message. When it is > constructed (in a very fabulous way I must say), the value is compared > to zero, not -1. And since we don't have any translation from -1 to a > virt type string, we just print (null). > > Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; > --- > src/conf/capabilities.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/src/conf/capabilities.c b/src/conf/capabilities.c > index 6decde8..9c2c6b4 100644 > --- a/src/conf/capabilities.c > +++ b/src/conf/capabilities.c > @@ -678,7 +678,7 @@ virCapabilitiesDomainDataLookupInternal(virCapsPtr caps, > virDomainOSTypeToString(ostype)); > if (arch) > virBufferAsprintf(&buf, "arch=%s ", virArchToString(arch)); > - if (domaintype) > + if (domaintype != -1) Well, this will work. However for some reason I don't quite like this way of handling it. We're trying to construct an error message and because we didn't want to search by virttype we special-case this. I was thinking more about introducing a new enum VIR_DOMAIN_VIRT_NONE which will serve exactly this purpose (see virCapsDomainDataCompare, comparison to arch :)). That way, we don't have to play with ternary in here as pass VIRT_NONE right away: ...if (!(capsdata = virCapabilitiesDomainDataLookup(caps, def->os.type, def->os.arch, use_virttype ? def->virtType : -1, NULL, NULL)))... Since XML parsing requires a domain to have a valid virttype defined, we should be able to abuse the VIRT_NONE this way and stay a little consistent in this particular code snippet of constructing an error message. What do you think about it? If you think it's not worth it at all, just drop the idea and push this one, it's an ACK.