Question on RHEL 6 support

Question on RHEL 6 support

[Alok Sinha]

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Hi,

   I am trying to run RHEL 6 as guest over XEN (RHEL 5.6 as host) hypervisor.
   It seems that RHEL 6 loads the paravirt drivers by default and thus HVM mode is not working.

   Any idea on this?

   I saw somewhere that including xen_emul_unplug=never will help. Is there any other way it can be avoided?

-Alok

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Re: Question on RHEL 6 support

[Pasi Kärkkäinen]

On Thu, Oct 20, 2011 at 04:18:07PM +0530, Alok Sinha wrote:
>    Hi,

Hello,

>       I am trying to run RHEL 6 as guest over XEN (RHEL 5.6 as host)
>    hypervisor.
>       It seems that RHEL 6 loads the paravirt drivers by default and thus HVM
>    mode is not working.
>       Any idea on this?

What do you mean with "HVM mode is not working" ?

PVHVM drivers (for HVM guests) are there to make disk/net performance a LOT better!
The default qemu-dm emulated ide controller and realtek nic are not very efficient..

>       I saw somewhere that including xen_emul_unplug=never will help. Is
>    there any other way it can be avoided?
>

You can also disable the xen platform pci device for that VM from dom0, 
then the VM will not activate PVHVM drivers.

-- Pasi

Re: Question on RHEL 6 support

[Alok Sinha]

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Sent from my iPhone

On 20-Oct-2011, at 7:32 PM, "Pasi Kärkkäinen" <pasik@iki.fi> wrote:

> On Thu, Oct 20, 2011 at 04:18:07PM +0530, Alok Sinha wrote:
>>   Hi,
> 
> Hello,
> 
>>      I am trying to run RHEL 6 as guest over XEN (RHEL 5.6 as host)
>>   hypervisor.
>>      It seems that RHEL 6 loads the paravirt drivers by default and thus HVM
>>   mode is not working.
>>      Any idea on this?
> 
> What do you mean with "HVM mode is not working" ?
> 
> PVHVM drivers (for HVM guests) are there to make disk/net performance a LOT better!
> The default qemu-dm emulated ide controller and realtek nic are not very efficient..
> 
>>      I saw somewhere that including xen_emul_unplug=never will help. Is
>>   there any other way it can be avoided?
>> 
> 
> You can also disable the xen platform pci device for that VM from dom0, 
> then the VM will not activate PVHVM drivers.
> 
> -- 

How? Is there cli/API?
Alok

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Re: Question on RHEL 6 support

[Alok Sinha]

Pasi,

   Thanks for your response.
   So how do I disable xen platform device for VM? Any pointers?
-Alok

On Oct 20, 2011, at 7:30 PM, Pasi Kärkkäinen wrote:

> On Thu, Oct 20, 2011 at 04:18:07PM +0530, Alok Sinha wrote:
>>   Hi,
> 
> Hello,
> 
>>      I am trying to run RHEL 6 as guest over XEN (RHEL 5.6 as host)
>>   hypervisor.
>>      It seems that RHEL 6 loads the paravirt drivers by default and thus HVM
>>   mode is not working.
>>      Any idea on this?
> 
> What do you mean with "HVM mode is not working" ?
> 
> PVHVM drivers (for HVM guests) are there to make disk/net performance a LOT better!
> The default qemu-dm emulated ide controller and realtek nic are not very efficient..
> 
>>      I saw somewhere that including xen_emul_unplug=never will help. Is
>>   there any other way it can be avoided?
>> 
> 
> You can also disable the xen platform pci device for that VM from dom0, 
> then the VM will not activate PVHVM drivers.
> 
> -- Pasi
> 

Re: Question on RHEL 6 support

[Pasi Kärkkäinen]

On Fri, Oct 21, 2011 at 10:29:46AM +0530, Alok Sinha wrote:
> Pasi,
> 
>    Thanks for your response.
>    So how do I disable xen platform device for VM? Any pointers?
>

You should be able to change it from /etc/xen/<name_of_the_vm> configfile.

