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From: Christoph Hellwig <hch@lst.de>
To: Dongli Zhang <dongli.zhang@oracle.com>
Cc: dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org,
	iommu@lists.linux-foundation.org, linux-mips@vger.kernel.org,
	linux-mmc@vger.kernel.org, linux-pci@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org, nouveau@lists.freedesktop.org,
	x86@kernel.org, xen-devel@lists.xenproject.org,
	linux-kernel@vger.kernel.org, adrian.hunter@intel.com,
	akpm@linux-foundation.org, benh@kernel.crashing.org,
	bskeggs@redhat.com, bhelgaas@google.com, bp@alien8.de,
	boris.ostrovsky@oracle.com, hch@lst.de, chris@chris-wilson.co.uk,
	daniel@ffwll.ch, airlied@linux.ie, hpa@zytor.com,
	mingo@kernel.org, mingo@redhat.com, jani.nikula@linux.intel.com,
	joonas.lahtinen@linux.intel.com, jgross@suse.com,
	konrad.wilk@oracle.com, m.szyprowski@samsung.com,
	matthew.auld@intel.com, mpe@ellerman.id.au, rppt@kernel.org,
	paulus@samba.org, peterz@infradead.org, robin.murphy@arm.com,
	rodrigo.vivi@intel.com, sstabellini@kernel.org,
	bauerman@linux.ibm.com, tsbogend@alpha.franken.de,
	tglx@linutronix.de, ulf.hansson@linaro.org, joe.jin@oracle.com,
	thomas.lendacky@amd.com
Subject: Re: [PATCH RFC v1 5/6] xen-swiotlb: convert variables to arrays
Date: Thu, 4 Feb 2021 09:40:23 +0100	[thread overview]
Message-ID: <20210204084023.GA32328@lst.de> (raw)
In-Reply-To: <20210203233709.19819-6-dongli.zhang@oracle.com>

So one thing that has been on my mind for a while:  I'd really like
to kill the separate dma ops in Xen swiotlb.  If we compare xen-swiotlb
to swiotlb the main difference seems to be:

 - additional reasons to bounce I/O vs the plain DMA capable
 - the possibility to do a hypercall on arm/arm64
 - an extra translation layer before doing the phys_to_dma and vice
   versa
 - an special memory allocator

I wonder if inbetween a few jump labels or other no overhead enablement
options and possibly better use of the dma_range_map we could kill
off most of swiotlb-xen instead of maintaining all this code duplication?

  reply	other threads:[~2021-02-04  8:41 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-03 23:37 [PATCH RFC v1 0/6] swiotlb: 64-bit DMA buffer Dongli Zhang
2021-02-03 23:37 ` [PATCH RFC v1 1/6] swiotlb: define new enumerated type Dongli Zhang
2021-02-03 23:37 ` [PATCH RFC v1 2/6] swiotlb: convert variables to arrays Dongli Zhang
2021-02-04  7:29   ` Christoph Hellwig
2021-02-04 11:49     ` Robin Murphy
2021-02-04 19:31       ` Konrad Rzeszutek Wilk
2021-02-03 23:37 ` [PATCH RFC v1 3/6] swiotlb: introduce swiotlb_get_type() to calculate swiotlb buffer type Dongli Zhang
2021-02-03 23:37 ` [PATCH RFC v1 4/6] swiotlb: enable 64-bit swiotlb Dongli Zhang
2021-02-03 23:37 ` [PATCH RFC v1 5/6] xen-swiotlb: convert variables to arrays Dongli Zhang
2021-02-04  8:40   ` Christoph Hellwig [this message]
2021-02-07 15:56     ` Christoph Hellwig
2021-02-19 20:32       ` Konrad Rzeszutek Wilk
2021-02-19 23:59         ` Boris Ostrovsky
2021-02-23  1:22         ` Stefano Stabellini
2021-02-03 23:37 ` [PATCH RFC v1 6/6] xen-swiotlb: enable 64-bit xen-swiotlb Dongli Zhang

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