lkml.org 
[lkml]   [2016]   [Aug]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 5/8] x86/head: remove useless zeroed word
On Mon, Aug 22, 2016 at 6:23 PM, H. Peter Anvin <hpa@zytor.com> wrote:
> On August 22, 2016 2:48:46 PM PDT, Andi Kleen <andi@firstfloor.org> wrote:
>>Josh Poimboeuf <jpoimboe@redhat.com> writes:
>>
>>> This zeroed word has no apparent purpose, so remove it.
>>>
>>> Brian Gerst says:
>>>
>>> "FYI the word used to be the SS segment selector for the LSS
>>> instruction, which isn't needed in 64-bit mode."
>>>
>>
>>Seems dangerous. It wouldn't surprise me if some CPUs or x86 emulations
>>load it anyways and trigger page faults if there is really nothing
>>there.
>>
>>-Andi
>
> Yes, seems pointlessly risky.

It was added in commit 9cf4f298e29abba25c16679fe7be70898223167e,
copied from 32-bit but never used. It doesn't look like we ever used
LSS on 64-bit.

--
Brian Gerst

\
 
 \ /
  Last update: 2016-09-17 09:57    [W:0.041 / U:0.052 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site