Re: [Xen-devel] [PATCH]libxl: allow to set more than 31 vcpus

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Zhang, Yang Z writes ("RE: [Xen-devel] [PATCH]libxl: allow to set more than 31 
vcpus"):
> Ian Jackson [mailto:Ian.Jackson@xxxxxxxxxxxxx]:
> > This error handling should really go away.  Would you be able to
> > provide a patch to make libxl_cpumap_alloc use libxl__zalloc(NULL, ) ?
> > That never fails, so that would also mean libxl_cpumap_alloc can't
> > fail.
> 
> I don't think so. Libxl_cpumap_alloc() also returned error when
> max_cpus equal zero. So the error handling cannot be avoid even
> using libxl__zalloc.

Hmm.  Can it not be made to either abort or succeed in this case ?

> > > diff -r c6bde42c8845 -r b1229c220984 tools/libxl/libxl_dom.c
> > > --- a/tools/libxl/libxl_dom.c   Thu Apr 12 14:01:27 2012 +0100
> > > +++ b/tools/libxl/libxl_dom.c   Fri May 04 10:47:00 2012 +0800
> > > @@ -146,7 +146,8 @@ int libxl__build_post(libxl__gc *gc, uin
> > >      ents[11] = libxl__sprintf(gc, "%lu", state->store_mfn);
> > >      for (i = 0; i < info->max_vcpus; i++) {
> > >          ents[12+(i*2)]   = libxl__sprintf(gc, "cpu/%d/availability", i);
> > > -        ents[12+(i*2)+1] = (i && info->cur_vcpus && !(info->cur_vcpus & 
> > > (1
> > << i)))
> > > +        ents[12+(i*2)+1] = (i && info->avail_vcpus.size
> > > +
> > && !libxl_cpumap_test(&info->avail_vcpus, i))
> > >                              ? "offline" : "online";
> > 
> > If libxl_cpumap_test returned 0 if cpumap==NULL then this would be
> > simpler.
> 
> Sorry. What your mean for this?

I mean that if you changed libxl_cpumap_test to tolerate a NULL cpumap
and simply return false, then the caller wouldn't have to check for
it.  But you may prefer to keep it the current way.

Ian.

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