On Wednesday 23 March 2011 20:12:53 Mark Salter wrote: > I'm working with a new architecture port (nommu) and was wanting to use > the generic page.h but there is a problem. I'm using CONFIG_FLATMEM with > a non-zero CONFIG_KERNEL_RAM_BASE_ADDRESS. The hardware uses this same > address to access RAM from code and for DMA purposes. The generic page.h > has: > > #ifdef CONFIG_KERNEL_RAM_BASE_ADDRESS > #define PAGE_OFFSET (CONFIG_KERNEL_RAM_BASE_ADDRESS) > #else > #define PAGE_OFFSET (0) > #endif > > #ifndef __ASSEMBLY__ > > #define __va(x) ((void *)((unsigned long)(x) + PAGE_OFFSET)) > #define __pa(x) ((unsigned long) (x) - PAGE_OFFSET) > > The problem I have is that __va(x) and __pa(x) should do nothing on > this architecture. If I use the following, then everything seems to > work as it should. > > > diff --git a/include/asm-generic/page.h b/include/asm-generic/page.h > index 75fec18..4dc4a81 100644 > --- a/include/asm-generic/page.h > +++ b/include/asm-generic/page.h > @@ -73,8 +73,8 @@ extern unsigned long memory_end; > > #ifndef __ASSEMBLY__ > > -#define __va(x) ((void *)((unsigned long)(x) + PAGE_OFFSET)) > -#define __pa(x) ((unsigned long) (x) - PAGE_OFFSET) > +#define __va(x) ((void *)((unsigned long) (x))) > +#define __pa(x) ((unsigned long) (x)) > > #define virt_to_pfn(kaddr) (__pa(kaddr) >> PAGE_SHIFT) > #define pfn_to_virt(pfn) __va((pfn) << PAGE_SHIFT) > > > Am I missing something here? The only other arch using the generic > page.h is blackfin, but it uses a zero PAGE_OFFSET, so my patch > would have no effect there. I don't think the handling of nonzero PAGE_OFFSET in asm-generic/page.h was intentional. When Remis worked on the patch to introduce this file, the idea was to take the common parts from all related architectures and come up with a way that works on most of them. Maybe one of the other arch maintainers has an opinion on this. If not, I don't mind your patch, just add that to your series when submitting the architecture for review. Arnd -- 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
