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xen-devel
Re: [Xen-devel] "Iomem mapping not permitted" during windows crash dump
It's not really an i/o page. All 1s means INVALID_MFN, which means the p2m
lookup failed. I suppose Windows may think it is a valid pfn (e.g., an
emulated device?) but that kind of mem can't be granted and never could be.
-- Keir
On 30/01/2010 05:26, "James Harper" <james.harper@xxxxxxxxxxxxxxxx> wrote:
> I've recently noticed that my windows crash dumps fail at around 40-50%
> under GPLPV. 'xm dmesg' shows the following:
>
> (XEN) grant_table.c:350:d0 Iomem mapping not permitted ffffffffffffffff
> (domain 865)
>
> At first I thought that the cause was just a bug in my grant ref code
> but it just occurred to me that this could be happening when Windows
> tries to write out the physical page I have mapped for some other xen
> function. grant_table.c:350 is around here:
>
> if ( !iomem_access_permitted(rd, frame, frame) )
> {
> gdprintk(XENLOG_WARNING,
> "Iomem mapping not permitted %lx (domain %d)\n",
> frame, rd->domain_id);
> rc = GNTST_general_error;
> goto undo_out;
> }
>
> So is that likely to be the cause? I haven't yet checked the pfn that is
> failing against the pages I've mapped for various things but the number
> seems plausible. It used to work... is that check new under 3.4.1-ish?
>
> And whats the solution? At this stage the only think I can think of is
> that it might be reasonable to ignore a small amount of failed writes
> during a crash dump... I haven't yet researched if there is a way to
> tell windows not to write out a given page of memory when doing a crash
> dump.
>
> Thanks
>
> James
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
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