Re: call for testing: mfi(4)

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

On Mon, Apr 21, 2008 at 02:50:22PM -0400, Brian A. Seklecki wrote:
> [...]
> 
> At 128MB for the Dom0, the pmap problem with mfi(4) is gone, but now
> manifests itself in bnx(4), 192MB seems to be a good consensus.
> 
> See attached for panic @ 128MB Dom0
> 
> ~BAS
> 
> P.S. Maybe I'm greedy, but I would think that the Xen kernel + NetBSD
> DOM0 + MFS could use ~128MB or less in a Veso-like deployment,
> maximizing physical RAM available to DomUs.  Dom0 existing to manage
> iSCSI targets, provide VLAN bridging, environmental data, and RAID
> monitoring optionally (just musing)

I suspect the DMA buffers for mfi and bge take quite a bit of RAM.
I suspect the issue here is the way the kernel exanges pages with Xen to
get DMA-safe memory (below the 4GB limit). Xen allocates RAM top-down,
and it's likely the domain0 initial RAM is all above 4GB.

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