From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
bart.vanassche@sandisk.com,
Alexander Duyck <alexander.h.duyck@intel.com>,
Krzysztof Kozlowski <k.kozlowski@samsung.com>,
Andrew Morton <akpm@linux-foundation.org>,
lkml <linux-kernel@vger.kernel.org>,
arcml <linux-snps-arc@lists.infradead.org>
Subject: Re: semantics of dma_map_single()
Date: Mon, 17 Jul 2017 09:06:29 -0700 [thread overview]
Message-ID: <23203d16-da54-99c7-0eba-c082eba120d7@synopsys.com> (raw)
In-Reply-To: <20170717064220.GA15807@lst.de>
Hi Christoph,
On 07/16/2017 11:42 PM, Christoph Hellwig wrote:
> I would expect that it would support any contiguous range in
> the kernel mapping (e.g. no vmalloc and friends). But it's not
> documented anywhere, and if no in kernel users makes use of that
> fact at the moment it might be better to document a page size
> limitation and add asserts to enforce it.
My first thought was indeed to add a BUG_ON for @size > PAGE_SIZE (also accounting
for offset etc), but I have a feeling this will cause too many breakages. So
perhaps it would be better to add the fact to Documentation that it can handle any
physically contiguous range.
-Vineet
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next prev parent reply other threads:[~2017-07-17 16:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-16 1:24 semantics of dma_map_single() Vineet Gupta
2017-07-17 6:42 ` Christoph Hellwig
2017-07-17 16:06 ` Vineet Gupta [this message]
2017-07-17 16:46 ` James Bottomley
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