RE: [Xen-devel] [PATCH] Enable K8 GART as an IOMMU

["Langsdorf, Mark" <mark.langsdorf@xxxxxxx>]

> >--- a/linux-2.6-xen-sparse/arch/i386/mm/hypervisor.c Fri Feb 
> 09 10:48:41 2007 +0000
> >+++ b/linux-2.6-xen-sparse/arch/i386/mm/hypervisor.c Fri Feb 
> 09 16:32:04 2007 -0600
> >@@ -252,7 +252,7 @@ static void contiguous_bitmap_clear(
> > }
> > 
> > /* Protected by balloon_lock. */
> >-#define MAX_CONTIG_ORDER 9 /* 2MB */
> >+#define MAX_CONTIG_ORDER 16 /* 256MB */
> > static unsigned long discontig_frames[1<<MAX_CONTIG_ORDER];
> > static multicall_entry_t cr_mcl[1<<MAX_CONTIG_ORDER];
> 
> This seems dangerous to me.

We need at least 64MB of contiguous memory for the aperture.


> a/linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/dma-ma
> pping.h       Fri Feb 09 10:48:41 2007 +0000
> >+++ 
> b/linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/dma-ma
> pping.h       Fri Feb 09 16:32:04 2007 -0600
> >@@ -62,7 +62,12 @@ static inline int valid_dma_direction(in
> >             (dma_direction == DMA_FROM_DEVICE));
> > }
> > 
> >-#if 0
> >+#ifdef CONFIG_XEN
> >+#define global_need_iommu() 1
> >+#else
> >+#define global_need_iommu() 
> (HYPERVISOR_memory_op(XENMEM_maximum_ram_page, NULL)>MAX_DMA32_PFN)
> >+#endif
> >+
> > static inline int dma_mapping_error(dma_addr_t dma_addr)
> > {
> >     if (dma_ops->mapping_error)
> 
> HYPERVISOR_memory_op() if CONFIG_XEN is undefined?

Will fix.

> >--- a/linux-2.6-xen-sparse/lib/Makefile      Fri Feb 09 
> 10:48:41 2007 +0000
> >+++ b/linux-2.6-xen-sparse/lib/Makefile      Fri Feb 09 
> 16:32:04 2007 -0600
> >@@ -51,8 +51,7 @@ obj-$(CONFIG_SMP) += percpu_counter.o
> > obj-$(CONFIG_SMP) += percpu_counter.o
> > obj-$(CONFIG_AUDIT_GENERIC) += audit.o
> > 
> >-obj-$(CONFIG_SWIOTLB) += swiotlb.o
> >-swiotlb-$(CONFIG_XEN) := ../arch/i386/kernel/swiotlb.o
> >+obj-$(CONFIG_SWIOTLB) += swiotlb-xen.o
> > 
> > hostprogs-y := gen_crc32table
> > clean-files := crc32table.h
> 
> This seems very unlikely to have been tested in a native 
> build. You should use cherry-pick-xen in the file.

Okay.

> I generally welcome moving arch/i386/kernel/swiotlb.c to 
> lib/swiotlb-xen.c, but would appreciate if you then also
> removed the original file (and perhaps this should be done
> as a separate patch, so that it'd be clear that the move
> itself doesn't change the file in any way (and if you need 
> changes to it for the IOMMU patch, have only those changes
> in the patch here).

I'll seperate the reorg a bit and make it clearer.  Thanks for
looking at this.

-Mark Langsdorf
AMD, Inc.



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