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

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

[Stefano Stabellini]

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

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

[Fabio Fantoni]

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));
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel

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

[Stefano Stabellini]

On Fri, 23 May 2014, Fabio Fantoni wrote:
> 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

The workaround is not actually harmful, it doesn't need to be removed
when pc >= 2.1 in QEMU.


> > +        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

Right, however we cannot really change the default position of the
xen-platform device on the PCI bus, otherwise we'll end up changing the
emulated environment for all the VMs out there.

I'll leave it to Tiejun to move xen-platform to another slot when
graphic passthrough is enabled.

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

[Fabio Fantoni]

Il 25/05/2014 16:14, Stefano Stabellini ha scritto:
> On Fri, 23 May 2014, Fabio Fantoni wrote:
>> 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");

I think that a note in README should be added: qemu >=1.6.1 is required 
for hvm domUs.

About the other xl parameter to be added I think that should be:
qemu_machine_type="i440fx"|"q35" (when also q35 will be supported on xen)
qemu_machine_version="x.y" to specify the machine version, useful for 
debug/testing and other some cases.

>>> +        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
> The workaround is not actually harmful, it doesn't need to be removed
> when pc >= 2.1 in QEMU.
>
>
>>> +        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
> Right, however we cannot really change the default position of the
> xen-platform device on the PCI bus, otherwise we'll end up changing the
> emulated environment for all the VMs out there.
>
> I'll leave it to Tiejun to move xen-platform to another slot when
> graphic passthrough is enabled.

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

[Stefano Stabellini]

On Wed, 28 May 2014, Paolo Bonzini wrote:
> Il 28/05/2014 18:41, Stefano Stabellini ha scritto:
> > However it would still place xen-platform at slot 3 instead of slot 2 if
> > soundhw is specified. It seems to me that there is not a perfect
> > solution to this problem.  We can either:
> > 
> > - Switch to -machine pc-i440fx-1.6 by default and use consistently the
> > same -machine option no matter the value of xen_platform_pci. Nice, but
> > we break compatibility with existing guests if soundhw is specified.
> > 
> > - Switch to -machine pc-i440fx-1.6 only when xen_platform_pci=0 is
> > specified and keep xenfv if xen_platform_pci=1. We still break
> > compatibility when soundhw is specified together with xen_platform_pci=0.
> 
> - change the implementation of the soundhw option to use -device instead.

Thanks, this sounds like the best option by far.

I noticed that "-soundhw hda" becomes "-device intel-hda".

Given that the VM config file exports a soundhw paramter, we would need
a programmatic way to get the -device command line option from the
soundhw paramter. Is there a way to do that?

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

[Paolo Bonzini]

Il 03/06/2014 15:38, Stefano Stabellini ha scritto:
> Thanks, this sounds like the best option by far.
>
> I noticed that "-soundhw hda" becomes "-device intel-hda".
>
> Given that the VM config file exports a soundhw paramter, we would need
> a programmatic way to get the -device command line option from the
> soundhw paramter. Is there a way to do that?

A table. :)

-soundhw	corresponding -device syntax
---------------------------------------------------------
ac97		-device AC97
adlib		-device adlib
cs4231a		-device cs4231a
es1370		-device ES1370
gus		-device gus
hda		-device intel-hda,id=libxl-intel-hda \
		-device hda-duplex,bus=libxl-intel-hda.0
pcspk		-device isa-pcspk
sb16		-device sb16

(To review it start with "git grep _register_soundhw").

Paolo

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

[Ian Campbell]

On Tue, 2014-06-03 at 14:38 +0100, Stefano Stabellini wrote:
> Given that the VM config file exports a soundhw paramter, 

... as a string.

