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From: Christoph Hellwig <hch@lst•de>
To: Rob Clark <robdclark@chromium•org>
Cc: Mark Rutland <mark.rutland@arm•com>,
	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 09:59:47 +0200	[thread overview]
Message-ID: <20190808075947.GE30308@lst.de> (raw)
In-Reply-To: <CAJs_Fx71T=kJEgt28TWqzw+jOahSbLQynCg83+szQW7op4xBkQ@mail.gmail.com>

On Wed, Aug 07, 2019 at 10:30:04AM -0700, Rob Clark wrote:
> So, we do end up using GFP_HIGHUSER, which appears to get passed thru
> when shmem gets to the point of actually allocating pages.. not sure
> if that just ends up being a hint, or if it guarantees that we don't
> get something in the linear map.
> 
> (Bear with me while I "page" this all back in.. last time I dug thru
> the shmem code was probably pre-armv8, or at least before I had any
> armv8 hw)

GFP_HIGHUSER basically just means that this is an allocation that could
dip into highmem, in which case it would not have a kernel mapping.
This can happen on arm + LPAE, but not on arm64.

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  reply	other threads:[~2019-08-08  8:00 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 [this message]
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
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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