From: Christoph Hellwig <hch@lst.de>
To: Russell King - ARM Linux <linux@armlinux.org.uk>
Cc: linux-mips@linux-mips.org,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
linux-pci@vger.kernel.org, x86@kernel.org,
linux-block@vger.kernel.org, linux-mm@kvack.org,
iommu@lists.linux-foundation.org, sparclinux@vger.kernel.org,
Christoph Hellwig <hch@lst.de>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 11/12] swiotlb: move the SWIOTLB config symbol to lib/Kconfig
Date: Tue, 24 Apr 2018 08:55:49 +0200 [thread overview]
Message-ID: <20180424065549.GA18468@lst.de> (raw)
In-Reply-To: <20180423235205.GH16141@n2100.armlinux.org.uk>
On Tue, Apr 24, 2018 at 12:52:05AM +0100, Russell King - ARM Linux wrote:
> On Mon, Apr 23, 2018 at 07:04:18PM +0200, Christoph Hellwig wrote:
> > This way we have one central definition of it, and user can select it as
> > needed. Note that we also add a second ARCH_HAS_SWIOTLB symbol to
> > indicate the architecture supports swiotlb at all, so that we can still
> > make the usage optional for a few architectures that want this feature
> > to be user selectable.
> >
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
>
> Hmm, this looks like we end up with NEED_SG_DMA_LENGTH=y on ARM by
> default, which probably isn't a good idea - ARM pre-dates the dma_length
> parameter in scatterlists, and I don't think all code is guaranteed to
> do the right thing if this is enabled.
We shouldn't end up with NEED_SG_DMA_LENGTH=y on ARM by default.
It is only select by ARM_DMA_USE_IOMMU before the patch, and it will
now also be selected by SWIOTLB, which for arm is never used or seleted
directly by anything but xen-swiotlb.
Then again looking at the series there shouldn't be any need to
even select NEED_SG_DMA_LENGTH for swiotlb, as we'll never merge segments,
so I'll fix that up.
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next prev parent reply other threads:[~2018-04-24 6:55 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-23 17:04 centralize SWIOTLB config symbol and misc other cleanups V2 Christoph Hellwig
2018-04-23 17:04 ` [PATCH 01/12] iommu-common: move to arch/sparc Christoph Hellwig
2018-04-23 17:04 ` [PATCH 02/12] iommu-helper: unexport iommu_area_alloc Christoph Hellwig
2018-04-23 17:04 ` [PATCH 03/12] iommu-helper: mark iommu_is_span_boundary as inline Christoph Hellwig
2018-04-23 17:04 ` [PATCH 04/12] iommu-helper: move the IOMMU_HELPER config symbol to lib/ Christoph Hellwig
2018-04-23 17:04 ` [PATCH 05/12] scatterlist: move the NEED_SG_DMA_LENGTH config symbol to lib/Kconfig Christoph Hellwig
2018-04-23 17:04 ` [PATCH 06/12] dma-mapping: move the NEED_DMA_MAP_STATE " Christoph Hellwig
2018-04-23 17:04 ` [PATCH 07/12] arch: remove the ARCH_PHYS_ADDR_T_64BIT config symbol Christoph Hellwig
2018-04-23 17:04 ` [PATCH 08/12] arch: define the ARCH_DMA_ADDR_T_64BIT config symbol in lib/Kconfig Christoph Hellwig
2018-04-23 17:04 ` [PATCH 09/12] PCI: remove CONFIG_PCI_BUS_ADDR_T_64BIT Christoph Hellwig
2018-04-23 17:04 ` [PATCH 10/12] arm: don't build swiotlb by default Christoph Hellwig
2018-04-23 20:09 ` Konrad Rzeszutek Wilk
2018-04-23 17:04 ` [PATCH 11/12] swiotlb: move the SWIOTLB config symbol to lib/Kconfig Christoph Hellwig
2018-04-23 20:11 ` Konrad Rzeszutek Wilk
2018-04-23 23:52 ` Russell King - ARM Linux
2018-04-24 6:55 ` Christoph Hellwig [this message]
2018-04-24 7:47 ` Russell King - ARM Linux
2018-04-24 7:56 ` Christoph Hellwig
2018-04-23 17:04 ` [PATCH 12/12] swiotlb: remove the CONFIG_DMA_DIRECT_OPS ifdefs Christoph Hellwig
-- strict thread matches above, loose matches on Subject: below --
2018-04-15 14:59 centralize SWIOTLB config symbol and misc other cleanups Christoph Hellwig
2018-04-15 14:59 ` [PATCH 11/12] swiotlb: move the SWIOTLB config symbol to lib/Kconfig Christoph Hellwig
2018-04-17 6:10 ` Anshuman Khandual
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