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

To: "Michael S. Tsirkin" <mst@xxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Userspace PIO access under xen
From: "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>
Date: Mon, 25 Jul 2005 13:22:52 +0100
Cc: Dror Goldenberg <gdror@xxxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
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Thread-topic: [Xen-devel] Userspace PIO access under xen

> 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.

You have to use io_remap_pfn_range for mapping IO space. Using
remap_pfn_range is technically a bug in the i386 code.

I believe the pfn_range functions are preferred over page_range
functions anyhow.


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