Re: [Xen-devel] blkif_map error starting fourth guest domain

[Kieran Mansley <kmansley@xxxxxxxxxxxxxx>]

On Thu, 2007-06-07 at 16:12 +0100, Keir Fraser wrote:
> 
> 
> On 7/6/07 16:06, "Kieran Mansley" <kmansley@xxxxxxxxxxxxxx> wrote:
> 
> > The reason for blkif_map() failing seems to be the map_frontend_page()
> > call failing.
> > 
> > xm dmesg prints out:
> > (XEN) mm.c:2610:d0 Could not find L1 PTE for address e1204000
> > which seems likely to be connected to map_frontend_page() failing.
> 
> Yes, this is the problem. You'll need to add some more tracing, find out
> exactly which grant_map operation issued by dom0 is failing, and find out
> why Xen thinks there is no pte mapping the specified virtual address.

The grant map that's failing is (linux-2.6-xen-
sparse/drivers/xen/blkback/interface.c:62):

        gnttab_set_map_op(&op, (unsigned long)blkif->blk_ring_area->addr,
                          GNTMAP_host_map, shared_page, blkif->domid);

        if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
                BUG();

I'll get some more tracing and info about why this page supplied by the
frontend doesn't have a PTE when I get some spare time.

Kieran


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