From: Chris Wilson <chris@chris-wilson.co.uk>
To: lepton <ytht.net@gmail.com>
Cc: Thomas Hellström <thomas_os@shipmail.org>,
"# v4 . 10+" <stable@vger.kernel.org>,
Christian König <christian.koenig@amd.com>,
dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/2] drm/vgem: Do not allocate backing shmemfs file for an import dmabuf object
Date: Tue, 07 Jul 2020 18:20:32 +0100 [thread overview]
Message-ID: <159414243217.17526.6453360763938648186@build.alporthouse.com> (raw)
In-Reply-To: <CALqoU4y61Yc5ndaLSO3WoGSPxGm1nJJufk3U=uxhZe3sT1Xyzg@mail.gmail.com>
Quoting lepton (2020-07-07 18:05:21)
> On Tue, Jul 7, 2020 at 9:00 AM Chris Wilson <chris@chris-wilson.co.uk> wrote:
> >
> > If we assign obj->filp, we believe that the create vgem bo is native and
> > allow direct operations like mmap() assuming it behaves as backed by a
> > shmemfs inode. When imported from a dmabuf, the obj->pages are
> > not always meaningful and the shmemfs backing store misleading.
> >
> > Note, that regular mmap access to a vgem bo is via the dumb buffer API,
> > and that rejects attempts to mmap an imported dmabuf,
> What do you mean by "regular mmap access" here? It looks like vgem is
> using vgem_gem_dumb_map as .dumb_map_offset callback then it doesn't call
> drm_gem_dumb_map_offset
As I too found out, and so had to correct my story telling.
By regular mmap() access I mean mmap on the vgem bo [via the dumb buffer
API] as opposed to mmap() via an exported dma-buf fd. I had to look at
igt to see how it was being used.
-Chris
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next prev parent reply other threads:[~2020-07-07 17:20 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-07 16:00 [PATCH 1/2] drm/vgem: Do not allocate backing shmemfs file for an import dmabuf object Chris Wilson
2020-07-07 16:00 ` [PATCH 2/2] drm/vgem: Replace opencoded version of drm_gem_dumb_map_offset() Chris Wilson
2020-07-08 9:56 ` Daniel Vetter
2020-07-08 14:53 ` Chris Wilson
2020-07-07 17:05 ` [PATCH 1/2] drm/vgem: Do not allocate backing shmemfs file for an import dmabuf object lepton
2020-07-07 17:20 ` Chris Wilson [this message]
2020-07-07 18:17 ` lepton
2020-07-07 18:35 ` Chris Wilson
2020-07-08 9:22 ` Christian König
2020-07-08 9:54 ` Daniel Vetter
2020-07-08 14:37 ` Christian König
2020-07-08 15:01 ` Daniel Vetter
2020-07-08 15:05 ` Christian König
2020-07-08 16:11 ` Daniel Vetter
2020-07-08 16:19 ` Daniel Vetter
2020-07-09 8:48 ` Christian König
2020-07-09 13:54 ` Steven Price
2020-07-09 14:15 ` Christian König
2020-07-09 8:49 ` Christian König
2020-07-08 5:44 ` lepton
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