Xen users - Jun 2012 - Which QEMU device-model to use for Windows HVM guests???

Just wondering about which QEMU version to use. Looking in the xl.cfg 
MAN page, you can choose from "qemu-xen-traditional" or 
"qemu-xen",
however i have seen a third one "qemu-dm" WHICH is not listed in the 
xl.cfg man page.

I know the "qemu-xen-traditional" device-model is the default one as
it
is more stable, compatible and so forth. The "qemu-xen" is the qemu 
upstream one and i am sure still not so stable without tweaking, BUT 
have read that f you want to use IOMMU (pci passthrough), than 
"qemu-xen" doesn''t have support or is buggy, or something
like that. I
do want to use PCI passthrough so i guess that is not an option. 
HOWEVER, i have read people use "qemu-dm" and don''t know how
different
is that compared to the other two choices.

SO, considering creating a VM to be of type HVM, such as any flavor of 
Windows, which qemu device-model would give the best results using Xen 
4.2-unstable??

On Wed, 2012-06-13 at 14:24 +0100, cyberhawk001@gmail.com
wrote:
> Just wondering about which QEMU version to use. Looking in the xl.cfg 
> MAN page, you can choose from "qemu-xen-traditional" or 
"qemu-xen",
> however i have seen a third one "qemu-dm" WHICH is not listed in
the
> xl.cfg man page.
> 
> I know the "qemu-xen-traditional" device-model is the default one
as it
> is more stable, compatible and so forth. The "qemu-xen" is the
qemu
> upstream one and i am sure still not so stable without tweaking, BUT 
> have read that f you want to use IOMMU (pci passthrough), than 
> "qemu-xen" doesn''t have support or is buggy, or
something like that. I
> do want to use PCI passthrough so i guess that is not an option. 
> HOWEVER, i have read people use "qemu-dm" and don''t know
how different
> is that compared to the other two choices.
qemu-dm is just an umbrella term for the device model, it''s not a
specific version.
> SO, considering creating a VM to be of type HVM, such as any flavor of 
> Windows, which qemu device-model would give the best results using Xen 
> 4.2-unstable??
Use the default, which is qemu-xen-traditional.

Ian.

(adding the list back to the CC)

On Wed, 2012-06-13 at 14:43 +0100, cyberhawk001@gmail.com
wrote:
> On 6/13/2012 9:31 AM, Ian Campbell wrote: 
> > On Wed, 2012-06-13 at 14:24 +0100, cyberhawk001@gmail.com wrote:
> > > Just wondering about which QEMU version to use. Looking in the
xl.cfg
> > > MAN page, you can choose from "qemu-xen-traditional" or
"qemu-xen",
> > > however i have seen a third one "qemu-dm" WHICH is not
listed in the
> > > xl.cfg man page.
> > > 
> > > I know the "qemu-xen-traditional" device-model is the
default one as it
> > > is more stable, compatible and so forth. The "qemu-xen"
is the qemu
> > > upstream one and i am sure still not so stable without tweaking,
BUT
> > > have read that f you want to use IOMMU (pci passthrough), than 
> > > "qemu-xen" doesn''t have support or is buggy,
or something like that. I
> > > do want to use PCI passthrough so i guess that is not an option. 
> > > HOWEVER, i have read people use "qemu-dm" and
don''t know how different
> > > is that compared to the other two choices.
> > qemu-dm is just an umbrella term for the device model, it''s
not a
> > specific version.
> 
> AHH OK i see. SO the qemu-dm is an umbrella term for what? If you
> specify that in the VM config file, what does Xen load? 
You can''t specify it in the config file, it''s just a word we
use when we
mean either qemu-xen or qemu-xen-traditional. It''s not a valid actual
value.
> I was curious since i saw this line in a VM config file somewhere:
> 
> device_model = "/usr/lib64/xen/bin/qemu-dm"
This is the path to the dm binary to use, you should never need to
specify this (any more, this wasn''t true in 4.1 and xend)

"/usr/lib64/xen/bin/qemu-dm" happens to be the binary for
qemu-xen-traditional.

Ian.

I know, i know, sorry my mistake, I was replying too fast and hit the 
wrong reply button... :)

OK well thanks Ian, than answers that question... i appreciate it as always.



On 6/13/2012 9:58 AM, Ian Campbell wrote:
> (adding the list back to the CC)
>
> On Wed, 2012-06-13 at 14:43 +0100, cyberhawk001@gmail.com wrote:
>> On 6/13/2012 9:31 AM, Ian Campbell wrote:
>>> On Wed, 2012-06-13 at 14:24 +0100, cyberhawk001@gmail.com wrote:
>>>> Just wondering about which QEMU version to use. Looking in the
xl.cfg
>>>> MAN page, you can choose from "qemu-xen-traditional"
or  "qemu-xen",
>>>> however i have seen a third one "qemu-dm" WHICH is
not listed in the
>>>> xl.cfg man page.
>>>>
>>>> I know the "qemu-xen-traditional" device-model is the
default one as it
>>>> is more stable, compatible and so forth. The
"qemu-xen" is the qemu
>>>> upstream one and i am sure still not so stable without
tweaking, BUT
>>>> have read that f you want to use IOMMU (pci passthrough), than
>>>> "qemu-xen" doesn''t have support or is buggy,
or something like that. I
>>>> do want to use PCI passthrough so i guess that is not an
option.
>>>> HOWEVER, i have read people use "qemu-dm" and
don''t know how different
>>>> is that compared to the other two choices.
>>> qemu-dm is just an umbrella term for the device model,
it''s not a
>>> specific version.
>> AHH OK i see. SO the qemu-dm is an umbrella term for what? If you
>> specify that in the VM config file, what does Xen load?
> You can''t specify it in the config file, it''s just a word
we use when we
> mean either qemu-xen or qemu-xen-traditional. It''s not a valid
actual
> value.
>
>> I was curious since i saw this line in a VM config file somewhere:
>>
>> device_model = "/usr/lib64/xen/bin/qemu-dm"
> This is the path to the dm binary to use, you should never need to
> specify this (any more, this wasn''t true in 4.1 and xend)
>
> "/usr/lib64/xen/bin/qemu-dm" happens to be the binary for
> qemu-xen-traditional.
>
> Ian.
>
>
>