RE: [Xen-users] System seams slower with Xenified kernel and xend dies with SIG 15

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Gabriel Rossetti
> Sent: 02 August 2006 10:55
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] System seams slower with Xenified 
> kernel and xend dies with SIG 15
> 
> Ok, but wouldn't the OS take care of that? I don't think that 
> the driver
> does any
> address translations, it would make no sense, it would use virtual
> addresses and the OS, in my case a Xenified
> linux kernel, takes care of translations. I suspect that some of the
> changes made for Xen is the memory management, no?

Yes, but some of the changes in the Xenified kernel is to add/change the
code in drivers... And since the binary for the ATI (or nVidia) drivers
aren't source-code, they don't get the new code by recompiling the
kernel... 

> If so then I would make sense that it stays transparent so that
> everything would still work and
> not have to recompile everything like in Denali. At least 
> that's what I
> think, from what I saw in
> an OS class, and that I had to implement an OS's memory 
> managment, but I
> may be wrong. Also,
> my binary Intel ipw3945 wireless drivers work fine, so I don't think
> that is it, but then again, I may
> be wrong. From my light investigation I think it's a path problem, it
> can't find something apparently,
> and I don't get why not. I'll have to look at it more when I 
> find the time.

Maybe the wireless driver is more "well-behaved". 

--
Mats
> 
> Gabriel
> 
> 
> 
> Petersson, Mats wrote:
> >
> > Can't comment on xend dieing, but any binary driver would 
> be unlikely to
> > work in Xenified kernel, since the Xenified kernel changes 
> some of the
> > things that a driver needs to do when it translates memory addresses
> > from virtual to physical - there are now two different 
> types of physical
> > address: pseudo-physical, which is what the OS sees, and machine
> > physical, which is what the PROCESSOR sees. If you have a 
> Dom0 that has
> > 512MB of RAM, it will not necessarily have all it's memory from
> > 0..512MB, but it may actually be located anywhere Xen likes 
> it to be...
> > [Dom0 is most likely starting somewhere low, since it's 
> loaded early -
> > but that's just luck, rather than planned for]. Machine physical is
> > needed for the PCI (PCIe == PCIx == AGP == PCI in this case 
> - they are
> > just different hardware implementations of the same 
> protocol) so that
> > the card can access memory directly, and for sure all 
> modern graphics
> > cards have direct memory access capabilities (and most 
> likely doesn't do
> > much other than a standard 15 year old VGA card if you 
> don't use these
> > capability). 
> >
> >
> > --
> > Mats
> >
> >
> >   
> 
> 
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> 



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