Re: Netbsd XEN nothing I can boot in

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

On Thu, Sep 14, 2006 at 03:27:44PM +1200, Ivan Vari wrote:
> Helpful users of ports-xen!
> 
> >Hum, just a though. Could you try reducing the amount of RAM below 2G ?
> >mem=2047M to xen boot options should be enough.
> 
> Yes with this memory parameter I can start NetBSD install on my DL380. 
> In fact the install starts with mem=3095M too but not above that. THANKS 
> for everybody!
> 
> But I have another question since NetBSD kernels are sensitive about the 
> memory settings.

I'm not sure it's NetBSD, or if it's an issue with the way this box reports
its memory and Xen. The NetBSD kernel trusts what Xen tells him about useable
memory.

With a 32bit non-PAE system you can't have much more than 3GB physical memory
anyway, because in the 4GB physical address space you have to put all what's
memory-mapped: RAM, BIOS roms, PCI memory-mapped space, etc ...
usually all of this needs about 1GB, so out of the 4GB RAM one part of it
(1GB) is mapped above 4GB and can't be accessed by 32bit systems.

> Losing that 1GB is crucial for me because the machine I 
> am planning to split with NetBSD VMs has 2 heavily used services: 
> squid+mailserver with mimedefang. The mailserver itself would need 2GB 
> of ram and the rest could go for the squid VM, socks VM, VPN VM. Without 
> that 1GB it's very tight.
> 
> Is it safe to ran this memory hungry sendmail+mimedefang inside of VM? I 
> am just concerned about how stable that VM would be... Virtualization is 
> not an option for every machine/service perhaps it's one of those?

This should not be a problem.

-- 
Manuel Bouyer, LIP6, Universite Paris VI.           
Manuel.Bouyer%lip6.fr@localhost
     NetBSD: 26 ans d'experience feront toujours la difference
--