From: Arnd Bergmann <arnd@arndb.de>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
"Semwal, Sumit" <sumit.semwal@ti.com>,
linux@arm.linux.org.uk, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
linux-mm@kvack.org, linux-media@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [Linaro-mm-sig] [RFC v2 1/2] dma-buf: Introduce dma buffer sharing mechanism
Date: Mon, 12 Dec 2011 16:48:51 +0000 [thread overview]
Message-ID: <201112121648.52126.arnd@arndb.de> (raw)
In-Reply-To: <CAKMK7uH+4uSYYjBLcvfhVC+iwGUZ09Z4p64fNBzh196aG+hqgg@mail.gmail.com>
On Saturday 10 December 2011, Daniel Vetter wrote:
> If userspace (through some driver calls)
> tries to do stupid things, it'll just get garbage. See
> Message-ID: <CAKMK7uHeXYn-v_8cmpLNWsFY14KtmuRZy8YRKR5Xst2-2WdFSQ@mail.gmail.com>
> for my reasons why it think this is the right way to go forward. So in
> essence I'm really interested in the reasons why you want the kernel
> to enforce this (or I'm completely missing what's the contentious
> issue here).
This has nothing to do with user space mappings. Whatever user space does,
you get garbage if you don't invalidate cache lines that were introduced
through speculative prefetching before you access cache lines that were
DMA'd from a device.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
"Semwal, Sumit" <sumit.semwal@ti.com>,
linux@arm.linux.org.uk, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
linux-mm@kvack.org, linux-media@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [Linaro-mm-sig] [RFC v2 1/2] dma-buf: Introduce dma buffer sharing mechanism
Date: Mon, 12 Dec 2011 16:48:51 +0000 [thread overview]
Message-ID: <201112121648.52126.arnd@arndb.de> (raw)
In-Reply-To: <CAKMK7uH+4uSYYjBLcvfhVC+iwGUZ09Z4p64fNBzh196aG+hqgg@mail.gmail.com>
On Saturday 10 December 2011, Daniel Vetter wrote:
> If userspace (through some driver calls)
> tries to do stupid things, it'll just get garbage. See
> Message-ID: <CAKMK7uHeXYn-v_8cmpLNWsFY14KtmuRZy8YRKR5Xst2-2WdFSQ@mail.gmail.com>
> for my reasons why it think this is the right way to go forward. So in
> essence I'm really interested in the reasons why you want the kernel
> to enforce this (or I'm completely missing what's the contentious
> issue here).
This has nothing to do with user space mappings. Whatever user space does,
you get garbage if you don't invalidate cache lines that were introduced
through speculative prefetching before you access cache lines that were
DMA'd from a device.
Arnd
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WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [Linaro-mm-sig] [RFC v2 1/2] dma-buf: Introduce dma buffer sharing mechanism
Date: Mon, 12 Dec 2011 16:48:51 +0000 [thread overview]
Message-ID: <201112121648.52126.arnd@arndb.de> (raw)
In-Reply-To: <CAKMK7uH+4uSYYjBLcvfhVC+iwGUZ09Z4p64fNBzh196aG+hqgg@mail.gmail.com>
On Saturday 10 December 2011, Daniel Vetter wrote:
> If userspace (through some driver calls)
> tries to do stupid things, it'll just get garbage. See
> Message-ID: <CAKMK7uHeXYn-v_8cmpLNWsFY14KtmuRZy8YRKR5Xst2-2WdFSQ@mail.gmail.com>
> for my reasons why it think this is the right way to go forward. So in
> essence I'm really interested in the reasons why you want the kernel
> to enforce this (or I'm completely missing what's the contentious
> issue here).
This has nothing to do with user space mappings. Whatever user space does,
you get garbage if you don't invalidate cache lines that were introduced
through speculative prefetching before you access cache lines that were
DMA'd from a device.
