Re: [patch 06/26] Xen-paravirt_ops: paravirt_ops: allocate a fixmap slot

Ingo Molnar
2007-02-28T08:37:56Z

* Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> > Yes. vmalloc would have the annoying side-effect of actually
> > allocating some pages which would be shadowed by the remapping, but
> > I guess get_vm_area would do the job. I'll give it a go.
>
> Hm, this is a bit awkward. We need to map the shared info page fairly
> early - say, around paging_init - but we're still on the bootmem
> allocator at that point, so get_vm_area isn't usable yet. Using a
> fixmap keeps things simple. It seems to me that having a single
> fixmap available is useful for this kind of simple/early mapping, and
> if someone needs to map something larger, then they can put it off
> until get_vm_area() is available...

fair enough. Please rename it to FIX_PARAVIRT_BOOTUP - you can still
rely on it being available later on too, but we'd like to give everyone
the right fundamental idea about this: it's meant to be a limited,
inflexible interface for bootstrap only.

Ingo