kern/98460 : [kernel] [patch] fpu_clean_state() cannot be disabled for not AMD processors, those are not vulnerable to FreeBSD-SA-06:14.fpu

[Rostislav Krasny]

The following reply was made to PR kern/98460; it has been noted by GNATS.

From: Rostislav Krasny <rosti.bsd at gmail.com>
To: Bruce Evans <bde at zeta.org.au>
Cc: freebsd-gnats-submit at freebsd.org
Subject: Re: kern/98460 : [kernel] [patch] fpu_clean_state() cannot be
 disabled for not AMD processors, those are not vulnerable to
 FreeBSD-SA-06:14.fpu
Date: Fri, 9 Jun 2006 23:05:06 +0300

 On Wed, 7 Jun 2006 12:09:10 +1000 (EST)
 Bruce Evans <bde at zeta.org.au> wrote:
 
 > > And then you want to call the fpu_clean_state() function conditionally,
 > > like in following example?
 > >
 > > if (cpu_fxsr & CPU_FXSR_NEEDCLEAN)
 > >        fpu_clean_state();
 > 
 > Not quite like that.  In my version there is no function call -- the code
 > is excecuted in the one place where it is needed, so there is no function
 > call overhead or possible branch prediction oferhead for the function call.
 
 Could you please explain in more detail how that can be done?