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From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-kernel@vger.kernel.org, axboe@kernel.dk,
	boaz@plexistor.com, david@fromorbit.com,
	linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	arnd@arndb.de, ross.zwisler@linux.intel.com,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	benh@kernel.crashing.org, linux-nvdimm@lists.01.org,
	heiko.carstens@de.ibm.com, hch@lst.de, tj@kernel.org,
	paulus@samba.org, hpa@zytor.com, schwidefsky@de.ibm.com,
	willy@linux.intel.com, akpm@linux-foundation.org,
	torvalds@linux-foundation.org, mingo@kernel.org
Subject: Re: [PATCH v4 9/9] x86: convert dma_map_ops to support mapping a __pfn_t.
Date: Tue, 9 Jun 2015 08:58:54 +0200	[thread overview]
Message-ID: <20150609065854.GD10167@lst.de> (raw)
In-Reply-To: <20150605211955.20751.15047.stgit@dwillia2-desk3.amr.corp.intel.com>

On Fri, Jun 05, 2015 at 05:19:55PM -0400, Dan Williams wrote:
> As long as a dma_map_sg() implementation avoids sg_page() conversions it
> can support scatterlists that carry "page-less" __pfn_t entries.
> However, a couple implementations require that __pfn_t_has_page() is
> always true. The Xen swiotlb implementation's entanglements with ARM and
> the Calgary MMUs requirement to have a pre-existing virtual mapping make
> them unable to support this conversion (i.e. these now have 'depends on
> !HAVE_DMA_PFN').

That's why we really need a whole kernel conversion and not just a piecemail
one.  Given how trivial this patch is that doesn't look like a too big
task ayway.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-kernel@vger.kernel.org, axboe@kernel.dk,
	boaz@plexistor.com, david@fromorbit.com,
	linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	arnd@arndb.de, ross.zwisler@linux.intel.com,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	benh@kernel.crashing.org, linux-nvdimm@ml01.01.org,
	heiko.carstens@de.ibm.com, hch@lst.de, tj@kernel.org,
	paulus@samba.org, hpa@zytor.com, schwidefsky@de.ibm.com,
	willy@linux.intel.com, akpm@linux-foundation.org,
	torvalds@linux-foundation.org, mingo@kernel.org
Subject: Re: [PATCH v4 9/9] x86: convert dma_map_ops to support mapping a __pfn_t.
Date: Tue, 9 Jun 2015 08:58:54 +0200	[thread overview]
Message-ID: <20150609065854.GD10167@lst.de> (raw)
In-Reply-To: <20150605211955.20751.15047.stgit@dwillia2-desk3.amr.corp.intel.com>

On Fri, Jun 05, 2015 at 05:19:55PM -0400, Dan Williams wrote:
> As long as a dma_map_sg() implementation avoids sg_page() conversions it
> can support scatterlists that carry "page-less" __pfn_t entries.
> However, a couple implementations require that __pfn_t_has_page() is
> always true. The Xen swiotlb implementation's entanglements with ARM and
> the Calgary MMUs requirement to have a pre-existing virtual mapping make
> them unable to support this conversion (i.e. these now have 'depends on
> !HAVE_DMA_PFN').

That's why we really need a whole kernel conversion and not just a piecemail
one.  Given how trivial this patch is that doesn't look like a too big
task ayway.

  reply	other threads:[~2015-06-09  6:58 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-05 21:19 [PATCH v4 0/9] introduce __pfn_t, evacuate struct page from sgls Dan Williams
2015-06-05 21:19 ` Dan Williams
2015-06-05 21:19 ` [PATCH v4 1/9] introduce __pfn_t for scatterlists and pmem Dan Williams
2015-06-05 21:19   ` Dan Williams
2015-06-05 21:37   ` Linus Torvalds
2015-06-05 21:37     ` Linus Torvalds
2015-06-05 22:12     ` Dan Williams
2015-06-05 22:12       ` Dan Williams
2015-06-05 21:19 ` [PATCH v4 2/9] x86: support kmap_atomic_pfn_t() for persistent memory Dan Williams
2015-06-05 21:19   ` Dan Williams
2015-06-09  6:50   ` Christoph Hellwig
2015-06-09  6:50     ` Christoph Hellwig
2015-06-10 12:12   ` Christoph Hellwig
2015-06-10 12:12     ` Christoph Hellwig
2015-06-10 15:03     ` Matthew Wilcox
2015-06-10 15:03       ` Matthew Wilcox
2015-06-10 15:11       ` Christoph Hellwig
2015-06-10 15:11         ` Christoph Hellwig
2015-06-10 15:36         ` Dan Williams
2015-06-10 15:36           ` Dan Williams
2015-06-10 16:11           ` Christoph Hellwig
2015-06-10 16:11             ` Christoph Hellwig
2015-06-10 16:17             ` Dan Williams
2015-06-10 16:17               ` Dan Williams
2015-06-05 21:19 ` [PATCH v4 3/9] dax: drop size parameter to ->direct_access() Dan Williams
2015-06-05 21:19   ` Dan Williams
2015-06-06 11:37   ` Matthew Wilcox
2015-06-06 11:37     ` Matthew Wilcox
2015-06-09  6:51   ` Christoph Hellwig
2015-06-09  6:51     ` Christoph Hellwig
2015-06-05 21:19 ` [PATCH v4 4/9] dax: fix mapping lifetime handling, convert to __pfn_t + kmap_atomic_pfn_t() Dan Williams
2015-06-05 21:19   ` Dan Williams
2015-06-06 11:58   ` Matthew Wilcox
2015-06-06 11:58     ` Matthew Wilcox
2015-08-07 23:54     ` Dan Williams
2015-08-07 23:54       ` Dan Williams
2015-06-08 16:29   ` Elliott, Robert (Server Storage)
2015-06-08 16:29     ` Elliott, Robert (Server Storage)
2015-06-08 16:36     ` Dan Williams
2015-06-08 16:36       ` Dan Williams
2015-06-09  6:55   ` Christoph Hellwig
2015-06-09  6:55     ` Christoph Hellwig
2015-06-05 21:19 ` [PATCH v4 5/9] dma-mapping: allow archs to optionally specify a ->map_pfn() operation Dan Williams
2015-06-05 21:19   ` Dan Williams
2015-06-05 21:19 ` [PATCH v4 6/9] scatterlist: use sg_phys() Dan Williams
2015-06-05 21:19   ` Dan Williams
2015-06-09  6:59   ` Christoph Hellwig
2015-06-09  6:59     ` Christoph Hellwig
2015-06-05 21:19 ` [PATCH v4 7/9] scatterlist: cleanup sg_chain() and sg_unmark_end() Dan Williams
2015-06-05 21:19   ` Dan Williams
2015-06-05 21:19 ` [PATCH v4 8/9] scatterlist: convert to __pfn_t Dan Williams
2015-06-05 21:19   ` Dan Williams
2015-06-05 21:19 ` [PATCH v4 9/9] x86: convert dma_map_ops to support mapping a __pfn_t Dan Williams
2015-06-05 21:19   ` Dan Williams
2015-06-09  6:58   ` Christoph Hellwig [this message]
2015-06-09  6:58     ` Christoph Hellwig
2015-06-09 13:47     ` Konrad Rzeszutek Wilk
2015-06-05 21:23 ` [PATCH v4 0/9] introduce __pfn_t, evacuate struct page from sgls Dan Williams
2015-06-05 21:23   ` Dan Williams

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