Re: [Xen-devel] [PATCH v2] libxl: Handle xen_platform_pci=0 case with qemu-xen.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-11-27 at 18:21 +0000, Anthony PERARD wrote:
> This should result in QEMU *not* adding the xen-platform device.
> 
> Since QEMU 1.6, this can be achieved by using a different qemu machine.
> The one used by libxl is "xenfv", but using QEMU >=1.6 with "-machine
> pc,accel=xen" works as well with only one difference compared to
> "xenfv", there is no xen-platform device.
> 
> Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> ---
>  tools/libxl/libxl_dm.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
> index be39a62..ea773b3 100644
> --- a/tools/libxl/libxl_dm.c
> +++ b/tools/libxl/libxl_dm.c
> @@ -608,7 +608,8 @@ static char ** 
> libxl__build_device_model_args_new(libxl__gc *gc,
>      }
>      for (i = 0; b_info->extra && b_info->extra[i] != NULL; i++)
>          flexarray_append(dm_args, b_info->extra[i]);
> -    flexarray_append(dm_args, "-M");
> +
> +    flexarray_append(dm_args, "-machine");

I trust that -M and -machine are synonyms which go back at least as far
as the versions of qemu we care about?

If so then:
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

I presume that xen_platform_pci=0 will simply fail with a qemu < 1.6?
Perhaps it is worth mentioning this in the xl.cfg man page?

>      switch (b_info->type) {
>      case LIBXL_DOMAIN_TYPE_PV:
>          flexarray_append(dm_args, "xenpv");
> @@ -616,7 +617,14 @@ static char ** 
> libxl__build_device_model_args_new(libxl__gc *gc,
>              flexarray_append(dm_args, b_info->extra_pv[i]);
>          break;
>      case LIBXL_DOMAIN_TYPE_HVM:
> -        flexarray_append(dm_args, "xenfv");
> +        if (!libxl_defbool_val(b_info->u.hvm.xen_platform_pci)) {
> +            /* Switching here to the machine "pc" which does not add
> +             * the xen-platform device instead of the default "xenfv" 
> machine.
> +             */
> +            flexarray_append(dm_args, "pc,accel=xen");
> +        } else {
> +            flexarray_append(dm_args, "xenfv");
> +        }
>          for (i = 0; b_info->extra_hvm && b_info->extra_hvm[i] != NULL; i++)
>              flexarray_append(dm_args, b_info->extra_hvm[i]);
>          break;



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