[PATCH] sparc32: fix iommu_flush_iotlb end address

[PATCH] sparc32: fix iommu_flush_iotlb end address

[Bob Breuer]

[-- Attachment #1: Type: text/plain, Size: 603 bytes --]

Fix the calculation of the end address when flushing iotlb entries to
ram.  This bug has been a cause of esp dma errors, and it affects
HyperSPARC systems much worse than SuperSPARC systems.

Signed-off-by: Bob Breuer <breuerr@mc.net>
---

Just in case it's not obvious from the patch as to how the dma was
broken:  Each dma mapping sets up iopte entries for the iommu, and the
iommu only looks in main memory for the iopte entries.  If there is a
group of iopte entries that are smaller than a page in size, but
straddle a page boundary, the broken code would fail to flush the last
page to ram.

Bob


[-- Attachment #2: sparc32-fix-flush_iotlb_end.patch.txt --]
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diff --git a/arch/sparc/mm/iommu.c b/arch/sparc/mm/iommu.c
index 77840c8..7215849 100644
--- a/arch/sparc/mm/iommu.c
+++ b/arch/sparc/mm/iommu.c
@@ -144,8 +144,9 @@ static void iommu_flush_iotlb(iopte_t *i
 	unsigned long start;
 	unsigned long end;
 
-	start = (unsigned long)iopte & PAGE_MASK;
+	start = (unsigned long)iopte;
 	end = PAGE_ALIGN(start + niopte*sizeof(iopte_t));
+	start &= PAGE_MASK;
 	if (viking_mxcc_present) {
 		while(start < end) {
 			viking_mxcc_flush_page(start);

Re: [PATCH] sparc32: fix iommu_flush_iotlb end address

[David Miller]

From: Bob Breuer <breuerr@mc.net>
Date: Mon, 19 Jun 2006 23:08:59 -0500

> Fix the calculation of the end address when flushing iotlb entries to
> ram.  This bug has been a cause of esp dma errors, and it affects
> HyperSPARC systems much worse than SuperSPARC systems.
> 
> Signed-off-by: Bob Breuer <breuerr@mc.net>

Good catch, that bug would explain a lot.

Applied, and I'll toss this to -stable too.

Re: [PATCH] sparc32: fix iommu_flush_iotlb end address

[Martin Habets]

Hi Bob,

On Mon, Jun 19, 2006 at 11:08:59PM -0500, Bob Breuer wrote:
> Fix the calculation of the end address when flushing iotlb entries to
> ram.  This bug has been a cause of esp dma errors, and it affects
> HyperSPARC systems much worse than SuperSPARC systems.

Thanks for this patch! I was going cross-eyed trying to figure this
out. I have updated kernel bug 6344 with this info. Can no longer reproduce
any esp dma errors.

Thanks,
-- 
Martin

Re: [PATCH] sparc32: fix iommu_flush_iotlb end address

[BERTRAND Joël]

Martin Habets a écrit :
> Hi Bob,
> 
> On Mon, Jun 19, 2006 at 11:08:59PM -0500, Bob Breuer wrote:
> 
>>Fix the calculation of the end address when flushing iotlb entries to
>>ram.  This bug has been a cause of esp dma errors, and it affects
>>HyperSPARC systems much worse than SuperSPARC systems.
> 
> 
> Thanks for this patch! I was going cross-eyed trying to figure this
> out. I have updated kernel bug 6344 with this info. Can no longer reproduce
> any esp dma errors.

	Thanks for this patch. I shall test it in smp configuration. Do you 
know the release of the official kernel that supports sparc32 smp mode ? 
I have tested the 2.6.17.1 kernel without success (ot doesn't build due 
to a undefined symbol...).

	Regards,

	JKB

Re: [PATCH] sparc32: fix iommu_flush_iotlb end address

[Bob Breuer]

BERTRAND Joël wrote:
>     Thanks for this patch. I shall test it in smp configuration. Do you
> know the release of the official kernel that supports sparc32 smp mode ?
> I have tested the 2.6.17.1 kernel without success (ot doesn't build due
> to a undefined symbol...).

For sparc32 smp without extra patches, 2.6.17.X won't work.  You will
need at least 2.6.17-git2 or newer.

Bob

Re: [PATCH] sparc32: fix iommu_flush_iotlb end address

[BERTRAND Joël]

	Hello,

	I have build a 2.6.17-git7. It can boot with init=/bin/bash but if I 
try to boot with init=2 (debian system), kernel craches when it tries to 
mount local filesystem (watchdog reset or dead lock).

	Configuration : 448 MB, 2*SM71, CG14, raid1.

	I will try a -git10...

	Regards,

	JKB