Try:
xen_platform_pci=0

-- Pasi

> 
> On Oct 20, 2011, at 7:30 PM, Pasi Kärkkäinen wrote:
> 
> > On Thu, Oct 20, 2011 at 04:18:07PM +0530, Alok Sinha wrote:
> >>   Hi,
> > 
> > Hello,
> > 
> >>      I am trying to run RHEL 6 as guest over XEN (RHEL 5.6 as host)
> >>   hypervisor.
> >>      It seems that RHEL 6 loads the paravirt drivers by default and thus HVM
> >>   mode is not working.
> >>      Any idea on this?
> > 
> > What do you mean with "HVM mode is not working" ?
> > 
> > PVHVM drivers (for HVM guests) are there to make disk/net performance a LOT better!
> > The default qemu-dm emulated ide controller and realtek nic are not very efficient..
> > 
> >>      I saw somewhere that including xen_emul_unplug=never will help. Is
> >>   there any other way it can be avoided?
> >> 
> > 
> > You can also disable the xen platform pci device for that VM from dom0, 
> > then the VM will not activate PVHVM drivers.
> > 
> > -- Pasi
> > 
> 

Re: Question on RHEL 6 support

[Alok Sinha]

Thanks Pasi. I am trying that.

By the way, I am getting following error while creating a HVM with rhel as guest:


"ERROR: no interface found for primary=eth0"


-Alok



On Oct 21, 2011, at 11:41 AM, Pasi Kärkkäinen wrote:

> On Fri, Oct 21, 2011 at 10:29:46AM +0530, Alok Sinha wrote:
>> Pasi,
>> 
>>   Thanks for your response.
>>   So how do I disable xen platform device for VM? Any pointers?
>> 
> 
> You should be able to change it from /etc/xen/<name_of_the_vm> configfile.
> 
> Try:
> xen_platform_pci=0
> 
> -- Pasi
> 
>> 
>> On Oct 20, 2011, at 7:30 PM, Pasi Kärkkäinen wrote:
>> 
>>> On Thu, Oct 20, 2011 at 04:18:07PM +0530, Alok Sinha wrote:
>>>>  Hi,
>>> 
>>> Hello,
>>> 
>>>>     I am trying to run RHEL 6 as guest over XEN (RHEL 5.6 as host)
>>>>  hypervisor.
>>>>     It seems that RHEL 6 loads the paravirt drivers by default and thus HVM
>>>>  mode is not working.
>>>>     Any idea on this?
>>> 
>>> What do you mean with "HVM mode is not working" ?
>>> 
>>> PVHVM drivers (for HVM guests) are there to make disk/net performance a LOT better!
>>> The default qemu-dm emulated ide controller and realtek nic are not very efficient..
>>> 
>>>>     I saw somewhere that including xen_emul_unplug=never will help. Is
>>>>  there any other way it can be avoided?
>>>> 
>>> 
>>> You can also disable the xen platform pci device for that VM from dom0, 
>>> then the VM will not activate PVHVM drivers.
>>> 
>>> -- Pasi
>>> 
>> 

Re: Question on RHEL 6 support

[Pasi Kärkkäinen]

On Fri, Oct 21, 2011 at 02:41:36PM +0530, Alok Sinha wrote:
> Thanks Pasi. I am trying that.
> 
> By the way, I am getting following error while creating a HVM with rhel as guest:
> 
> 
> "ERROR: no interface found for primary=eth0"
> 

Where do you get that error? on dom0? in domU ? When does that happen?

