On Mon, 1 Jun 2009 10:22:59 +0100 Russell King <rmk+lkml@xxxxxxxxxxxxxxxx> wrote: > On Mon, Jun 01, 2009 at 06:16:56PM +0900, FUJITA Tomonori wrote: > > On Mon, 1 Jun 2009 09:29:43 +0100 > > Russell King <rmk+lkml@xxxxxxxxxxxxxxxx> wrote: > > > > > On Mon, Jun 01, 2009 at 05:08:09PM +0900, FUJITA Tomonori wrote: > > > > This adds a version of the dma-mapping API to asm-generic that can be > > > > used by most architectures that only need a linear mapping. > > > > > > It depends what is meant by "linear mapping". > > > > > > If that's just a way of saying "all that needs to be done for the > > > DMA streaming APIs is to flush the cache" then the vast majority of > > > ARMs fall into that category. > > > > I guess that his definition is 'no dynamic remapping'. > > ... which as I say is what ARM does for the streaming mappings. Ok, then we agree. > > > The DMA bounce code is a broken design concept that really needs to > > > be put to death. > > > > You are talking about arch/arm/common/dmabounce.c? If so, it sounds > > more interesting (to me at least). It's kinda swiotlb per device, > > right? What you want to do for arch/arm/common/dmabounce.c? > > Yes. > > It's a nasty hack which leads to OOMs on various platforms since it > causes additional memory pressure from parts of the kernel which we > don't expect, and also causes additional difficulty with allocating > and freeing DMA memory from IRQ context. There's an unsolved bug in > the kernel bugzilla for this which I see no hope of ever being resolved. > > I _really_ wish that dmabounce never existed. It's a right royal > pain in the preverbial. Can ARM replace the dmabounce with swiotlb? -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
