Arvind R wrote:
On Thu, Mar 11, 2010 at 4:32 PM, Pekka Paalanen <[email protected]> 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-de...@.
Thanks.
This is a NAK in its current form.
First, At mmap() time, the placement may not be known, and even if it is
known, the placement may change.
Second, VM_IO is used to avoid including bos in core dumps, and make
sure get_user_pages() isn't lazily called on BOs. That would cause the
lock inversion prevention to fail.
Third, I'm not sure the Xen strategy will work for VM_MIXEDMAP, which
may contain both IO- and real pages?
Thanks,
Thomas
On Wed, 10 Mar 2010 18:51:21 +0530
Arvind R <[email protected]> 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!
Arvind R.
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