Re: [Qemu-devel] [Xen-devel] [PATCH] libxl: change default QEMU machine to pc-i440fx-1.6

[Fabio Fantoni <fabio.fantoni@m2r.biz>]

Il 23/05/2014 18:07, Stefano Stabellini ha scritto:
> Choose pc-i440fx-1.6 instead of pc for HVM guests, so that we know for
> sure what is the machine that we are emulating.
>
> Use pc-i440fx-1.6 regardless of the xen_platform_pci option. Add the
> xen-platform device if requested. Choose slot 2 for the xen-platform
> device for compatibility with current installations. In case of Intel
> graphic passthrough, slot 2 might be needed by the grafic card. However
> now that we can specify the slot explicitly, it is easy to change the
> position of the xen-platform device on the PCI bus if graphic
> passthrough is enabled.
>
> Move the machine options earlier, before any other emulated devices
> options. Otherwise the selected PCI slot for the xen-platform device is
> not available in QEMU.
>
> Specify PIIX4_PM.acpi-pci-hotplug-with-bridge-support=off, because
> differently from xenfv, the other QEMU machines do not have that option
> off by default.
>
> This patch does not change the emulated environment in the guest.
>
> Refer to this thread: http://marc.info/?l=xen-devel&m=140023775929625&w=2
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
>
> diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
> index 8abed7b..fef684f 100644
> --- a/tools/libxl/libxl_dm.c
> +++ b/tools/libxl/libxl_dm.c
> @@ -476,6 +476,29 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
>           flexarray_vappend(dm_args, "-k", keymap, NULL);
>       }
>   
> +    flexarray_append(dm_args, "-machine");
> +    switch (b_info->type) {
> +    case LIBXL_DOMAIN_TYPE_PV:
> +        flexarray_append(dm_args, "xenpv");
> +        for (i = 0; b_info->extra_pv && b_info->extra_pv[i] != NULL; i++)
> +            flexarray_append(dm_args, b_info->extra_pv[i]);
> +        break;
> +    case LIBXL_DOMAIN_TYPE_HVM:
> +        flexarray_append(dm_args, "pc-i440fx-1.6,accel=xen");
> +        flexarray_append(dm_args, "-global");
> +        flexarray_append(dm_args, "PIIX4_PM.acpi-pci-hotplug-with-bridge-support=off");

I think is good add a comment for remember to remove this workaround 
when pc >=2.1 will be the default since qemu 2.1 will fix it.
https://lists.gnu.org/archive/html/qemu-devel/2014-05/msg04789.html

> +        if (libxl_defbool_val(b_info->u.hvm.xen_platform_pci)) {
> +            flexarray_append(dm_args, "-device");
> +            flexarray_append(dm_args, "xen-platform,addr=0x2");

The fixed pci address to 0x2 probably is a problem with intel gpu 
passthrough:
http://lists.gnu.org/archive/html/qemu-devel/2014-05/msg03726.html

> +        }
> +        for (i = 0; b_info->extra_hvm && b_info->extra_hvm[i] != NULL; i++)
> +            flexarray_append(dm_args, b_info->extra_hvm[i]);
> +        break;
> +    default:
> +        abort();
> +    }
> +
> +
>       if (b_info->type == LIBXL_DOMAIN_TYPE_HVM) {
>           int ioemu_nics = 0;
>   
> @@ -645,29 +668,6 @@ 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, "-machine");
> -    switch (b_info->type) {
> -    case LIBXL_DOMAIN_TYPE_PV:
> -        flexarray_append(dm_args, "xenpv");
> -        for (i = 0; b_info->extra_pv && b_info->extra_pv[i] != NULL; i++)
> -            flexarray_append(dm_args, b_info->extra_pv[i]);
> -        break;
> -    case LIBXL_DOMAIN_TYPE_HVM:
> -        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;
> -    default:
> -        abort();
> -    }
> -
>       ram_size = libxl__sizekb_to_mb(b_info->max_memkb - b_info->video_memkb);
>       flexarray_append(dm_args, "-m");
>       flexarray_append(dm_args, libxl__sprintf(gc, "%"PRId64, ram_size));
>
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