Re: [Xen-devel] [PATCH 32 of 32 RFC] libxl: Default to stub device model whenever possible

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 16 Jan 2012, Ian Campbell wrote:
> # HG changeset patch
> # User Ian Campbell <ian.campbell@xxxxxxxxxx>
> # Date 1326715929 0
> # Node ID 953a1ce643856edcf9fbbbc2680690b3a26dede8
> # Parent  a2dc899d0f229d82baca92a06b3b7a5b4d918324
> libxl: Default to stub device model whenever possible.

Considering that stubdoms are not yet at feature parity I don't think we
should make this change for 4.2.
At the very least we should expand the set of conditions on which we base
the decision on: certainly the presence of an audio device, maybe pci
passthrough and the type of block backend (considering that some of them
go through qemu now) in case they aren't working properly.


> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> 
> diff -r a2dc899d0f22 -r 953a1ce64385 tools/libxl/libxl_create.c
> --- a/tools/libxl/libxl_create.c      Mon Jan 16 11:33:18 2012 +0000
> +++ b/tools/libxl/libxl_create.c      Mon Jan 16 12:12:09 2012 +0000
> @@ -94,7 +94,20 @@ int libxl__domain_build_info_setdefaults
>          b_info->device_model_version =
>              LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
>  
> -    libxl_defbool_setdefault(&b_info->device_model_stubdomain, false);
> +    /* Default to stub domain device model if possible */
> +    if (b_info->type == LIBXL_DOMAIN_TYPE_HVM
> +        && b_info->device_model_version
> +        == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL
> +        && access(libxl__stubdom_kernel(gc), R_OK) == 0) {
> +        libxl_defbool_setdefault(&b_info->device_model_stubdomain, true);
> +    } else {
> +        libxl_defbool_setdefault(&b_info->device_model_stubdomain, false);
> +    }
> +
> +    if (b_info->device_model_version !=
> +        LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL &&
> +        libxl_defbool_val(b_info->device_model_stubdomain))
> +        return ERROR_INVAL;
>  
>      if (!b_info->max_vcpus)
>          b_info->max_vcpus = 1;
> diff -r a2dc899d0f22 -r 953a1ce64385 tools/libxl/libxl_dm.c
> --- a/tools/libxl/libxl_dm.c  Mon Jan 16 11:33:18 2012 +0000
> +++ b/tools/libxl/libxl_dm.c  Mon Jan 16 12:12:09 2012 +0000
> @@ -686,6 +686,11 @@ retry_transaction:
>      return 0;
>  }
>  
> +char *libxl__stubdom_kernel(libxl__gc *gc)
> +{
> +    return libxl__abs_path(gc, "ioemu-stubdom.gz", 
> libxl_xenfirmwaredir_path());
> +}
> +
>  static int libxl__create_stubdom(libxl__gc *gc,
>                                   int guest_domid,
>                                   libxl_domain_config *guest_config,
> @@ -729,8 +734,7 @@ static int libxl__create_stubdom(libxl__
>      dm_config.b_info.target_memkb = dm_config.b_info.max_memkb;
>  
>      dm_config.b_info.type = LIBXL_DOMAIN_TYPE_PV;
> -    dm_config.b_info.u.pv.kernel.path = libxl__abs_path(gc, 
> "ioemu-stubdom.gz",
> -                                              libxl_xenfirmwaredir_path());
> +    dm_config.b_info.u.pv.kernel.path = libxl__stubdom_kernel(gc);
>      dm_config.b_info.u.pv.cmdline = libxl__sprintf(gc, " -d %d", 
> guest_domid);
>      dm_config.b_info.u.pv.ramdisk.path = "";
>      dm_config.b_info.u.pv.features = "";
> diff -r a2dc899d0f22 -r 953a1ce64385 tools/libxl/libxl_internal.h
> --- a/tools/libxl/libxl_internal.h    Mon Jan 16 11:33:18 2012 +0000
> +++ b/tools/libxl/libxl_internal.h    Mon Jan 16 12:12:09 2012 +0000
> @@ -482,6 +482,8 @@ _hidden int libxl__create_device_model(l
>                                libxl_domain_config *guest_config,
>                                libxl__domain_build_state *state,
>                                libxl__spawner_starting **starting_r);
> +_hidden char *libxl__stubdom_kernel(libxl__gc *gc);
> +
>  _hidden int libxl__create_xenpv_qemu(libxl__gc *gc, uint32_t domid,
>                                libxl_domain_config *guest_config,
>                                libxl__domain_build_state *state,
> 
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