Arnd
next prev parent reply other threads:[~2011-12-12 16:49 UTC|newest]
Thread overview: 198+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-02 8:57 [RFC v2 0/2] Introduce DMA buffer sharing mechanism Sumit Semwal
2011-12-02 8:57 ` Sumit Semwal
2011-12-02 8:57 ` Sumit Semwal
2011-12-02 8:57 ` [RFC v2 1/2] dma-buf: Introduce dma " Sumit Semwal
2011-12-02 8:57 ` Sumit Semwal
2011-12-02 17:11 ` Konrad Rzeszutek Wilk
2011-12-02 17:11 ` Konrad Rzeszutek Wilk
2011-12-02 17:11 ` Konrad Rzeszutek Wilk
2011-12-05 9:48 ` Semwal, Sumit
2011-12-05 9:48 ` Semwal, Sumit
2011-12-05 9:48 ` Semwal, Sumit
2011-12-05 17:18 ` Arnd Bergmann
2011-12-05 17:18 ` Arnd Bergmann
2011-12-05 17:18 ` Arnd Bergmann
2011-12-05 18:55 ` Daniel Vetter
2011-12-05 18:55 ` Daniel Vetter
2011-12-05 18:55 ` Daniel Vetter
2011-12-05 19:29 ` Arnd Bergmann
2011-12-05 19:29 ` Arnd Bergmann
2011-12-05 19:29 ` Arnd Bergmann
2011-12-05 20:58 ` Daniel Vetter
2011-12-05 20:58 ` Daniel Vetter
2011-12-05 20:58 ` Daniel Vetter
2011-12-05 22:04 ` Arnd Bergmann
2011-12-05 22:04 ` Arnd Bergmann
2011-12-05 22:04 ` Arnd Bergmann
2011-12-05 22:33 ` Daniel Vetter
2011-12-05 22:33 ` Daniel Vetter
2011-12-05 22:33 ` Daniel Vetter
2011-12-05 20:46 ` Rob Clark
2011-12-05 20:46 ` Rob Clark
2011-12-05 20:46 ` Rob Clark
2011-12-05 21:23 ` Daniel Vetter
2011-12-05 21:23 ` Daniel Vetter
2011-12-05 21:23 ` Daniel Vetter
2011-12-05 22:11 ` Rob Clark
2011-12-05 22:11 ` Rob Clark
2011-12-05 22:11 ` Rob Clark
2011-12-05 22:33 ` Daniel Vetter
2011-12-05 22:33 ` Daniel Vetter
2011-12-05 22:33 ` Daniel Vetter
2011-12-06 13:16 ` Arnd Bergmann
2011-12-06 13:16 ` Arnd Bergmann
2011-12-06 13:16 ` Arnd Bergmann
2011-12-06 15:28 ` Daniel Vetter
2011-12-06 15:28 ` Daniel Vetter
2011-12-06 15:28 ` Daniel Vetter
2011-12-07 13:27 ` Semwal, Sumit
2011-12-07 13:27 ` Semwal, Sumit
2011-12-07 13:27 ` Semwal, Sumit
2011-12-07 13:40 ` Arnd Bergmann
2011-12-07 13:40 ` Arnd Bergmann
2011-12-07 13:40 ` Arnd Bergmann
2011-12-08 21:44 ` [Linaro-mm-sig] " Daniel Vetter
2011-12-08 21:44 ` Daniel Vetter
2011-12-08 21:44 ` Daniel Vetter
2011-12-09 14:13 ` Arnd Bergmann
2011-12-09 14:13 ` Arnd Bergmann
2011-12-09 14:13 ` Arnd Bergmann
2011-12-09 14:24 ` Alan Cox
2011-12-09 14:24 ` Alan Cox
2011-12-09 14:24 ` Alan Cox
2011-12-10 4:01 ` Daniel Vetter
2011-12-10 4:01 ` Daniel Vetter
2011-12-10 4:01 ` Daniel Vetter
2011-12-12 16:48 ` Arnd Bergmann [this message]
2011-12-12 16:48 ` Arnd Bergmann
2011-12-12 16:48 ` Arnd Bergmann
2011-12-19 6:16 ` Semwal, Sumit
2011-12-19 6:16 ` Semwal, Sumit
2011-12-19 6:16 ` Semwal, Sumit
2011-12-20 15:41 ` Arnd Bergmann
2011-12-20 15:41 ` Arnd Bergmann
2011-12-20 15:41 ` Arnd Bergmann
2011-12-20 16:41 ` Rob Clark
2011-12-20 16:41 ` Rob Clark
2011-12-20 16:41 ` Rob Clark
2011-12-20 17:14 ` Daniel Vetter
2011-12-20 17:14 ` Daniel Vetter
2011-12-20 17:14 ` Daniel Vetter
2011-12-20 17:14 ` Daniel Vetter
2011-12-21 17:27 ` Arnd Bergmann
2011-12-21 17:27 ` Arnd Bergmann
2011-12-21 17:27 ` Arnd Bergmann
2011-12-21 19:04 ` Daniel Vetter
2011-12-21 19:04 ` Daniel Vetter
2011-12-21 19:04 ` Daniel Vetter
2011-12-23 10:00 ` Semwal, Sumit
2011-12-23 10:00 ` Semwal, Sumit
2011-12-23 10:00 ` Semwal, Sumit
2011-12-23 17:10 ` Rob Clark
2011-12-23 17:10 ` Rob Clark
2011-12-23 17:10 ` Rob Clark
2011-12-20 9:03 ` Sakari Ailus
2011-12-20 9:03 ` Sakari Ailus