That sounds like a libxl API mistake to me. libxl should take an enum
for this sort of thing. Then xl should parse whatever strings it likes
(including specific string needed for backward compatibility) into the
appropriate enum values and libxl should generate the correct
corresponding qemu options for whichever version it is using.

libxl will need to keep the existing string field alongside the new enum
field for API compatibility, I suppose it will also need to parse some
legacy values into the enum itself, those probably equate to whatever
qemu -soundhw used to accept.

Icky, but not insurmountable, I think.

Ian.

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

[Fabio Fantoni]

Il 03/06/2014 15:38, Stefano Stabellini ha scritto:
> On Wed, 28 May 2014, Paolo Bonzini wrote:
>> Il 28/05/2014 18:41, Stefano Stabellini ha scritto:
>>> However it would still place xen-platform at slot 3 instead of slot 2 if
>>> soundhw is specified. It seems to me that there is not a perfect
>>> solution to this problem.  We can either:
>>>
>>> - Switch to -machine pc-i440fx-1.6 by default and use consistently the
>>> same -machine option no matter the value of xen_platform_pci. Nice, but
>>> we break compatibility with existing guests if soundhw is specified.
>>>
>>> - Switch to -machine pc-i440fx-1.6 only when xen_platform_pci=0 is
>>> specified and keep xenfv if xen_platform_pci=1. We still break
>>> compatibility when soundhw is specified together with xen_platform_pci=0.
>> - change the implementation of the soundhw option to use -device instead.
> Thanks, this sounds like the best option by far.
>
> I noticed that "-soundhw hda" becomes "-device intel-hda".
>
> Given that the VM config file exports a soundhw paramter, we would need
> a programmatic way to get the -device command line option from the
> soundhw paramter. Is there a way to do that?
Not only -device intel-hda, if I remember good there is also -device 
hda-duplex
soundhw now in libxl is only a string passed to qemu without check, 
probably is good add another parameter with a selectable options 
supported, similar to vga, for example audio=ac97|intelhda and libxl 
will check if exist and give to qemu the correct -device parameters.
The only problem is that audio device as many and not all qemu build 
support all (howevercurrently libxl does not care and isthe user having 
to make sure of the features support in qemu and view the log if qemu 
fails).
In addition there are also the disks to convert in -device.
I tried last year but with -device the automatic selection of bus and 
slot (unit now used in xen is not supported in -device if I remember 
good) was not working properly and the manual I did not know if I could 
do it working with cd/disk hot-plug working.

Thanks for any reply and sorry for my bad english.

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

[Ian Campbell]

On Fri, 2014-05-23 at 17:07 +0100, Stefano Stabellini wrote:
> 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.

Does 1.6 here refer to the qemu version? If so then I think we need to
consciously decide that we are happy for Xen 4.5 to depend on qemu >=
1.6 and document it in README.

qemu 1.6 was release in August 2013, which is ~10 months ago, it'll be
approximately a year old when we release. Are we happy with this from a
distro PoV?

I think it is likely that distros which have an older qemu (and users
of such distros) will be using the qemu which comes with Xen (and is
naturally new enough) rather than expecting to use the system qemu.

At some point we really ought to grow an option to let the user choose
the machine...

> 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

"graphics"

> 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

This takes me to "[Xen-devel] [v2][PATCH 4/8] xen, gfx passthrough:
reserve 00:02.0 for INTEL IGD" which I can't see the link to (including
via the 2 replies). Wrong link perhaps?

A Message-Id is generally a better identifier since I can feed it to the
archive of my choice and they aren't subject to e.g. future accidentally
renumberings etc.

> 
> 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");

FWIW you can use flexarray_append_pair which more naturally gathers an
option and its argument together (improving readability).

(personally I think the -machine should be pulled into both cases using
this method, but that's not a prereq for accepting the patch IMHO)

Other than that the patch itself seems sound (although I dislike code
motion mixed with real changes, I suppose this one is small enough that
I can cope).

Ian.