-- Pasi


> 
> 
> 
> On Oct 21, 2011, at 11:41 AM, Pasi Kärkkäinen wrote:
> 
> > On Fri, Oct 21, 2011 at 10:29:46AM +0530, Alok Sinha wrote:
> >> Pasi,
> >> 
> >>   Thanks for your response.
> >>   So how do I disable xen platform device for VM? Any pointers?
> >> 
> > 
> > You should be able to change it from /etc/xen/<name_of_the_vm> configfile.
> > 
> > Try:
> > xen_platform_pci=0
> > 
> > -- Pasi
> > 
> >> 
> >> On Oct 20, 2011, at 7:30 PM, Pasi Kärkkäinen wrote:
> >> 
> >>> On Thu, Oct 20, 2011 at 04:18:07PM +0530, Alok Sinha wrote:
> >>>>  Hi,
> >>> 
> >>> Hello,
> >>> 
> >>>>     I am trying to run RHEL 6 as guest over XEN (RHEL 5.6 as host)
> >>>>  hypervisor.
> >>>>     It seems that RHEL 6 loads the paravirt drivers by default and thus HVM
> >>>>  mode is not working.
> >>>>     Any idea on this?
> >>> 
> >>> What do you mean with "HVM mode is not working" ?
> >>> 
> >>> PVHVM drivers (for HVM guests) are there to make disk/net performance a LOT better!
> >>> The default qemu-dm emulated ide controller and realtek nic are not very efficient..
> >>> 
> >>>>     I saw somewhere that including xen_emul_unplug=never will help. Is
> >>>>  there any other way it can be avoided?
> >>>> 
> >>> 
> >>> You can also disable the xen platform pci device for that VM from dom0, 
> >>> then the VM will not activate PVHVM drivers.
> >>> 
> >>> -- Pasi
> >>> 
> >> 
> 

Re: Question on RHEL 6 support

[Alok Sinha]

This happens when I am creating the VM. This leaves the VM imaging incomplete,

-Alok


On Oct 21, 2011, at 4:04 PM, Pasi Kärkkäinen wrote:

> On Fri, Oct 21, 2011 at 02:41:36PM +0530, Alok Sinha wrote:
>> Thanks Pasi. I am trying that.
>> 
>> By the way, I am getting following error while creating a HVM with rhel as guest:
>> 
>> 
>> "ERROR: no interface found for primary=eth0"
>> 
> 
> Where do you get that error? on dom0? in domU ? When does that happen?
> 
> -- Pasi
> 
> 
>> 
>> 
>> 
>> On Oct 21, 2011, at 11:41 AM, Pasi Kärkkäinen wrote:
>> 
>>> On Fri, Oct 21, 2011 at 10:29:46AM +0530, Alok Sinha wrote:
>>>> Pasi,
>>>> 
>>>>  Thanks for your response.
>>>>  So how do I disable xen platform device for VM? Any pointers?
>>>> 
>>> 
>>> You should be able to change it from /etc/xen/<name_of_the_vm> configfile.
>>> 
>>> Try:
>>> xen_platform_pci=0
>>> 
>>> -- Pasi
>>> 
>>>> 
>>>> On Oct 20, 2011, at 7:30 PM, Pasi Kärkkäinen wrote:
>>>> 
>>>>> On Thu, Oct 20, 2011 at 04:18:07PM +0530, Alok Sinha wrote:
>>>>>> Hi,
>>>>> 
>>>>> Hello,
>>>>> 
>>>>>>    I am trying to run RHEL 6 as guest over XEN (RHEL 5.6 as host)
>>>>>> hypervisor.
>>>>>>    It seems that RHEL 6 loads the paravirt drivers by default and thus HVM
>>>>>> mode is not working.
>>>>>>    Any idea on this?
>>>>> 
>>>>> What do you mean with "HVM mode is not working" ?
>>>>> 
>>>>> PVHVM drivers (for HVM guests) are there to make disk/net performance a LOT better!
>>>>> The default qemu-dm emulated ide controller and realtek nic are not very efficient..
>>>>> 
>>>>>>    I saw somewhere that including xen_emul_unplug=never will help. Is
>>>>>> there any other way it can be avoided?
>>>>>> 
>>>>> 
>>>>> You can also disable the xen platform pci device for that VM from dom0, 
>>>>> then the VM will not activate PVHVM drivers.
>>>>> 
>>>>> -- Pasi
>>>>> 
>>>> 
>> 

Re: Question on RHEL 6 support

[Paolo Bonzini]

On 10/21/2011 08:11 AM, Pasi Kärkkäinen wrote:
>> >
>> >      Thanks for your response.
>> >      So how do I disable xen platform device for VM? Any pointers?
>> >
> You should be able to change it from/etc/xen/<name_of_the_vm>  configfile.
>
> Try:
> xen_platform_pci=0

That doesn't exist.

