Re: [Xen-devel] Kernel Oops when reading kernel_page_tables debugfs file

[Vivien Bernet-Rollande <vbernetr@xxxxxxxxx>]

On Mon, Nov 29, 2010 at 4:20 PM, Konrad Rzeszutek Wilk
<konrad.wilk@xxxxxxxxxx> wrote:
> On Wed, Nov 24, 2010 at 05:07:49PM +0100, Vivien Bernet-Rollande wrote:
>> Hi list.
>> I'm  currently trying to get a device driver to work on Xen dom0. The driver
>> maps PCI space to userland, and for some reason I have yet to figure, it
>> doesn't work.
>
> Did you set VM_IO on your mapping?
>

The driver doesn't set the VM_IO flag itself. However, it calls
io_remap_pfn_range(), which is a macro wrapper around
remap_pfn_range(). The later does :
vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;

So the VM_IO flag is set. I actually corrected the bug by adding the
_PAGE_IOMAP flag in the vma->vm_pgprot.

Shouldn't remap_pfn_range() set that flag if VM_IO is set ?

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