Re: [PATCH 10/28] i386: map enough initial memory to create lowmem mappings

Jeremy Fitzhardinge
2007-04-23T19:10:45Z

Eric W. Biederman wrote:
> If (cpu_has_pse) it may only be an additional two pages.
> INIT_MAP_BEYOND is currently mapping a lot more then that.
>

Ah, yes. It allocates an extra two pages for pagetables, and then maps
an extra 8MB or so.

>> Would that be necessary? Is there any need to remap it? Couldn't you
>> just do the straightforward phys->virt mapping and use the page where it
>> lies?
>>
>
> Catch-22. If the page is not mapped yet you can't use it where it lies.

Why not? Er, except in the case where the page is needed to map itself
- but that can be dealt with with a transient fixmap mapping.

J