From: Christoph Hellwig <hch@lst.de>
To: Arnd Bergmann <arnd@linaro.org>
Cc: Sagi Grimberg <sagi@grimberg.me>, Christoph Hellwig <hch@lst.de>,
Nikita Yushchenko <nikita.yoush@cogentembedded.com>,
linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
Simon Horman <horms@verge.net.au>,
linux-pci@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
artemi.ivanov@cogentembedded.com,
Keith Busch <keith.busch@intel.com>, Jens Axboe <axboe@fb.com>,
linux-nvme@lists.infradead.org
Subject: Re: NVMe vs DMA addressing limitations
Date: Thu, 12 Jan 2017 14:07:52 +0100 [thread overview]
Message-ID: <20170112130752.GA14465@lst.de> (raw)
In-Reply-To: <3306663.hKmLLq1hhl@wuerfel>
On Thu, Jan 12, 2017 at 12:56:07PM +0100, Arnd Bergmann wrote:
> That is an interesting question: We actually have the
> "DMA_ATTR_NO_KERNEL_MAPPING" for this case, and ARM implements
> it in the coherent interface, so that might be a good fit.
Yes. my WIP HMB patch uses DMA_ATTR_NO_KERNEL_MAPPING, although I'm
workin on x86 at the moment where it's a no-op.
> Implementing it in the streaming API makes no sense since we
> already have a kernel mapping here, but using a normal allocation
> (possibly with DMA_ATTR_NON_CONSISTENT or DMA_ATTR_SKIP_CPU_SYNC,
> need to check) might help on other architectures that have
> limited amounts of coherent memory and no CMA.
Though about that - but in the end DMA_ATTR_NO_KERNEL_MAPPING implies
those, so instead of using lots of flags in driver I'd rather fix
up more dma_ops implementations to take advantage of
DMA_ATTR_NO_KERNEL_MAPPING.
next prev parent reply other threads:[~2017-01-12 13:07 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-29 20:45 [PATCH 1/2] arm64: dma_mapping: allow PCI host driver to limit DMA mask Nikita Yushchenko
2016-12-29 20:45 ` [PATCH 2/2] rcar-pcie: set host bridge's " Nikita Yushchenko
2016-12-29 21:18 ` [PATCH 1/2] arm64: dma_mapping: allow PCI host driver to limit " Arnd Bergmann
2016-12-30 9:46 ` Sergei Shtylyov
2016-12-30 10:06 ` Sergei Shtylyov
2017-01-03 18:44 ` Will Deacon
2017-01-03 19:01 ` Nikita Yushchenko
2017-01-03 20:13 ` Grygorii Strashko
2017-01-03 20:23 ` Nikita Yushchenko
2017-01-03 23:13 ` Arnd Bergmann
2017-01-04 6:24 ` Nikita Yushchenko
2017-01-04 13:29 ` Arnd Bergmann
2017-01-04 14:30 ` Nikita Yushchenko
2017-01-04 14:46 ` Arnd Bergmann
2017-01-04 15:29 ` Nikita Yushchenko
2017-01-06 11:10 ` Arnd Bergmann
2017-01-06 13:47 ` Nikita Yushchenko
2017-01-06 14:38 ` [PATCH] arm64: do not set dma masks that device connection can't handle Nikita Yushchenko
2017-01-06 14:45 ` Nikita Yushchenko
2017-01-08 7:09 ` Sergei Shtylyov
2017-01-09 6:56 ` Nikita Yushchenko
2017-01-09 14:05 ` [PATCH 1/2] arm64: dma_mapping: allow PCI host driver to limit DMA mask Arnd Bergmann
2017-01-09 20:34 ` Nikita Yushchenko
2017-01-09 20:57 ` Christoph Hellwig
2017-01-10 6:47 ` NVMe vs DMA addressing limitations Nikita Yushchenko
2017-01-10 7:07 ` Christoph Hellwig
2017-01-10 7:31 ` Nikita Yushchenko
2017-01-10 11:01 ` Arnd Bergmann
2017-01-10 14:48 ` Christoph Hellwig
2017-01-10 15:02 ` Arnd Bergmann
2017-01-12 10:09 ` Sagi Grimberg
2017-01-12 11:56 ` Arnd Bergmann
2017-01-12 13:07 ` Christoph Hellwig [this message]
2017-01-10 10:54 ` Arnd Bergmann
2017-01-10 10:47 ` [PATCH 1/2] arm64: dma_mapping: allow PCI host driver to limit DMA mask Arnd Bergmann
2017-01-10 14:44 ` Christoph Hellwig
2017-01-10 15:00 ` Arnd Bergmann
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