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Message-Id: <20080919212327Y.fujita.tomonori@lab.ntt.co.jp> Date: Fri, 19 Sep 2008 21:24:18 +0900 From: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp> To: joerg.roedel@....com Cc: fujita.tomonori@....ntt.co.jp, mingo@...e.hu, linux-kernel@...r.kernel.org Subject: Re: [GIT PULL] AMD IOMMU updates for 2.6.28 On Fri, 19 Sep 2008 13:52:59 +0200 Joerg Roedel <joerg.roedel@....com> wrote: > On Fri, Sep 19, 2008 at 08:47:54PM +0900, FUJITA Tomonori wrote: > > On Fri, 19 Sep 2008 20:23:50 +0900 > > FUJITA Tomonori <fujita.tomonori@....ntt.co.jp> wrote: > > > > > On Fri, 19 Sep 2008 13:02:40 +0200 > > > Joerg Roedel <joerg.roedel@....com> wrote: > > > > > > > On Fri, Sep 19, 2008 at 07:51:11PM +0900, FUJITA Tomonori wrote: > > > > > On Fri, 19 Sep 2008 12:39:23 +0200 > > > > > Joerg Roedel <joerg.roedel@....com> wrote: > > > > > > > > > > > On Fri, Sep 19, 2008 at 07:28:13PM +0900, FUJITA Tomonori wrote: > > > > > > > On Fri, 19 Sep 2008 12:07:11 +0200 > > > > > > > Joerg Roedel <joerg.roedel@....com> wrote: > > > > > > > > > > > > > > > Hi Ingo, > > > > > > > > > > > > > > > > please pull the updates for the AMD IOMMU driver for the 2.6.28 merge > > > > > > > > window. Most of the patches had been sent to LKML for review and got > > > > > > > > comments. One patch touches the GART driver and was added after an > > > > > > > > objection with a patch previously in this series. Please pull. > > > > > > > > > > > > > > > > The following changes since commit 74546a8cd9a4e2c26a15a534f0be2f9cc08ae675: > > > > > > > > Ingo Molnar (1): > > > > > > > > Revert "fix warning in: "x86: HPET_MSI Initialise per-cpu HPET timers"" > > > > > > > > > > > > > > > > are available in the git repository at: > > > > > > > > > > > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/joro/linux-2.6-iommu.git iommu-updates-2.6.28 > > > > > > > > > > > > > > > > FUJITA Tomonori (1): > > > > > > > > AMD IOMMU: avoid unnecessary low zone allocation in alloc_coherent > > > > > > > > > > > > > > > > Joerg Roedel (24): > > > > > > > > AMD IOMMU: check for invalid device pointers > > > > > > > > AMD IOMMU: move TLB flushing to the map/unmap helper functions > > > > > > > > x86: move GART TLB flushing options to generic code > > > > > > > > > > > > > > As I wrote, I don't think that this GART patch is the right approach. > > > > > > > > > > > > I don't thinks its clean to leave nofullflush in GART code and move > > > > > > fullflush to generic code only. > > > > > > > > > > It's not clean for GART but clean for other IOMMUs. > > > > > > > > So its unclean anyway. It doesn't matter if for GART or for AMD IOMMU. > > > > > > > > > > If we move something then both. But feel > > > > > > free to submit a patch that removes the nofullflush option. I would not > > > > > > disagree with that. > > > > > > > > > > I'm not sure we can remove an option that we added. If we can, please > > > > > remove it now. There is no point to make the meaningless option > > > > > generic. > > > > > > > > I don't added this option. I just moved it to generic code from the > > > > > > You added it to the generic place. Moving it to the generic place > > > means adding it to the generic place. > > > > > > There is no difference in the end. Now 'nofullflush' is listed as the > > > generic place. > > > > > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > > > index c2e00ee..569527e 100644 > > > --- a/Documentation/kernel-parameters.txt > > > +++ b/Documentation/kernel-parameters.txt > > > @@ -888,6 +888,10 @@ and is between 256 and 4096 characters. It is defined in the file > > > nomerge > > > forcesac > > > soft > > > + fullflush > > > + Flush IO/TLB at every deallocation > > > + nofullflush > > > + Flush IO/TLB only when addresses are reused (default) > > > > And you don't need to add 'fullflush' to the generic place too. > > > > 'fullflush' will be supported with only GART and AMD IOMMU. So adding > > the description of it to both GART and AMD IOMMU should be fine. > > > > 'fullflush' has the same meaning for both IOMMUs. That's nice > > consistency, I think. > > Huh? The whole point of this patch was to have a common option between > IOMMUs to disable lazy IOTLB flushing. This was suggested by _you_ and > the only reason I wrote this patch. You misunderstand what I meant. I'm sorry if my explanation is not clear. > After this patch we can change other IOMMU implementations with lazy > flushing to use that parameter too. I'm not sure that Calgary wants to support such option. It always uses lazy flushing. What I don't like is that there is no consistency about the option name for lazy flushing. It doesn't mean that we move the option to the generic place. Here's my first reply: = Would it be nice to have consistency of IOMMU parameters? VT-d also has the kernel-boot option for this lazy flushing trick though VT-d 'strict' option is more vague than 'unmap_flush' = What I meant that using the option name 'strict' that VT-d uses for lazy flushing for AMD IOMMU would be better than introducing a new option name, "unmap_flush" for AMD IOMMU though I don't think that 'strict' is the good name. Seems 'fullflush' is better than 'strict'. So I think that it's better to use 'fullflush' for AMD IMMU rather introducing a new name, 'unmap_flush'. But again, it doesn't mean that 'fullflush' moves to the generic place. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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