RE: [Xen-devel] Userspace PIO access under xen

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> > You have to use io_remap_pfn_range for mapping IO space. Using 
> > remap_pfn_range is technically a bug in the i386 code.
> 
> #define io_remap_page_range(vma, vaddr, paddr, size, prot) \
>                 remap_pfn_range(vma, vaddr, (paddr) >> 
> PAGE_SHIFT, size, prot)
> 
> So I just tested again and of course io_remap_pfn_range gives 
> the same result.
> 
> > I believe the pfn_range functions are preferred over page_range 
> > functions anyhow.
> 
> I actually use remap_pfn_range, I mistyped that.

Look at arch/xen/kernel/devmem.c and include/asm-xen/asm-i386/pgtable.h

#define io_remap_page_range(vma,from,phys,size,prot) \
direct_remap_area_pages(vma->vm_mm,from,phys,size,prot,DOMID_IO)

It works fine for /dev/mem. It's possible there's a definition missing
for io_remap_pfn_range.

Ian

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