From: Gerd Hoffmann <kraxel@redhat.com>
To: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@linux.ie>, Sean Paul <sean@poorly.run>,
Emil Velikov <emil.l.velikov@gmail.com>,
dri-devel <dri-devel@lists.freedesktop.org>,
Sam Ravnborg <sam@ravnborg.org>
Subject: Re: [PATCH 1/2] drm/shmem: Use cached mappings by default
Date: Mon, 18 May 2020 10:23:54 +0200 [thread overview]
Message-ID: <20200518082354.jeuyt7uzek73pjkp@sirius.home.kraxel.org> (raw)
In-Reply-To: <3e09cc7d-c609-e10a-3fe9-f40f3bbfaeaf@suse.de>
> > $ git grep drm_gem_shmem_mmap
> >
> > We also need correct access from userspace, otherwise the gpu is going to
> > be sad.
>
> I've been thinking about this, and I think it means that we can never
> have cached mappings anywhere. Even if shmem supports it internally for
> most drivers, as soon as the page are exported, the importer could
> expect uncached memory.
The importer should not expect anything but call dma-buf ops so the
exporter has a chance to handle this correctly.
(Yes, we don't get this right everywhere, some drivers take the dma-bufs
list of pages and do their own thing ...).
take care,
Gerd
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next prev parent reply other threads:[~2020-05-18 8:24 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-13 15:03 [PATCH 0/2] Default to cachable mappings for GEM SHMEM Thomas Zimmermann
2020-05-13 15:03 ` [PATCH 1/2] drm/shmem: Use cached mappings by default Thomas Zimmermann
2020-05-13 15:06 ` Thomas Zimmermann
2020-05-14 12:40 ` Daniel Vetter
2020-05-14 15:27 ` Thomas Zimmermann
2020-05-14 20:36 ` Rob Herring
2020-05-15 6:58 ` Thomas Zimmermann
2020-05-15 14:10 ` Daniel Vetter
2020-05-18 8:13 ` Thomas Zimmermann
2020-05-18 8:23 ` Gerd Hoffmann [this message]
2020-05-18 8:50 ` Thomas Zimmermann
2020-05-18 10:11 ` Gerd Hoffmann
2020-05-18 14:40 ` Daniel Vetter
2020-05-19 6:31 ` Thomas Zimmermann
2020-05-13 15:03 ` [PATCH 2/2] drm/udl: Use GEM vmap/mmap function from SHMEM helpers Thomas Zimmermann
2020-05-13 15:49 ` Daniel Vetter
2020-05-13 17:19 ` Thomas Zimmermann
2020-05-14 12:44 ` Daniel Vetter
2020-05-19 6:36 ` Thomas Zimmermann
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