On Wed, Jul 14, 2010 at 10:59:38AM +0900, FUJITA Tomonori wrote: > On Tue, 13 Jul 2010 05:14:21 -0700 > Zach Pfeffer <zpfeffer@xxxxxxxxxxxxxx> wrote: > > > > You mean that you want to specify this alignment attribute every time > > > you create an IOMMU mapping? Then you can set segment_boundary_mask > > > every time you create an IOMMU mapping. It's odd but it should work. > > > > Kinda. I want to forget about IOMMUs, devices and CPUs. I just want to > > create a mapping that has the alignment I specify, regardless of the > > mapper. The mapping is created on a VCM and the VCM is associated with > > a mapper: a CPU, an IOMMU'd device or a direct mapped device. > > Sounds like you can do the above with the combination of the current > APIs, create a virtual address and then an I/O address. > Yes, and that's what the implementation does - and all the other implementations that need to do this same thing. Why not solve the problem once? > The above can't be a reason to add a new infrastructure includes more > than 3,000 lines. Right now its 3000 lines because I haven't converted to a function pointer based implementation. Once I do that the size of the implementation will shrink and the code will act as a lib. Users pass buffer mappers and the lib will ease the management of of those buffers. > > > > > Another possible solution is extending struct dma_attrs. We could add > > > the alignment attribute to it. > > > > That may be useful, but in the current DMA-API may be seen as > > redundant info. > > If there is real requirement, we can extend the DMA-API. If the DMA-API contained functions to allocate virtual space separate from physical space and reworked how chained buffers functioned it would probably work - but then things start to look like the VCM API which does graph based map management. > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxxx For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
