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

[Gabriel Rossetti <rossettigab@xxxxxxxxxxx>]

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?
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.

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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