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From: Christoph Hellwig <hch@lst•de>
To: Mark Rutland <mark.rutland@arm•com>
Cc: Rob Clark <robdclark@chromium•org>,
	Maxime Ripard <maxime.ripard@bootlin•com>,
	Catalin Marinas <catalin.marinas@arm•com>,
	David Airlie <airlied@linux•ie>,
	Maarten Lankhorst <maarten.lankhorst@linux•intel.com>,
	LKML <linux-kernel@vger•kernel.org>,
	dri-devel <dri-devel@lists•freedesktop.org>,
	Sean Paul <sean@poorly•run>, Rob Clark <robdclark@gmail•com>,
	linux-arm-kernel@lists•infradead.org,
	Daniel Vetter <daniel@ffwll•ch>,
	Greg Kroah-Hartman <gregkh@linuxfoundation•org>,
	Thomas Gleixner <tglx@linutronix•de>,
	Will Deacon <will@kernel•org>, Christoph Hellwig <hch@lst•de>,
	Allison Randal <allison@lohutok•net>
Subject: Re: [PATCH 1/2] drm: add cache support for arm64
Date: Thu, 8 Aug 2019 09:53:51 +0200	[thread overview]
Message-ID: <20190808075351.GC30308@lst.de> (raw)
In-Reply-To: <20190807123807.GD54191@lakrids.cambridge.arm.com>

On Wed, Aug 07, 2019 at 01:38:08PM +0100, Mark Rutland wrote:
> > I *believe* that there are not alias mappings (that I don't control
> > myself) for pages coming from
> > shmem_file_setup()/shmem_read_mapping_page()..  
> 
> AFAICT, that's regular anonymous memory, so there will be a cacheable
> alias in the linear/direct map.

Yes.  Although shmem is in no way special in that regard.  Even with the
normal dma_alloc_coherent implementation on arm and arm64 we keep the
cacheable alias in the direct mapping and just create a new non-cacheable
one.  The only exception are CMA allocations on 32-bit arm, which do
get remapped to uncachable in place.

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  parent reply	other threads:[~2019-08-08  7:54 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-05 21:14 [PATCH 1/2] drm: add cache support for arm64 Rob Clark
2019-08-06  8:48 ` Christoph Hellwig
2019-08-06  9:38   ` Daniel Vetter
2019-08-06 11:38     ` Christoph Hellwig
2019-08-06 14:11   ` Rob Clark
2019-08-06 14:34     ` Mark Rutland
2019-08-06 16:31       ` Rob Clark
2019-08-07 12:38         ` Mark Rutland
2019-08-07 16:15           ` Rob Clark
2019-08-07 16:49             ` Mark Rutland
2019-08-07 17:30               ` Rob Clark
2019-08-08  7:59                 ` Christoph Hellwig
2019-08-08 16:44                   ` Rob Clark
2019-08-09  8:18                     ` Christoph Hellwig
2019-08-08  7:58               ` Christoph Hellwig
2019-08-08 10:20                 ` Mark Rutland
2019-08-08 10:24                   ` Mark Rutland
2019-08-08 10:32                   ` Will Deacon
2019-08-08  7:53           ` Christoph Hellwig [this message]
2019-08-06 15:50     ` Christoph Hellwig
2019-08-06 16:23       ` Rob Clark
2019-08-06 16:26         ` Rob Clark
2019-08-07  6:25         ` Christoph Hellwig
2019-08-07  8:48           ` Daniel Vetter
2019-08-08  9:55             ` Christoph Hellwig
2019-08-08 11:58               ` Daniel Vetter
2019-08-09  8:14                 ` Christoph Hellwig
2019-08-07 16:09           ` Rob Clark
2019-08-08 10:00             ` Christoph Hellwig
2019-08-08 16:32               ` Rob Clark

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