[PATCH] x86 e820: only void usable memory areas in memmap=exactmap case

[Thomas Renninger]

On Friday, January 11, 2013 08:16:52 AM Yinghai Lu wrote:
> On Fri, Jan 11, 2013 at 4:33 AM, Thomas Renninger <trenn at suse.de> wrote:
...
> > -               e820.nr_map = 0;
> > +               /*
> > +                * Remove all usable memory (this is for kdump), usable
> > +                * memory will be passed via memmap=X at Y parameter
> > +                */
> > +               e820_remove_range_type(E820_RAM);
> 
> We may need to keep exactmap intact.
Why?
Kexec/kdump should have been the only user?
If older/current kexec calls still add ACPI maps via memmap=X#Y,
they should already exist in the original e820 map and fall off or
get glued to one region if (wrongly) overlapping via sanitize_map.
 
> but could add another one like exact_ram_map
> or extend to have memmap=exactmap=ram or etc.

I would avoid that if anyhow possible because then you run into
kexec vs kernel version problems.

Maybe I should explicitly post (out of this thread) the patch to the
kexec list.
If nobody can come up with a strong reason, it should be ok?

   Thomas