Re: [Xen-devel] Re: [Patch RFC] ttm: nouveau accelerated on Xen pv-ops kernel

[Michael D Labriola <mlabriol@xxxxxxxx>]

xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 03/13/2010 05:03:22 PM:

> On 03/12/2010 01:45 PM, Arvind R wrote:
> > On Thu, Mar 11, 2010 at 4:32 PM, Pekka Paalanen <pq@xxxxxx> wrote:
> >> I'm adding dri-devel@ to CC, since this suggested patch touches
> >> TTM code, and none of the Nouveau code. TTM patches go via
> >> dri-devel@.
> >>
> >> Thanks.
> >>
> >>
> >> On Wed, 10 Mar 2010 18:51:21 +0530
> >> Arvind R <arvino55@xxxxxxxxx> wrote:
> >>
> >>> Hi,
> >>> Following is a simple patch that is needed in nouveau to get
> >>> accelerated X on a Xen dom0 pv_ops kernel. The kernel is jeremy's
> >>> 2.6.31.6 as of 20100222. The whole gpu tree of nouveau (which is
> >>> almost the mainline merge), was substituted into the kernel-tree.
> >>> All components of X (mesa, Xorg-server-7.5, xf86-nouveau, libdrm)
> >>> used of the same day.
> >>>
> >>> Patch:
> >>> diff -Naur nouveau-kernel.orig/drivers/gpu/drm/ttm/ttm_bo_vm.c
> >>> nouveau-kernel.new/drivers/gpu/drm/ttm/ttm_bo_vm.c
> >>> --- nouveau-kernel.orig/drivers/gpu/drm/ttm/ttm_bo_vm.c 2010-01-27
> >>> 10:19:28.000000000 +0530
> >>> +++ nouveau-kernel.new/drivers/gpu/drm/ttm/ttm_bo_vm.c  2010-03-10
> >>> 17:28:59.000000000 +0530
> >>> @@ -271,7 +271,10 @@
> >>>          */
> >>>
> >>>         vma->vm_private_data = bo;
> >>> -       vma->vm_flags |= VM_RESERVED | VM_IO | VM_MIXEDMAP |
> >>> VM_DONTEXPAND;
> >>> +       vma->vm_flags |= VM_RESERVED | VM_MIXEDMAP |
> >>> VM_DONTEXPAND;
> >>> +       if (!((bo->mem.placement & TTM_PL_MASK_MEM) &
> >>> TTM_PL_FLAG_TT))
> >>> +               vma->vm_flags |= VM_IO;
> >>> +       vma->vm_page_prot = vma_get_vm_prot(vma->vm_flags);
> >>>         return 0;
> >>>  out_unref:
> >>>         ttm_bo_unref(&bo);
> >>>
> > sorry for the typo and other procedural errors.
> > the last added line should be
> > +    vma->vm_page_prot = vm_get_page_prot(vma->vm_flags)
> > 
> >>> This patch is necessary because, in Xen, PFN of a page is
> >>> virtualised. So physical addresses
> >>> for DMA programming needs to use the MFN. Xen transparently does
> >>> the correct translation
> >>> using the _PAGE_IOMEM prot-bit in the PTE. If the bit is set,
> >>> then Xen assumes that the backing
> >>> memory is in the IOMEM space, and PFN equals MFN. If not set,
> >>> page_to_pfn() returns MFN.
> >>>
> >>> The patch enables the ttm_bo_vm_fault() handler to behave
> >>> correctly under Xen, and has no
> >>> side-effects on normal (not under Xen) operations. The use of
> >>> TTM_PL_FLAG_TT in the
> >>> check assumes that all other placements are backed by device
> >>> memory or IO. If there are
> >>> any other placements that use system memory, that flag has to be
> >>> OR'ed into the check.
> >>>
> >>> The above patch has no implications on a normal kernel or a Xen
> >>> pv_ops kernel booted without
> >>> the Xen hypervisor. My testing is on a debian-lenny environment
> >>> on a Core2 processor with
> >>> nVidia GeForce 9400 GT.
> >>
> > Efficacy of patch:
> > successful flightgear run on dom0 AND bareboot!
> > 
> Jeremy, will you be merging this patch into any of the xen/stable-*
> branches any time soon?
> 
> Thanks,
> joanna.

Hmm... I just verified that this patch fixes KMS/Nouveau issues in Xen on 
my two primary test boxes (GeForce 6200, GeForce 7300).  However, on my 
really old machines (AGP GeForce2 MX200), this causes a new crash.  These 
old boxes were actually working fine in Xen prior to this patch, just 
w/out 3d acceleration.  Now I get the following messages in dmesg:

[  129.637319] [drm] nouveau 0000:01:00.0: Allocating FIFO number 1
[  129.638853] [drm] nouveau 0000:01:00.0: nouveau_channel_alloc: 
initialised FIFO 1
[  129.643791] X: Corrupted page table at address 40412000
[  129.643815] *pdpt = 0000000015216001 *pde = 0000000000000000 
[  129.643856] Bad pagetable: 000f [#1] SMP 
[  129.643897] last sysfs file: 
/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/boot_vga
[  129.643916] Modules linked in: bridge stp ipv6 autofs4 sunrpc raid1 
video output sbs sbshc pci_slot lp sg nouveau snd_intel8x0 snd_ac97_codec 
ac97_bus snd_seq_dummy he atm ttm drm_kms_helper snd_seq_oss 
snd_seq_midi_event sr_mod snd_seq cdrom drm serio_raw snd_seq_device 
snd_pcm_oss snd_mixer_oss snd_pcm e100 mii i2c_algo_bit snd_timer 
ata_generic snd pcspkr i2c_i801 i2c_core intel_rng soundcore i82860_edac 
snd_page_alloc pata_acpi edac_core parport_pc floppy parport dm_snapshot 
dm_zero dm_mirror dm_region_hash dm_log dm_mod raid0 ext3 mbcache jbd 
aic7xxx scsi_transport_spi ata_piix libata sd_mod scsi_mod
[  129.644024] 
[  129.644024] Pid: 3690, comm: X Not tainted (2.6.31.6-mdl5 #1) P4DC6
[  129.644024] EIP: 0073:[<40394596>] EFLAGS: 00210206 CPU: 0
[  129.644024] EIP is at 0x40394596
[  129.644024] EAX: 40412000 EBX: 40396cd8 ECX: 0909ee98 EDX: 00044000
[  129.644024] ESI: 00000034 EDI: 0909edd8 EBP: bfe7f798 ESP: bfe7f780
[  129.644024]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b
[  129.644024] Process X (pid: 3690, ti=ea1ce000 task=ea77f110 
task.ti=ea1ce000)
[  129.644024] 
[  129.644024] EIP: [<40394596>] 0x40394596 SS:ESP 007b:bfe7f780
[  129.644024] ---[ end trace 569eb18d737a8611 ]---
[  129.652216] [drm] nouveau 0000:01:00.0: nouveau_channel_free: freeing 
fifo 1


And my X log ends abruptly after this line:
(II) NOUVEAU(0): Opened GPU Channel 1

Any ideas?

-Mike

---
Michael D Labriola
Electric Boat
mlabriol@xxxxxxxx
401-848-8871 (desk)
401-848-8513 (lab)
401-316-9844 (cell)



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