strange problem with virtio on guest with over 3648M RAM

strange problem with virtio on guest with over 3648M RAM

[Henrik Holst]

Hello KVM developers!

We are experiencing a very strange problem: we have been testing Ubuntu 
Hardy Heron Server as a guest (kvm-68 on the host) and when using the 
virtio nic everything works fine until we give the guest more than 3648 
MiB of RAM.

If we for example start with "-m 4096" then the ubuntu guest brings up 
eth0 but it is impossible to get a dhcp address and if one sets a static 
address no packets what so ever is leaving the guest.

So there seam to be a problem with the virtio guest drivers when there 
is more than 3648 MiB of ram available :), is there anyone else that 
have experienced the same problems or are there people running virtio on 
guest with more ram where everything is working ok?

This problem could be local to ubuntu but I don't know of any other 
distribution with virtio guest drivers out of the box.

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Re: strange problem with virtio on guest with over 3648M RAM

[Henrik Holst]

Henrik Holst skrev:
> Hello KVM developers!
>
> We are experiencing a very strange problem: we have been testing 
> Ubuntu Hardy Heron Server as a guest (kvm-68 on the host) and when 
> using the virtio nic everything works fine until we give the guest 
> more than 3648 MiB of RAM.
>
> If we for example start with "-m 4096" then the ubuntu guest brings up 
> eth0 but it is impossible to get a dhcp address and if one sets a 
> static address no packets what so ever is leaving the guest.
>
> So there seam to be a problem with the virtio guest drivers when there 
> is more than 3648 MiB of ram available :), is there anyone else that 
> have experienced the same problems or are there people running virtio 
> on guest with more ram where everything is working ok?
>
> This problem could be local to ubuntu but I don't know of any other 
> distribution with virtio guest drivers out of the box.

Forgot to mention that the e1000 guest drivers works perfectly fine 
regardless of the amount of ram on the guest.

/Henrik Holst

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Re: strange problem with virtio on guest with over 3648M RAM

[Anthony Liguori]

Henrik Holst wrote:
> Hello KVM developers!
>
> We are experiencing a very strange problem: we have been testing Ubuntu 
> Hardy Heron Server as a guest (kvm-68 on the host) and when using the 
> virtio nic everything works fine until we give the guest more than 3648 
> MiB of RAM.
>
> If we for example start with "-m 4096" then the ubuntu guest brings up 
> eth0 but it is impossible to get a dhcp address and if one sets a static 
> address no packets what so ever is leaving the guest.
>
> So there seam to be a problem with the virtio guest drivers when there 
> is more than 3648 MiB of ram available :), is there anyone else that 
> have experienced the same problems or are there people running virtio on 
> guest with more ram where everything is working ok?
>   

It's a know bug.  I have a fix for it locally that I'll send out today.

Regards,

Anthony Liguori

> This problem could be local to ubuntu but I don't know of any other 
> distribution with virtio guest drivers out of the box.
>
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> This SF.net email is sponsored by the 2008 JavaOne(SM) Conference 
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>   


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Re: strange problem with virtio on guest with over 3648M RAM

[Henrik Holst]

Anthony Liguori wrote:
> Henrik Holst wrote:
>> Hello KVM developers!
>>
>> We are experiencing a very strange problem: we have been testing 
>> Ubuntu Hardy Heron Server as a guest (kvm-68 on the host) and when 
>> using the virtio nic everything works fine until we give the guest 
>> more than 3648 MiB of RAM.
>>
>> If we for example start with "-m 4096" then the ubuntu guest brings 
>> up eth0 but it is impossible to get a dhcp address and if one sets a 
>> static address no packets what so ever is leaving the guest.
>>
>> So there seam to be a problem with the virtio guest drivers when 
>> there is more than 3648 MiB of ram available :), is there anyone else 
>> that have experienced the same problems or are there people running 
>> virtio on guest with more ram where everything is working ok?
>>   
>
> It's a know bug.  I have a fix for it locally that I'll send out today.
>
> Regards,
>
> Anthony Liguori
Many thanks Anthony!

/Henrik Holst


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