ia64: make IOMMU respect the segment boundary limits

This patch is another sequel to my patchset that fixes iommu segment boundary problems, that is, IOMMUs allocate memory areas without considering a low level driver's segment boundary limits:

http://www.mail-archive.com/[email protected]/msg11919.html

This patchset fixes the IA64 IOMMU code.

This assumes that ioc->ibase is on iovp_size boundary. If not, please let me know. I'll fix the patch.

From: FUJITA Tomonori <[email protected]>
Subject: [PATCH -mm] ia64: make IOMMU respect the segment boundary limits

This makes IA64's IOMMU implementation not allocate a memory area spanning LLD's segment boundary.

---
 arch/ia64/Kconfig               |    3 ++
 arch/ia64/hp/common/sba_iommu.c |   56 +++++++++++++++++++++++++++------------
 2 files changed, 42 insertions(+), 17 deletions(-)

index 8fa3faf..1b73ffe 100644
@@ -611,6 +611,9 @@ config IRQ_PER_CPU
 	bool
 	default y
 
+config IOMMU_HELPER
+	def_bool (IA64_HP_ZX1 || IA64_HP_ZX1_SWIOTLB || IA64_GENERIC)
+
 source "arch/ia64/hp/sim/Kconfig"
 
 source "arch/ia64/Kconfig.debug"

1.5.3.7

Please make this easier.

afacit the patches to which you refer are already in mainline, so this is *not* a "-mm" patch. It is needed in mainline, correct?

And if it fixes a bug then it is needed in 2.6.25.

Is that correct?

Who is the person who who knows the answer to this?

Does this mean that the patch wasn't runtime tested? If so, how do you know there is a bug?

This changelog doesn't actually tell us that this patch fixed a bug.

It should tell us what the bug is, and how it fixed it, please.

Very sorry,

It's not needed immediately. Please apply it to -mm.

No, it isn't needed in 2.6.25. Sorry, I shouldn't have used 'fixes'.

IOMMUs allocate memory areas without considering a low level driver's segment boundary limits. Thus low level drivers have a workaround to adjust scatter lists that IOMMUs build. Duplicating such workaround in many LLDs and adjusting scatter lists in LLDs again are not good (because they easily lead to bugs especially after sg chain introduction and not efficient, etc).

I've been modifying some of the IOMMUs to make them respect low level drivers' limits.

I expected that someone in IA64 list might konw the answer. I put BUG_ON so we will know the answer eventually even if nobody knows it.

Sorry, I don't have IA64. So it's not tested. I read the code and I learned that IA64's IOMMU ignores segment boundary limits.

I want the patch to be tested in -mm kernels and hope that it will be merged into 2.6.26.

How about the following description?

IA64's IOMMU implementation allocates memory areas spanning LLD's segment boundary limit. It forces low level drivers to have a workaround to adjust scatter lists that the IOMMU builds.

We are in the process of making all the IOMMUs respect the segment boundary limits to remove such work around in LLDs. This patch is for IA64's IOMMU.

Thanks,