On Mon, 13 Jul 2009 13:20:22 +0900 FUJITA Tomonori <fujita.tomon...@lab.ntt.co.jp> wrote:
> On Fri, 10 Jul 2009 16:12:48 +0200 > Ingo Molnar <mi...@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. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
