Re: [Xen-devel] [PATCH 1 of 3] To be able to support arbitrary numbers of physical cpus it was necessary to

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2010-10-06 at 12:21 +0100, Stefano Stabellini wrote:
> On Tue, 5 Oct 2010, Juergen Gross wrote:
> > diff -r fe3018c6976d -r cfce8e755505 tools/libxl/libxl_internal.h
> > --- a/tools/libxl/libxl_internal.h  Mon Oct 04 12:52:14 2010 +0100
> > +++ b/tools/libxl/libxl_internal.h  Tue Oct 05 14:19:13 2010 +0200
> > @@ -239,7 +239,6 @@
> >  _hidden char *libxl__domid_to_name(libxl__gc *gc, uint32_t domid);
> >  _hidden char *libxl__poolid_to_name(libxl__gc *gc, uint32_t poolid);
> >  
> > -
> >    /* holds the CPUID response for a single CPUID leaf
> >     * input contains the value of the EAX and ECX register,
> >     * and each policy string contains a filter to apply to
> 
> we don't need this change
> 
> 
> > diff -r fe3018c6976d -r cfce8e755505 tools/libxl/xl_cmdimpl.c
> > --- a/tools/libxl/xl_cmdimpl.c      Mon Oct 04 12:52:14 2010 +0100
> > +++ b/tools/libxl/xl_cmdimpl.c      Tue Oct 05 14:19:13 2010 +0200
> > @@ -3616,12 +3616,11 @@
> >  static void vcpupin(char *d, const char *vcpu, char *cpu)
> >  {
> >      libxl_vcpuinfo *vcpuinfo;
> > -    libxl_physinfo physinfo;
> >      uint64_t *cpumap = NULL;
> >  
> >      uint32_t vcpuid, cpuida, cpuidb;
> >      char *endptr, *toka, *tokb;
> > -    int i, nb_vcpu, cpusize;
> > +    int i, nb_vcpu, cpusize, cpumapsize;
> >  
> >      vcpuid = strtoul(vcpu, &endptr, 10);
> >      if (vcpu == endptr) {
> > @@ -3634,12 +3633,13 @@
> >  
> >      find_domain(d);
> >  
> > -    if (libxl_get_physinfo(&ctx, &physinfo) != 0) {
> > -        fprintf(stderr, "libxl_get_physinfo failed.\n");
> > +    if ((cpusize = xc_get_max_cpus(ctx.xch)) == 0) {
> > +        fprintf(stderr, "xc_get_maxcpus failed.\n");
> >          goto vcpupin_out1;
> >      }
> 
> You shouldn't be calling xc functions directly from xl_cmdimpl.c.
> The basic rule is: libxl clients (such as xl) shouldn't need to call any
> library functions other than libxenlight's functions.
> You can add a libxl_get_max_cpus function though.

Maybe we should add libxl_cpumap_alloc_phys which returns a libxl_cpumap
big enough to hold all physical CPUs, there are a few places within
libxl itself which might benefit from this, e.g. libxl_list_cpupool and
libxl_list_vcpu both call xc_get_max_cpus and then use the result as a
parameter to libxl_cpumap_alloc.

Actually, given that libxl_cpumap is only ever used for PCPUs perhaps
alloc should just always return a suitably sized map and there's no need
for the size parameter to libxl_cpumap_alloc? Is there any plausible
potential use for a libxl_cpumap of nrVCPU rather than nrPCPU ?

Ian.



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