svn commit: r328625 - in head/sys: amd64/amd64 amd64/ia32 amd64/include dev/cpuctl i386/i386 x86/include x86/x86

Ed Maste emaste at freebsd.org
Wed Jan 31 17:08:16 UTC 2018


On 31 January 2018 at 09:56, Bjoern A. Zeeb
<bzeeb-lists at lists.zabbadoz.net> wrote:
> On 31 Jan 2018, at 14:36, Konstantin Belousov wrote:
>
>> Author: kib
>> Date: Wed Jan 31 14:36:27 2018
>> New Revision: 328625
>> URL: https://svnweb.freebsd.org/changeset/base/328625
>>
>> Log:
>>   IBRS support, AKA Spectre hardware mitigation.
>
>
>>   For existing processors, you need a microcode update which adds IBRS
>>   CPU features, and to manually enable it by setting the tunable/sysctl
>>   hw.ibrs_disable to 0.  Current status can be checked in sysctl
>>   hw.ibrs_active.  The mitigation might be inactive if the CPU feature
>
>
> Can you change the tunable/sysctl to hw.ibrs_enable[d] (and toggle the
> default setting along).

I had a similar thought while the change was in review, but saw that a
number of tunables in similar areas also have negative sense. That
said perhaps (some minor) consistency is not enough of an argument for
the somewhat more confusing sense.


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