Re: Problems with UVM pagefaults

["Cherry G. Mathew" <cherry.g.mathew%gmail.com@localhost>]

Hi Roger,

I've got two immediate thoughts:

On 9 January 2013 00:46, Roger Pau Monné <roger.pau%citrix.com@localhost> wrote:

> This device works by passing a memory region previously allocated with
> mmap(NULL, size, prot, MAP_ANON | MAP_SHARED, -1, 0). This region is

i) wire down the mapping with MAP_WIRED

This will prevent it from being paged in/out and thus pagefaulting on access.

...

> So far I've been able to get the ptes, pass them to Xen and stablish the
> mapping. Writing to that memory area from userspace seems to work fine
> (using pread), but the problem comes when the userspace program executes
> something like:
>
> pwrite(fd, buf,...)

ii) If this is a xen specific page aliasing issue (where a writeable
page is disallowed because it points to RO pagetables mappings of
domains), perhaps that's nothing to do with UVM ?

Cheers,

-- 
~Cherry