Re: [Xen-devel] 3GB memory restriction for pv domU with PCI

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

> sticking points are this and the 2MB contig alloc for the tachyon 2 MB
> block for the FC SEST. I feel like if we don't get pvops in now, it'll
> be a hard sell later on.

The 2MB contig alloc ought to work with the pci_alloc_coherent function.

> 
> Anyway, thanks for the info and I'll keep my fingers crossed that 5
> days is all it takes.
> 
> >
> > If this is a show-stopper right now, you could come with a hack where
> > the resource check is just ignored.
> >
> I assume one could do this only if not using PCI passthrough?

Well, it is basically relaxing the criteria. In the olden days (2.6.18)
the System RAM region wa not accounted for. Nowadays it is. So when
a PCI device requests a region that the kernel thinks is System RAM
it tells it to buzz of. In 2.6.18, the kernel would have no trouble
giving you that region. So the hack is just to relax the criteria
and maybe just do:

 if (strncmp(r->name,"System RAM") == 0) {
        return OK;
 }

Or something like that in the resource.c file. I do't remember the
details of that file, but that looked like one of those quick-and-fast
ways of doing this. The right way is to actually make the guest aware of the
PCI hole the Dom0 has and just shift the memory as required. It sounds
easy :-)

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel