Re: [PATCH] x86: Construct 32 bit boot time page tables in native format.

H. Peter Anvin
2008-01-24T23:12:43Z

Jeremy Fitzhardinge wrote:
> H. Peter Anvin wrote:
>> Yeah, and it's ugly for the kernel proper, so that bit is a
>> no-brainer. It's just a matter of hammering out the details.
>>
>> It doesn't sound from the above that you have any opinion either way
>> about reusing the initial page tables or creating a new set, as long
>> as they're in the same format.
>
> Right.
>
> Xen provides a initial set of pagetables in the appropriate format, so
> what head.S generates is moot. For simplicity I graft the Xen-provided
> pagetables into swapper_pg_dir in xen_start_kernel, so it is the
> functional equivalent to the head.S pagetable construction.
>
> We also don't (yet) support PSE, so that's a non-issue for us too.
>

While we're mucking around in this area, there is another thing which we
should eventually get around to fixing:

we need a set of page tables with an identity mapping as well as the
kernel mapping, for trampolining (during startup, but also during things
like ACPI suspend/resume.) Right now, we let those be the swapper page
tables, but that's probably not really a good idea, since it can hide bugs.

-hpa