lkml.org 
[lkml]   [2011]   [Apr]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/4] x86,xen: introduce x86_init.mapping.pagetable_reserve
On Mon, 18 Apr 2011, H. Peter Anvin wrote:
> On 04/18/2011 07:09 AM, Stefano Stabellini wrote:
> >
> > Sorry, I don't mean to be pushy, it is just that I'll be AFK for 12 days
> > starting from next Friday and I think that this issue should really be
> > fixed in time for the 2.6.39 release, otherwise no 2.6.39 kernels will
> > be able to boot on any xen system.
>
> YOU STILL HAVEN'T PROPOSED ANY SEMANTICS.
>
> The semantics of a hook is a description of what the preconditions are,
> what the postconditions are, and what exactly they are allowed or not
> allowed to do.
>
> This is a real pain to do, *exactly because hooks are a real pain*.
> Most hooks that have been put in has been "oh, just do something at
> point X in the code", which is a case of definition by implementation,
> which is exactly how we ended up with the current mess.
>


x86_init.mapping.pagetable_setup_start(start, max_end)

Notifies the subarch that the kernel early startup intends to
use pages as page table pages.
These pages will have physical addresses in the range
start..max_end.

Can be called multiple times to setup kernel page table pages,
always in a pair with x86_init.mapping.pagetable_setup_done.
It must be called before x86_init.paging.pagetable_setup_start().

Preconditions: no kernel code after the 32-bit kernel entry point
has hooked any new page table pages into the active page table
except between a pair of
x86_init.mapping.pagetable_setup_start and
x86_init.mapping.pagetable_setup_done.

Postcondition: pages in the range start..max_end may be used as
page table pages and hooked into active page tables.
Pages in this range may NOT be used for any other purpose.


x86_init.mapping.pagetable_setup_done(real_end)

Notifies the subarch that the initial memory mapping is complete,
and of the actual range of pages used.

Preconditions:

x86_init.mapping.pagetable_setup_start was previously called; the
arguments to the calls must satisfy start <= real_end <= max_end

The pages in the range start..real_end have been hooked into the
active page table.
The pages in the range real_end..max_end are not currently in use.

Postconditions:

Pages in the range real_end..max_end may be used as normal
memory.

Pages in the range start..real_end might be hooked into the active
page table and cannot be used for other purposes.

New page table pages must be allocated using
pv_mmu_ops.alloc_pte/pmd/pud.


\
 
 \ /
  Last update: 2011-04-18 19:23    [W:0.164 / U:0.400 seconds]
©2003-2014 Jasper Spaans. Advertise on this site