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SubjectRe: [RFC patch] init default dma_ops to prepare intel_iommu_init failure
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On Thu, 13 Aug 2009 13:48:45 +0800
Luming Yu <luming.yu@gmail.com> wrote:

> >>
> >> This check can not be removed. Otherwise, swiotlb_dma_ops will always override
> >> previous dma_ops value.
> >
> > Yeah.
>
> I think pci_swiotlb_init needs to be cleaned up for both x86_{32,64} and ia64.
> it should be used to init default dma_ops, and the call site of it should be
> as early as platform_dma_init in mem_init. SInce swiotlb_dma_ops is pitched as
> default dma_ops for x86, ia64, we really don't need to let pci_swiotlb_init
> know iommu_deteced, dmar_disabled or iommu_passthrough...and anything
> like that..
> Please note the major wrong assumption of the current implementation is
> "iommu_deteced == iommu working" that I was trying to fix.

How about this?

You can work around that assumption, I guess.


diff --git a/arch/ia64/kernel/pci-dma.c b/arch/ia64/kernel/pci-dma.c
index f6b1ff0..48caafa 100644
--- a/arch/ia64/kernel/pci-dma.c
+++ b/arch/ia64/kernel/pci-dma.c
@@ -20,6 +20,8 @@

#include <asm/page.h>

+extern int swiotlb_late_init_with_default_size (size_t size);
+
dma_addr_t bad_dma_address __read_mostly;
EXPORT_SYMBOL(bad_dma_address);

@@ -44,11 +46,25 @@ struct device fallback_dev = {
};

extern struct dma_map_ops intel_dma_ops;
+extern struct dma_map_ops swiotlb_dma_ops;

static int __init pci_iommu_init(void)
{
- if (iommu_detected)
- intel_iommu_init();
+ int ret;
+
+ if (iommu_detected) {
+ ret = intel_iommu_init();
+ if (ret) {
+#ifdef CONFIG_IA64_GENERIC
+ dma_ops = &swiotlb_dma_ops;
+ if (swiotlb_late_init_with_default_size(64 * (1<<20)))
+ panic("failed to initialize swiotlb");
+ machvec_init("dig");
+#else
+ panic("Unable to find Intel IOMMU");
+#endif
+ }
+ }

return 0;
}

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