This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] Nouveau on dom0

On Thu, Mar 04, 2010 at 02:47:58PM +0530, Arvind R wrote:
> On Wed, Mar 3, 2010 at 11:43 PM, Konrad Rzeszutek Wilk
> <konrad.wilk@xxxxxxxxxx> wrote:
> >> > aio-write -
> >>
> >> which triggers do_page_fault, handle_mm_fault, do_linear_fault, __do_fault
> >> and finally ttm_bo_vm_fault.
> > I've attached a simple patch I wrote some time ago to get the real MFNs
> > and its page protection. I think you can adapt it (print_data function to 
> > be exact)
> > to peet at the PTE and its protection values.
> Have patched - did not apply clean. Will compile and get some info.

Right. I don't think it would help you immediately - I was thinking you could
take the print_data function and just jam it in the tt_bo_vm_fault code
and use it to print the PTE data.
> > There is an extra flag that the PTE can have when running under Xen: 
> > This signifies that the PFN is actually the MFN. In this case thought
> > it sholdn't be enabled b/c the memory is actually gathered from
> > alloc_page. But if it is, it might be the culprit.
> >> What can possibly cause the fault-handler to repeat endlessly?
> FYI: about 2000 times a second - slowed by printk
> >> If a wrong page is backed at the user-address, it should create bad_access 
> >> or
> >> some other subsequent events - but the system is running fine minus all 
> >> local
> > So  you see this fault handler being called endlessly while the machine
> > is still running and other pieces of code work just fine, right?
> Right. Can ssh in - but no local console
> >> ttm_tt_get_page calls alloc in a loop - so it may allocate multiple pages 
> >> from
> >> start/end depending on Highmem memory or not - implying asynchronous 
> >> allocation
> >> and mapping.
> >
> > I thought it had some logic to figure out that it already handled this
> > page and would return an already allocate page?
> Right.
> I think the problem lies in the vm_insert_pfn/page/mixed family of functions.
> These are only used (grep'ed kernel tree) and invariably for mmaping.
> Scsi-tgt, mspec, some media/video, poch,android in staging and ttm
> - and, surprise - xen/blktap/ring.c and device.c
> - which both check XENFEAT_auto_translated_physmap
> Pls. look at xen/blktap/ring.c - it looks to be what we need

Let me take a look at it tomorrow. Bit swamped.

Xen-devel mailing list