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

[Stefano Stabellini]

On Tue, 10 Jun 2014, Ian Campbell wrote:
> On Fri, 2014-05-23 at 17:07 +0100, Stefano Stabellini wrote:
> > 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.
> 
> Does 1.6 here refer to the qemu version?

Yes, every new QEMU version introduces a new PC machine version string.


> If so then I think we need to
> consciously decide that we are happy for Xen 4.5 to depend on qemu >=
> 1.6 and document it in README.
> 
> qemu 1.6 was release in August 2013, which is ~10 months ago, it'll be
> approximately a year old when we release. Are we happy with this from a
> distro PoV?
> 
> I think it is likely that distros which have an older qemu (and users
> of such distros) will be using the qemu which comes with Xen (and is
> naturally new enough) rather than expecting to use the system qemu.
> 
> At some point we really ought to grow an option to let the user choose
> the machine...

I think that the dependency on QEMU >= 1.6 is OK. The Xen PV Device went
in v1.6.0 and we certainy cannot go back to versions older than v1.5 due
to missing mapcache fixes. Fabio reported multiple times that QEMU 1.6
is the first stable version he tested.


> > 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
> 
> "graphics"
> 
> > 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
> 
> This takes me to "[Xen-devel] [v2][PATCH 4/8] xen, gfx passthrough:
> reserve 00:02.0 for INTEL IGD" which I can't see the link to (including
> via the 2 replies). Wrong link perhaps?
> 
> A Message-Id is generally a better identifier since I can feed it to the
> archive of my choice and they aren't subject to e.g. future accidentally
> renumberings etc.

1400237624-8505-5-git-send-email-tiejun.chen@intel.com


> > 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");
> 
> FWIW you can use flexarray_append_pair which more naturally gathers an
> option and its argument together (improving readability).
> 
> (personally I think the -machine should be pulled into both cases using
> this method, but that's not a prereq for accepting the patch IMHO)
> 
> Other than that the patch itself seems sound (although I dislike code
> motion mixed with real changes, I suppose this one is small enough that
> I can cope).
 
Should I go ahead with these minor changes and leave the soundhw problem
unsolved? I am not keen on fixing that.

1401803223.1582.5.camel@kazak.uk.xensource.com

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

[Ian Campbell]

On Wed, 2014-06-11 at 11:35 +0100, Stefano Stabellini wrote:
> On Tue, 10 Jun 2014, Ian Campbell wrote:
> > On Fri, 2014-05-23 at 17:07 +0100, Stefano Stabellini wrote:
> I think that the dependency on QEMU >= 1.6 is OK. The Xen PV Device went
> in v1.6.0 and we certainy cannot go back to versions older than v1.5 due
> to missing mapcache fixes. Fabio reported multiple times that QEMU 1.6
> is the first stable version he tested.

OK, then please can we update the README (and any other relevant docs)
as part of this change.

> > > 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
> > 
> > "graphics"
> > 
> > > 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
> > 
> > This takes me to "[Xen-devel] [v2][PATCH 4/8] xen, gfx passthrough:
> > reserve 00:02.0 for INTEL IGD" which I can't see the link to (including
> > via the 2 replies). Wrong link perhaps?
> > 
> > A Message-Id is generally a better identifier since I can feed it to the
> > archive of my choice and they aren't subject to e.g. future accidentally
> > renumberings etc.
> 
> 1400237624-8505-5-git-send-email-tiejun.chen@intel.com

(pedantic: the <>s are formally part of the message ID...)

OK, so I'm still not sure why this message is relevant to the sentence
which precedes the link.


> > > 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");
> > 
> > FWIW you can use flexarray_append_pair which more naturally gathers an
> > option and its argument together (improving readability).
> > 
> > (personally I think the -machine should be pulled into both cases using
> > this method, but that's not a prereq for accepting the patch IMHO)
> > 
> > Other than that the patch itself seems sound (although I dislike code
> > motion mixed with real changes, I suppose this one is small enough that
> > I can cope).
>  
> Should I go ahead with these minor changes

Please.

