* [PATCH] drm/bochs: fix bochs_gem_prime_mmap
@ 2019-02-04 18:38 Gerd Hoffmann
2019-02-05 9:01 ` Daniel Vetter
0 siblings, 1 reply; 2+ messages in thread
From: Gerd Hoffmann @ 2019-02-04 18:38 UTC (permalink / raw)
To: dri-devel
Cc: Gerd Hoffmann, David Airlie, Daniel Vetter,
open list:DRM DRIVER FOR BOCHS VIRTUAL GPU, open list
ttm_fbdev_mmap() just doesn't work. It appears to work fine, mmap()
returns success, but any attempt to actually access the mapping causes a
SIGBUS.
We can just use drm_gem_prime_mmap() instead. Almost. We have to copy
over the start offset from the ttm_buffer_object vm_node to the
drm_gem_object vm_node so the offset math in drm_gem_prime_mmap() works
correctly for us even though we use ttm to manage our objects.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
drivers/gpu/drm/bochs/bochs_mm.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/bochs/bochs_mm.c b/drivers/gpu/drm/bochs/bochs_mm.c
index 641a33f134..49463348a0 100644
--- a/drivers/gpu/drm/bochs/bochs_mm.c
+++ b/drivers/gpu/drm/bochs/bochs_mm.c
@@ -442,5 +442,6 @@ int bochs_gem_prime_mmap(struct drm_gem_object *obj,
{
struct bochs_bo *bo = gem_to_bochs_bo(obj);
- return ttm_fbdev_mmap(vma, &bo->bo);
+ bo->gem.vma_node.vm_node.start = bo->bo.vma_node.vm_node.start;
+ return drm_gem_prime_mmap(obj, vma);
}
--
2.9.3
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] drm/bochs: fix bochs_gem_prime_mmap
2019-02-04 18:38 [PATCH] drm/bochs: fix bochs_gem_prime_mmap Gerd Hoffmann
@ 2019-02-05 9:01 ` Daniel Vetter
0 siblings, 0 replies; 2+ messages in thread
From: Daniel Vetter @ 2019-02-05 9:01 UTC (permalink / raw)
To: Gerd Hoffmann
Cc: dri-devel, David Airlie, Daniel Vetter,
open list:DRM DRIVER FOR BOCHS VIRTUAL GPU, open list
On Mon, Feb 04, 2019 at 07:38:58PM +0100, Gerd Hoffmann wrote:
> ttm_fbdev_mmap() just doesn't work. It appears to work fine, mmap()
> returns success, but any attempt to actually access the mapping causes a
> SIGBUS.
>
> We can just use drm_gem_prime_mmap() instead. Almost. We have to copy
> over the start offset from the ttm_buffer_object vm_node to the
> drm_gem_object vm_node so the offset math in drm_gem_prime_mmap() works
> correctly for us even though we use ttm to manage our objects.
>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Would be kinda neat if we could teach ttm to not have it's own vma node
...
Anyway, lgtm.
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
> drivers/gpu/drm/bochs/bochs_mm.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bochs/bochs_mm.c b/drivers/gpu/drm/bochs/bochs_mm.c
> index 641a33f134..49463348a0 100644
> --- a/drivers/gpu/drm/bochs/bochs_mm.c
> +++ b/drivers/gpu/drm/bochs/bochs_mm.c
> @@ -442,5 +442,6 @@ int bochs_gem_prime_mmap(struct drm_gem_object *obj,
> {
> struct bochs_bo *bo = gem_to_bochs_bo(obj);
>
> - return ttm_fbdev_mmap(vma, &bo->bo);
> + bo->gem.vma_node.vm_node.start = bo->bo.vma_node.vm_node.start;
> + return drm_gem_prime_mmap(obj, vma);
> }
> --
> 2.9.3
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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