lkml.org 
[lkml]   [2010]   [Jun]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] x86: OLPC: add support for calling into OpenFirmware (v5)
On 06/18/2010 12:56 PM, Ingo Molnar wrote:
>
> * H. Peter Anvin <hpa@zytor.com> wrote:
>
>> On 06/18/2010 12:42 PM, Andres Salomon wrote:
>>> +
>>> + /* install OFW's PDE permanently into the kernel's pgtable */
>>> + set_pgd(&swapper_pg_dir[OLPC_OFW_PDE_NR], *ofw_pde);
>>> + flush_tlb();
>>> + early_iounmap(base, sizeof(olpc_ofw_pgd) * PTRS_PER_PGD);
>>
>> I just realized... this flush_tlb() is actually not necessary since on x86
>> it is always legal to go from a less permissive configuration to a more
>> permissive, and the initial configuration is "not present" which is
>> maximally nonpermissive.
>>
>> Could you take it out and make sure it still works?
>
> small nit: an optimization barrier would still be needed if the result is
> being relied on by the kernel.
>

In this case the optimization barrier is implicit at the return from an
out of line function.

-hpa


\
 
 \ /
  Last update: 2010-06-18 22:03    [W:0.048 / U:4.928 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site