cvs commit: src/sys/amd64/amd64 mp_machdep.c src/sys/i386/i386 mp_machdep.c

Nate Lawson nate at
Thu Nov 8 13:29:34 PST 2007

Kris Kennaway wrote:
> Colin Percival wrote:
>> cperciva    2007-11-08 19:45:20 UTC
>>   FreeBSD src repository
>>   Modified files:        (Branch: RELENG_7)
>>     sys/amd64/amd64      mp_machdep.c     sys/i386/i386       
>> mp_machdep.c   Log:
>>   Change the default for hyperthreading (or, generally speaking, cases
>>   where the L1 cache is shared between CPUs) to disabled for security
>>   reasons.  As in earlier releases, this can be changed by setting
>>   machdep.hyperthreading_allowed=1 in /boot/loader.conf.
>>     This is not an MFC -- no seatbelts in CURRENT.
>>     Approved by:    re (kensmith)
>>   Security:       See FreeBSD-SA-05:09.htt for background material.
>>     Revision   Changes    Path
>>  +1 -1      src/sys/amd64/amd64/mp_machdep.c
>>  +1 -1      src/sys/i386/i386/mp_machdep.c
> What are you waiting for to happen in HEAD, and what work are you doing
> to expedite that?

I'm still waiting for what will be done to prevent the attack on
uniprocessor or multi-core machines (shared L2).  Continuing to focus on
hyperthreading is like locking the screen door on your submarine.


More information about the cvs-src mailing list