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

["Michael S. Tsirkin" <mst@xxxxxxxxxxxxxx>]

Quoting r. Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>:
> Subject: RE: [Xen-devel] Userspace PIO access under xen
> 
>  
> 
> > The following simple program (below) mmaps PCI I/O memory 
> > into userspace. This works fine under linux, but not in Xen dom0.
> > 
> > Linux:
> > 
> > # ./test1 /sys/bus/pci/devices/0000\:07\:00.0/resource0 0 0 0
> > 
> > Xen dom0:
> > 
> > # ./test1 /sys/bus/pci/devices/0000\:07\:00.0/resource0 0 0 0xf000eef3
> 
> 
> Interesting -- I didn't know you could use /sys/bus/pci/devices/ for
> mapping memory.

You can also use /proc/bus/pci/ for this, the difference is that
you have to give full bus address to /proc/bus/pci/ , while
/sys/bus/pci/devices/ needs an offset within the resource.

> Change pci_mmap_page_range in arch/xen/arch/pci/i386.c to use
> io_remap_pfn_range

I've written a small kernel module to map PIO to userspace
using remap_page_range, and that doesnt seem to work, either.

> 
> I'll check something in.
> 
> Ian
> 

OK, let me know.

-- 
MST

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