2011-12-20 9:03 ` Sakari Ailus
2011-12-20 15:36 ` Arnd Bergmann
2011-12-20 15:36 ` Arnd Bergmann
2011-12-20 15:36 ` Arnd Bergmann
2012-01-01 20:53 ` Sakari Ailus
2012-01-01 20:53 ` Sakari Ailus
2012-01-01 20:53 ` Sakari Ailus
2012-01-01 23:12 ` Rob Clark
2012-01-01 23:12 ` Rob Clark
2012-01-01 23:12 ` Rob Clark
2011-12-13 13:33 ` Hans Verkuil
2011-12-13 13:33 ` Hans Verkuil
2011-12-13 13:33 ` Hans Verkuil
2011-12-05 22:09 ` Arnd Bergmann
2011-12-05 22:09 ` Arnd Bergmann
2011-12-05 22:09 ` Arnd Bergmann
2011-12-05 22:09 ` Arnd Bergmann
2011-12-05 22:15 ` Rob Clark
2011-12-05 22:15 ` Rob Clark
2011-12-05 22:15 ` Rob Clark
2011-12-05 22:35 ` Rob Clark
2011-12-05 22:35 ` Rob Clark
2011-12-05 22:35 ` Rob Clark
2011-12-07 6:35 ` Semwal, Sumit
2011-12-07 6:35 ` Semwal, Sumit
2011-12-07 6:35 ` Semwal, Sumit
2011-12-07 10:11 ` Arnd Bergmann
2011-12-07 10:11 ` Arnd Bergmann
2011-12-07 10:11 ` Arnd Bergmann
2011-12-07 11:02 ` Semwal, Sumit
2011-12-07 11:02 ` Semwal, Sumit
2011-12-07 11:02 ` Semwal, Sumit
2011-12-07 11:34 ` Arnd Bergmann
2011-12-07 11:34 ` Arnd Bergmann
2011-12-07 11:34 ` Arnd Bergmann
2011-12-09 22:50 ` [Linaro-mm-sig] " Robert Morell
2011-12-09 22:50 ` Robert Morell
2011-12-09 22:50 ` Robert Morell
2011-12-09 22:50 ` Robert Morell
2011-12-10 11:13 ` Mauro Carvalho Chehab
2011-12-10 11:13 ` Mauro Carvalho Chehab
2011-12-10 11:13 ` Mauro Carvalho Chehab
2011-12-10 11:13 ` Mauro Carvalho Chehab
2011-12-12 22:44 ` Robert Morell
2011-12-12 22:44 ` Robert Morell
2011-12-12 22:44 ` Robert Morell
2011-12-12 22:44 ` Robert Morell
2011-12-13 15:10 ` Arnd Bergmann
2011-12-13 15:10 ` Arnd Bergmann
2011-12-13 15:10 ` Arnd Bergmann
2011-12-13 15:10 ` Arnd Bergmann
2011-12-20 2:05 ` Robert Morell
2011-12-20 2:05 ` Robert Morell
2011-12-20 2:05 ` Robert Morell
2011-12-20 2:05 ` Robert Morell
2011-12-20 14:29 ` Anca Emanuel
2011-12-20 14:29 ` Anca Emanuel
2011-12-20 14:29 ` Anca Emanuel
2011-12-20 14:29 ` Anca Emanuel
2012-01-09 6:20 ` InKi Dae
2012-01-09 6:20 ` InKi Dae
2012-01-09 6:20 ` InKi Dae
2012-01-09 8:10 ` Daniel Vetter
2012-01-09 8:10 ` Daniel Vetter
2012-01-09 8:10 ` Daniel Vetter
2012-01-09 8:11 ` [Linaro-mm-sig] " Dave Airlie
2012-01-09 8:11 ` Dave Airlie
2012-01-09 8:11 ` Dave Airlie
2012-01-09 10:10 ` InKi Dae
2012-01-09 10:10 ` InKi Dae
2012-01-09 10:10 ` InKi Dae
2012-01-09 10:27 ` Daniel Vetter
2012-01-09 10:27 ` Daniel Vetter
2012-01-09 10:27 ` Daniel Vetter
2012-01-09 12:06 ` InKi Dae
2012-01-09 12:06 ` InKi Dae
2012-01-09 12:06 ` InKi Dae
2012-01-09 16:02 ` Daniel Vetter
2012-01-09 16:02 ` Daniel Vetter
2012-01-09 16:02 ` Daniel Vetter
2012-01-09 15:17 ` Rob Clark
2012-01-09 15:17 ` Rob Clark
2012-01-09 15:17 ` Rob Clark
2012-01-10 1:34 ` InKi Dae
2012-01-10 1:34 ` InKi Dae
2012-01-10 1:34 ` InKi Dae
2012-01-10 2:14 ` Rob Clark
2012-01-10 2:14 ` Rob Clark
2012-01-10 2:14 ` Rob Clark
2012-01-10 6:09 ` Semwal, Sumit
2012-01-10 6:09 ` Semwal, Sumit
2012-01-10 6:09 ` Semwal, Sumit
2012-01-10 7:28 ` InKi Dae
2012-01-10 7:28 ` InKi Dae
2012-01-10 7:28 ` InKi Dae
2012-01-10 9:19 ` InKi Dae
2012-01-10 9:19 ` InKi Dae
2012-01-10 9:19 ` InKi Dae
2012-01-11 1:08 ` InKi Dae
2012-01-11 1:08 ` InKi Dae
2012-01-11 1:08 ` InKi Dae
2011-12-02 8:57 ` [RFC v2 2/2] dma-buf: Documentation for buffer sharing framework Sumit Semwal
2011-12-02 8:57 ` Sumit Semwal
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