Re: Running PV kernel on XenServer kills all VMs

[Stephen Borrill <netbsd%precedence.co.uk@localhost>]

On Fri, 11 Jun 2010, Stephen Borrill wrote:
> I've finally worked out how to get NetBSD i386 and amd64 mostly running in 
> full PV mode rather than HVM within Citrix XenServer. I say mostly running 
> because the downside is that booting the VM kills networking for all other 
> VMs and even stops them being able to shutdown cleanly leading to a forced 
> reboot of the XenServer.
>
> dmesg on the dom0 shows:
>
> __ratelimit: 1431411 callbacks suppressed
> xen_net: Memory squeeze in netback driver.
> xen_net: Memory squeeze in netback driver.
> xen_net: Memory squeeze in netback driver.
>
> Google suggests that raising (or hardwiring) dom0_mem may help, but other 
> guests don't appear to need this and it's already set to 752M.

I spoke to Citrix about this problem. They said:

"These messages can only occur with a network front end which uses
"flipping" mode for RX traffic. We currently do not support (and
therefore do not test) any guests which use this mode and it looks like
it has repressed.

Someone needs to port the BSD frontend to use "copying" mode for its RX
traffic. Flipping mode may well disappear in a future release."

Comments?

--
Stephen