Re: [PATCH] libxl: Use -vcpu_avail with qemu-xen.

[Ian Campbell <Ian.Campbell@citrix.com>]

On Fri, 2013-05-31 at 17:39 +0100, Anthony PERARD wrote:
> This require the series CPU hotplug for qemu-xen.
> 
> Note: this patch is valid only for 4.3 as the -vcpu_avail will
> probably not be upstream to Qemu.

Ugh. So how are we going to handle this in the future? libxl ideally
needs to work with upstream qemu or our qemu seamlessly, which would
mean needed to know whether to use -vcpu_avail vs. whatever upstream
has. I'd much prefer to make our qemu export the same interface and use
that...

> 
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> ---
>  tools/libxl/libxl_dm.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
> index 1e3a9f4..2db2372 100644
> --- a/tools/libxl/libxl_dm.c
> +++ b/tools/libxl/libxl_dm.c
> @@ -530,11 +530,17 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
>              flexarray_append(dm_args, "-smp");
>              if (b_info->avail_vcpus.size) {
>                  int nr_set_cpus = 0;
> +                char *s;
>                  nr_set_cpus = libxl_bitmap_count_set(&b_info->avail_vcpus);
>  
>                  flexarray_append(dm_args, libxl__sprintf(gc, "%d,maxcpus=%d",
>                                                           nr_set_cpus,
>                                                           b_info->max_vcpus));
> +                
> +                s = libxl_bitmap_to_hex_string(CTX, &b_info->avail_vcpus);
> +                flexarray_vappend(dm_args, "-vcpu_avail",
> +                                  libxl__sprintf(gc, "%s", s), NULL);
> +                free(s);
>              } else
>                  flexarray_append(dm_args, libxl__sprintf(gc, "%d",
>                                                           b_info->max_vcpus));