Re: [Xen-devel] Re: [Xen-changelog] This adds a patch for the vanilla kernel, to be pushed upstream some

[Gerd Knorr <kraxel@xxxxxxx>]

Rik van Riel <riel@xxxxxxxxxx> writes:

> On Mon, 11 Jul 2005, Xen patchbot -unstable wrote:
> 
> > --- a/linux-2.6-xen-sparse/arch/xen/i386/mm/pgtable.c       Mon Jul 11 
> > 15:43:12 2005
> > +++ b/linux-2.6-xen-sparse/arch/xen/i386/mm/pgtable.c       Mon Jul 11 
> > 15:46:46 2005
> 
> >     if (PTRS_PER_PMD == 1 || !pgd)
> >             return pgd;
> >  
> > +   if (!HAVE_SHARED_KERNEL_PMD) {
> > +           /* alloc and copy kernel pmd */
> > +           unsigned long flags;
> > +           pgd_t *copy_pgd = pgd_offset_k(PAGE_OFFSET);
> > +           pud_t *copy_pud = pud_offset(copy_pgd, PAGE_OFFSET);
> 
> I don't understand how the code inside this if condition
> ever gets to run.  Surely the previous test should catch
> the non-PAE case already ?

It's about PAE mode.  xenlinux in PAE mode does _not_ have a shared
PMD for the kernel address space.

  Gerd

-- 
panic("it works"); /* avoid being flooded with debug messages */

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