Re: Corrupt data when reading filesystems under Linux guest

[jdev%panix.com@localhost (Jed Davis)]

In article <20050610225426.GC4785%antioche.eu.org@localhost>,
Manuel Bouyer  <bouyer%antioche.eu.org@localhost> wrote:
> On Fri, Jun 10, 2005 at 06:59:14AM +0000, Jed Davis wrote:
> > In article <1118281429.532953.2723.nullmailer%yamt.dyndns.org@localhost>,
> > YAMAMOTO Takashi  <yamt%mwd.biglobe.ne.jp@localhost> wrote:
> > > 
> > > besides that, xen_shm assumes an arbitrary request can be mapped into
> > > a single contiguous virtual address range.  it's wrong.
> > 
> > Also, it assumes that it will be mapping pages for only one xbd request
> > at a time; see XENSHM_MAX_PAGES_PER_REQUEST.  That will need some
> > adjusting if I want to piece together a whole MAXPHYS... and, while I'm
> > in this file, I wonder: is xen_shm's big piece of VM actually big enough
> > to handle use by both disk and net devices?
> 
> Yes, it should. And there is a callback mechanism to defer a request in
> case of resource shortage at this level.

Ah, good.  I saw all the ENOMEMs, but I hadn't looked at where they were going.

> > won't the size of _xen_shm_vaddr2ma[] be a little harder to manipulate
> > post-linking?
> 
> Sure, I didn't intend to have xen_shm_size patchable.

There's a comment nearby to the effect that the size of the VM area is
in a variable rather than just a constant in order to make it patchable,
which is why I was confused.  It looks like it would work for reducing
the size, at least.


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