Re: [Xen-devel] x86_64 eth0 e1000_clean_tx_irq tx hang

[Chris Wright <chrisw@xxxxxxxxxxxx>]

* Kamble, Nitin A (nitin.a.kamble@xxxxxxxxx) wrote:
> >  - limiting to 2G works fine, sounds like something with swiotlb
> 
> I noticed it too and exactly same. I also notice this in the dom0 dmesg.

After spending hours trying to find something -- anything -- wrong with
irq delivery and e1000 hung tx unit, I went back to my original hunch,
which was swiotlb related.  When TSO is enabled, some debugging showed
this:

swiotlb_map_page: returns d586a000
dma_map_page: returns ffffffffd586a000

Indeed.

 a43:   e8 00 00 00 00          callq  a48 <dma_map_page+0xc8>        a44: 
R_X86_64_PC32      swiotlb_map_page+0xfffffffffffffffc
 a48:   48 63 d8                movslq %eax,%rbx

Whoops.  Prototype mismatch.

And had we been paying attention:

/home/chrisw/hg/xen/xen-unstable/linux-2.6.16-rc2-xen0/arch/x86_64/kernel/../../i386/kernel/pci-dma-xen.c:107:
 warning: implicit declaration of function âswiotlb_map_pageâ
/home/chrisw/hg/xen/xen-unstable/linux-2.6.16-rc2-xen0/arch/x86_64/kernel/../../i386/kernel/pci-dma-xen.c:
 In function âdma_unmap_pageâ:
/home/chrisw/hg/xen/xen-unstable/linux-2.6.16-rc2-xen0/arch/x86_64/kernel/../../i386/kernel/pci-dma-xen.c:125:
 warning: implicit declaration of function âswiotlb_unmap_pageâ

Here's a quick patch that fixes the issue (not ready to apply to
-unstable, since it's a file that's not in sparse tree).  Nitin, this
should fix your problem as well.  I'll work on a proper patch later this
evening or tomorrow morning.

thanks,
-chris
--

--- linux-2.6.16-rc2/include/asm-x86_64/swiotlb.h       2006-02-15 
21:42:24.000000000 -0500
+++ linux-2.6.16-rc2-xen0/include/asm-x86_64/swiotlb.h  2006-02-15 
21:19:15.000000000 -0500
@@ -38,6 +38,11 @@
 extern void swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sg,
                         int nents, int direction);
 extern int swiotlb_dma_mapping_error(dma_addr_t dma_addr);
+extern dma_addr_t swiotlb_map_page(struct device *hwdev, struct page *page,
+                                   unsigned long offset, size_t size,
+                                   enum dma_data_direction direction);
+extern void swiotlb_unmap_page(struct device *hwdev, dma_addr_t dma_address,
+                               size_t size, enum dma_data_direction direction);
 extern void swiotlb_free_coherent (struct device *hwdev, size_t size,
                                   void *vaddr, dma_addr_t dma_handle);
 extern int swiotlb_dma_supported(struct device *hwdev, u64 mask);

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