Re: [PATCH] alpha: compile fixes

[Ivan Kokshaysky <ink@jurassic.park.msu.ru>]

On Wed, Jan 28, 2009 at 11:53:45AM +0900, FUJITA Tomonori wrote:
> A patch to change Alpha to handle two dma mapping implementations
> (pci-noop and the IOMMU) in the standard way (like X86, POWER, IA64,
> etc do) is acceptable?
> 
> pci-noop has something like struct dma_map_ops nommu_dma_ops (similar
> to pci-nommu.c in arch/x86/kernel/pci-nommu.c) and pci_iommu.c has
> struct dma_map_ops iommu_dma_ops. Then at startup, the kernel properly
> sets dma_ops pointer to nommu_dma_ops or iommu_dma_ops.
> 
> Then we can handle the dma mapping operations in the consistent way,
> e.g., dma_map_sg can be just `return ops->map_sg(dev, sg, nents,
> dir)`.

I don't think that we need this. In GENERIC kernel, alpha dma-mapping
functions work universally, Jensen included. The only reason pci-noop.c
is there is an optimization for kernel built specifically for Jensen,
which is the only non-PCI alpha - we simply don't compile useless stuff in.

Ivan.