Paolo

Re: Question on RHEL 6 support

[Alok Sinha]

Hmm...any other alternatives?

-Alok


On Oct 21, 2011, at 6:54 PM, Paolo Bonzini wrote:

> On 10/21/2011 08:11 AM, Pasi Kärkkäinen wrote:
>>>> 
>>>>     Thanks for your response.
>>>>     So how do I disable xen platform device for VM? Any pointers?
>>>> 
>> You should be able to change it from/etc/xen/<name_of_the_vm>  configfile.
>> 
>> Try:
>> xen_platform_pci=0
> 
> That doesn't exist.
> 
> Paolo

Re: Question on RHEL 6 support

[Paolo Bonzini]

On 10/21/2011 03:40 PM, Alok Sinha wrote:
> Hmm...any other alternatives?

Hard to see without dmesg output or something like that.  It's simpler 
if you open a support ticket or BZ with Red Hat, since the Xen version 
in RHEL is quite old.

Paolo

Re: Question on RHEL 6 support

[Alok Sinha]

We have XEN 3.4.3 loaded, is that old?
Does RHEL 6 has compatibility issue with XEN 3? Does it need XEN 4?

-Alok

On Oct 21, 2011, at 7:13 PM, Paolo Bonzini wrote:

> On 10/21/2011 03:40 PM, Alok Sinha wrote:
>> Hmm...any other alternatives?
> 
> Hard to see without dmesg output or something like that.  It's simpler 
> if you open a support ticket or BZ with Red Hat, since the Xen version 
> in RHEL is quite old.
> 
> Paolo

Re: Question on RHEL 6 support

[Paolo Bonzini]

On 10/21/2011 03:50 PM, Alok Sinha wrote:
> We have XEN 3.4.3 loaded, is that old?

Ah ok, I understood you were using RHEL5's own Xen.  As I said, if you 
open a BZ you can upload your configuration and serial console output 
there.  Without those it's not worth guessing.

> Does RHEL 6 has compatibility issue with XEN 3? Does it need XEN 4?

It runs on RHEL5's own Xen, which is 3.1.2 -- with a lot of patches, but 
none particularly targeted to RHEL6.  If your hypervisor had problems 
with RHEL6 it would not go past GRUB at all, I think.

Paolo

Re: Question on RHEL 6 support

[Pasi Kärkkäinen]

On Fri, Oct 21, 2011 at 03:24:29PM +0200, Paolo Bonzini wrote:
> On 10/21/2011 08:11 AM, Pasi Kärkkäinen wrote:
>>> >
>>> >      Thanks for your response.
>>> >      So how do I disable xen platform device for VM? Any pointers?
>>> >
>> You should be able to change it from/etc/xen/<name_of_the_vm>  configfile.
>>
>> Try:
>> xen_platform_pci=0
>
> That doesn't exist.
>

Hmm, or is it:
xen_platform_device=0

Anyway there definitely is a configuration option for controlling the xen platform pci device,
which can enable or disable PVHVM drivers.

I can't just remember which one the option is called.. 
(and I can't grep the sources right now.. travelling.)

-- Pasi

Re: Question on RHEL 6 support

[Paolo Bonzini]

On 10/21/2011 04:14 PM, Pasi Kärkkäinen wrote:
>>> >>  Try:
>>> >>  xen_platform_pci=0
>> >
>> >  That doesn't exist.
>> >
> Hmm, or is it:
> xen_platform_device=0
>
> Anyway there definitely is a configuration option for controlling the xen platform pci device,
> which can enable or disable PVHVM drivers.
>
> I can't just remember which one the option is called..
> (and I can't grep the sources right now.. travelling.)

It's xen_platform_pci, but it doesn't exist on either RHEL5 Xen or 3.4.

Paolo