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From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
To: mingo@elte.hu
Cc: jeremy@goop.org, tony.luck@intel.com, linux-ia64@vger.kernel.org,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	Ian.Campbell@eu.citrix.com, linuxppc-dev@ozlabs.org,
	joerg.roedel@amd.com
Subject: Re: [00/15] swiotlb cleanup
Date: Mon, 13 Jul 2009 18:16:30 +0900	[thread overview]
Message-ID: <20090713181558B.fujita.tomonori@lab.ntt.co.jp> (raw)
In-Reply-To: <20090713131157V.fujita.tomonori@lab.ntt.co.jp>

On Mon, 13 Jul 2009 13:20:22 +0900
FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> wrote:

> On Fri, 10 Jul 2009 16:12:48 +0200
> Ingo Molnar <mingo@elte.hu> wrote:
> 
> > > functionality and reimplemented the surrounding infrastructure in 
> > > terms of that (and incorporating our additional requirements). I 
> > > prototyped this (it is currently unworking, in fact it seems to 
> > > have developed rather a taste for filesystems :-() but the 
> > > diffstat of my WIP patch is:
> > >
> > >          arch/x86/kernel/pci-swiotlb.c |    6 
> > >          arch/x86/xen/pci-swiotlb.c    |    2 
> > >          drivers/pci/xen-iommu.c       |  385 ++++++++++++++++++++++++++++++++++++++++--
> > >          include/linux/swiotlb.h       |   12 +
> > >          lib/swiotlb.c                 |   10 -
> > >          5 files changed, 385 insertions(+), 30 deletions(-)
> > >
> > > where a fair number of the lines in xen-iommu.c are copies of 
> > > functions from swiotlb.c with minor modifications. As I say it 
> > > doesn't work yet but I think it's roughly indicative of what such 
> > > an approach would look like. I don't like it much but am happy to 
> > > run with it if it looks to be the most acceptable approach. [...]
> > 
> > +400 lines of code to avoid much fewer lines of generic code impact 
> > on the lib/swiotlb.c side sounds like a bad technical choice to me. 
> 
> The amount of code is not the point. The way to impact on the
> lib/swiotlb.c is totally wrong from the perspective of the kernel
> design; it uses architecture code in the very original (xen) way.

btw, '+400 lines of code to avoid much fewer lines of generic code
impact on the lib/swiotlb.c' doesn't sound true to me.

Here is a patch in the way that Xen people want to do:

http://patchwork.kernel.org/patch/26343/

---
 arch/x86/Kconfig                 |    4 +
 arch/x86/include/asm/io.h        |    2 +
 arch/x86/include/asm/pci_x86.h   |    1 +
 arch/x86/include/asm/xen/iommu.h |   12 ++
 arch/x86/kernel/pci-dma.c        |    3 +
 arch/x86/pci/Makefile            |    1 +
 arch/x86/pci/init.c              |    6 +
 arch/x86/pci/xen.c               |   51 +++++++
 drivers/pci/Makefile             |    2 +
 drivers/pci/xen-iommu.c          |  271 ++++++++++++++++++++++++++++++++++++++


Even with the way that Xen people want to do, drivers/pci/xen-iommu.c
is about 300 lines. And my patchset removes the nice amount of lines
for dom0 support. I don't see much difference wrt lines.

  reply	other threads:[~2009-07-13  9:20 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-07-10  1:04 [00/15] swiotlb cleanup FUJITA Tomonori
2009-07-10  1:04 ` [PATCH 01/15] swiotlb: remove unused swiotlb_alloc_boot() FUJITA Tomonori
2009-07-10  1:04 ` [PATCH 02/15] swiotlb: remove unused swiotlb_alloc() FUJITA Tomonori
2009-07-10  1:04 ` [PATCH 03/15] swiotlb: remove swiotlb_arch_range_needs_mapping FUJITA Tomonori
2009-07-10  1:04 ` [PATCH 04/15] swiotlb: remove unnecessary swiotlb_bus_to_virt FUJITA Tomonori
2009-07-14  2:17   ` Becky Bruce
2009-07-14  5:08     ` FUJITA Tomonori
2009-07-16  3:40     ` Benjamin Herrenschmidt
2009-07-10  1:04 ` [PATCH 05/15] x86: add dma_capable() to replace is_buffer_dma_capable() FUJITA Tomonori
2009-07-10  1:04 ` [PATCH 06/15] x86: replace is_buffer_dma_capable() with dma_capable FUJITA Tomonori
2009-07-10  1:04 ` [PATCH 07/15] ia64: add dma_capable() to replace is_buffer_dma_capable() FUJITA Tomonori
2009-07-10  1:04 ` [PATCH 08/15] powerpc: " FUJITA Tomonori
2009-07-10  1:04 ` [PATCH 09/15] swiotlb: use dma_capable() FUJITA Tomonori
2009-07-10  1:04 ` [PATCH 10/15] powerpc: remove unncesary swiotlb_arch_address_needs_mapping FUJITA Tomonori
2009-07-10  1:05 ` [PATCH 11/15] remove is_buffer_dma_capable() FUJITA Tomonori
2009-07-10  1:05 ` [PATCH 12/15] x86, IA64, powerpc: add phys_to_dma() and dma_to_phys() FUJITA Tomonori
2009-07-10  1:05 ` [PATCH 13/15] swiotlb: use phys_to_dma and dma_to_phys FUJITA Tomonori
2009-07-10  1:05 ` [PATCH 14/15] powerpc: remove unused swiotlb_phys_to_bus() and swiotlb_bus_to_phys() FUJITA Tomonori
2009-07-10  1:05 ` [PATCH 15/15] x86: " FUJITA Tomonori
2009-07-10  5:12 ` [00/15] swiotlb cleanup Ingo Molnar
2009-07-10  5:35   ` FUJITA Tomonori
2009-07-10 14:02     ` Ian Campbell
2009-07-13  4:20       ` FUJITA Tomonori
2009-07-13  9:40         ` Ian Campbell
2009-07-13  9:53           ` FUJITA Tomonori
2009-07-13 10:05             ` Ian Campbell
2009-07-10 14:01   ` Ian Campbell
2009-07-10 14:12     ` Ingo Molnar
2009-07-13  4:20       ` FUJITA Tomonori
2009-07-13  9:16         ` FUJITA Tomonori [this message]
2009-07-18 10:41           ` Ingo Molnar
2009-07-14  3:13   ` Becky Bruce
2009-07-15 20:24     ` Becky Bruce

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