WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] Re: [XenPPC] Xencomm for xen/ia64

On Mon, 2006-08-21 at 08:46 +0200, Tristan Gingold wrote:
> Le Vendredi 18 Août 2006 18:39, Hollis Blanchard a écrit :
> > On Fri, 2006-08-18 at 11:04 +0200, Tristan Gingold wrote:
> > > Le Jeudi 17 Août 2006 20:35, Hollis Blanchard a écrit :
> >
> > I'm not sure how it simplifies hcall.c. You always need to create
> > xencomm descriptors, unless you're manually guaranteeing that the
> > dom0_op structures do not cross page boundaries (in which case they are
> > not "linear in memory"). Is that what you're doing?
> For hypercalls issued through privcmd, xencomm descriptors are always created.
> For hypercalls directly issued by kernel inline xencomm is prefered.

How do you guarantee that kernel-created data structures are not
crossing page boundaries? The patch you sent does not do this. Without
that, xencomm_inline() simply cannot work except by luck.

> > > > We need to do one more thing though: we *also* need to change fix up
> > > > the size of longs and pointers in our code (since 32-bit userland is
> > > > passing structures to a 64-bit kernel). So perhaps these two fixup
> > > > passes could be split: we could share the xencomm conversion in common
> > > > code, and PPC arch code could contain the size munging.
> > >
> > > Are structure sizes different on 32 and 64 bits ?
> >
> > Yes, in particular longs and pointers.
> But are longs and pointers used directly in Xen hypercalls ?  I though only 
> sized types (uintNN_t & others) are used.

I have put a lot of work into converting types to be explicitly sized,
but there are still missing pieces. I think Jimi got tired of it, and
started doing the Linux "compat32" conversion. For example, see
drivers/xen/privcmd/compat_privcmd.c .

-- 
Hollis Blanchard
IBM Linux Technology Center


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

<Prev in Thread] Current Thread [Next in Thread>