>  and leave the soundhw problem
> unsolved? I am not keen on fixing that.
> 
> 1401803223.1582.5.camel@kazak.uk.xensource.com

I came into this at the point where we were discussing how to support
using -device for soundhw, but I missed the bit where it was explained
why it was necessary to switch to that scheme.

If this change leads to regressions where existing cfg files no longer
work then we need to decide if that would be blocker for 4.5. I can't
see why it wouldn't be, but it's up to you and Konrad to agree I
suppose.

Ian.

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

[Fabio Fantoni]

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2014-06-11 12:44 GMT+02:00 Ian Campbell <Ian.Campbell@citrix.com>:

> On Wed, 2014-06-11 at 11:35 +0100, Stefano Stabellini wrote:
> > On Tue, 10 Jun 2014, Ian Campbell wrote:
> > > On Fri, 2014-05-23 at 17:07 +0100, Stefano Stabellini wrote:
> > I think that the dependency on QEMU >= 1.6 is OK. The Xen PV Device went
> > in v1.6.0 and we certainy cannot go back to versions older than v1.5 due
> > to missing mapcache fixes. Fabio reported multiple times that QEMU 1.6
> > is the first stable version he tested.
>
> OK, then please can we update the README (and any other relevant docs)
> as part of this change.
>

I tested upstream qemu from 1.2 and based on my test at least qemu 1.6.1 is
needed to be fairly complete and stable on xen (no major or critical bugs), I
started using it in production for a few month, in the next few days I will
start to put also qemu 2.0 on a production system.
I want to be remembered to specify >=1.6.1 because 1.6.0 have critical bug
that that prevents all hvm domUs start.


>
> > > > 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
> > >
> > > "graphics"
> > >
> > > > 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
> > >
> > > This takes me to "[Xen-devel] [v2][PATCH 4/8] xen, gfx passthrough:
> > > reserve 00:02.0 for INTEL IGD" which I can't see the link to (including
> > > via the 2 replies). Wrong link perhaps?
> > >
> > > A Message-Id is generally a better identifier since I can feed it to
> the
> > > archive of my choice and they aren't subject to e.g. future
> accidentally
> > > renumberings etc.
> >
> > 1400237624-8505-5-git-send-email-tiejun.chen@intel.com
>
> (pedantic: the <>s are formally part of the message ID...)
>
> OK, so I'm still not sure why this message is relevant to the sentence
> which precedes the link.
>
>
> > > > 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");
> > >
> > > FWIW you can use flexarray_append_pair which more naturally gathers an
> > > option and its argument together (improving readability).
> > >
> > > (personally I think the -machine should be pulled into both cases using
> > > this method, but that's not a prereq for accepting the patch IMHO)
> > >
> > > Other than that the patch itself seems sound (although I dislike code
> > > motion mixed with real changes, I suppose this one is small enough that
> > > I can cope).
> >
> > Should I go ahead with these minor changes
>
> Please.
>
> >  and leave the soundhw problem
> > unsolved? I am not keen on fixing that.
> >
> > 1401803223.1582.5.camel@kazak.uk.xensource.com
>
> I came into this at the point where we were discussing how to support
> using -device for soundhw, but I missed the bit where it was explained
> why it was necessary to switch to that scheme.
>
> If this change leads to regressions where existing cfg files no longer
> work then we need to decide if that would be blocker for 4.5. I can't
> see why it wouldn't be, but it's up to you and Konrad to agree I
> suppose.
>

I think add new option with audio device select and check similar to vga
would be good but I'm afraid I do not have time to do it recently.
May still be other cases in addition to the audio to cause problems if you
put xen-platform's pci slot fixed, I have not tested further.
Complete the conversion to -device does not seem blocker, FWIK would be
blocking the disks part conversion with q35 cipset but is not
currently supported
by xen.

Sorry for my bad english.


>
> Ian.
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
>

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