Re: xen and networking problems

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Fri, Nov 06, 2009 at 02:53:03PM -0700, Brook Milligan wrote:
> Manuel Bouyer writes:
>  > How much RAM does you machine have ? If this systeme supports it it would 
> also
>  > be usefull to test amd64.
> 
> I have tested the machine with 4GB, 8GB and 16GB RAM.  The problems
> all occur whenever there is more than 4GB of RAM.  Networking works in
> all the various xen/kernel combinations with only 4GB.  


OK, so as I understant it, fxp works with a PAE kernel too, but only
if there's 4GB or less RAM in the system ?

If so then it's probably an issue with bus_dma(9) not being used
properly.

> Clearly, the combination of PAE support and >4GB memory triggers the
> problems.  Does this mean that xen is not really supporting PAE or
> that the hardware is not really correct or that there is some specific
> interaction with the network interface or ... ?  How can any of this
> be tested?  In all cases everything about the machine seems to work,
> except for the network interface when PAE support is involved and
> there is >4GB RAM.

As it's i386-only, a non-PAE kernel will never use ram above 4GB. So
it's not PAE ws non-PAE, it's really the 4Gb limit that triggers the
issue.

The bus_dma(9) usage in fxp needs to be audited. I've tested i386PAE on
a system with 8GB RAM and various devices, without problems. Unfortunably
I don't have a add-on fxp to test.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--