linux-kernel - Re: [PATCH v2 07/11] drm/ttm: drop VM

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Message-ID: <c29222f7-2737-2416-62c9-eafd4d608ded@amd.com>
Date:   Tue, 17 Sep 2019 11:22:35 +0000
From:   "Koenig, Christian" <Christian.Koenig@....com>
To:     Gerd Hoffmann <kraxel@...hat.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
CC:     Thomas Zimmermann <tzimmermann@...e.de>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        "Huang, Ray" <Ray.Huang@....com>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 07/11] drm/ttm: drop VM_DONTDUMP

Am 17.09.19 um 11:24 schrieb Gerd Hoffmann:
> Not obvious why this is needed.  According to Deniel Vetter this is most
> likely a historic artefact dating back to the days where drm drivers
> exposed hardware registers as mmap'able gem objects, to avoid dumping
> touching those registers.

Clearly a NAK.

We still have that and really don't want to try dumping any CPU 
inaccessible VRAM content even if it is mapped into the address space 
somewhere.

Regards,
Christian.

>
> Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>
> ---
>   drivers/gpu/drm/ttm/ttm_bo_vm.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index 7c0e85c10e0e..4dc77a66aaf6 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -445,7 +445,7 @@ void ttm_bo_mmap_vma_setup(struct ttm_buffer_object *bo, struct vm_area_struct *
>   	 * VM_MIXEDMAP on all mappings. See freedesktop.org bug #75719
>   	 */
>   	vma->vm_flags |= VM_MIXEDMAP;
> -	vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
> +	vma->vm_flags |= VM_IO | VM_DONTEXPAND;
>   }
>   EXPORT_SYMBOL(ttm_bo_mmap_vma_setup);
>