Re: [Xen-devel] Network drop to domU (netfront: rx->offset: 0, size: 4294967295)

["PCextreme B.V. - Wido den Hollander" <wido@xxxxxxxxxxxx>]

Hi Keir,

> The issue is that dom0 is trying to copy data to a domU-provided buffer, but
> the buffer details appear bogus. Netback returns a -1 error to netfront,
> which then prints out its error message. It's not immediately obvious
> whether the bug is in netfront or netback. If it's an issue that crops up
> with many guests then I suppose it's more likely a netback issue, which is a
> pain. Do domUs lose their connection at the same time, or is it random
> individual domUs losing their connection from time to time?

I am running some tests at the moment to verify wether this is a random
issue or a "global" issue.

So far i think it is random to just some individual domU's. But i will
keep running some tests.

> If it's an issue that crops up with many guests then I suppose it's
more likely a netback issue, which is a pain.

I already assumed this would be a pain, any way to determine if it is a
netback issue? Adding some verbose messages to the kernel?

-  
Met vriendelijke groet,

Wido den Hollander
Hoofd Systeembeheer / CSO
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On Wed, 2009-05-20 at 05:43 -0700, Keir Fraser wrote:
> On 20/05/2009 03:52, "PCextreme B.V. - Wido den Hollander"
> <wido@xxxxxxxxxxxx> wrote:
> 
> > I took the kernel source and started looking where the netfront messages
> > was being printed and it seemed some kind of memory allocation issue? I
> > have found some old messages with patches but those did not apply to my
> > current source.
> 
> The issue is that dom0 is trying to copy data to a domU-provided buffer, but
> the buffer details appear bogus. Netback returns a -1 error to netfront,
> which then prints out its error message. It's not immediately obvious
> whether the bug is in netfront or netback. If it's an issue that crops up
> with many guests then I suppose it's more likely a netback issue, which is a
> pain. Do domUs lose their connection at the same time, or is it random
> individual domUs losing their connection from time to time?
> 
>  -- Keir
> 
> > Since this is a running production system i can schedule a reboot for a
> > new kernel, but this takes some time.
> 
>

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