Date: Mon, 7 Jan 2002 16:38:16 -0500 (EST) From: Daniel Eischen <eischen@pcnet1.pcnet.com> To: Nate Williams <nate@yogotech.com> Cc: Dan Eischen <eischen@vigrid.com>, arch@FreeBSD.ORG Subject: Re: Request for review: getcontext, setcontext, etc Message-ID: <Pine.SUN.3.91.1020107163310.29377A-100000@pcnet1.pcnet.com> In-Reply-To: <15418.4935.657413.312252@caddis.yogotech.com>
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[CC's trimmed] On Mon, 7 Jan 2002, Nate Williams wrote: > > Search for FP_SAVE_UC and FP_RESTORE_UC. You should find it in > > pthread_private.h (where it is defined) and referenced in > > uthread_kern.c and uthread_sig.c (src/lib/libc_r/uthread/). > > Found it. However, I could find the definition for mc_fpregs. See src/sys/sys/ucontext.h and src/sys/i386/include/ucontext.h. > Also, forgive my ignorance, but why are we using fnsave instead of > fsave? From my reading of the x86 manuals, it would seem that there is > the possibility of getting bogus FPU results with fnsave (vs. fsave) > since by using fsave, we give the FPU a chance to finish up the current > FPU operations before we save the state? I could see where they might > be a race where we might end up storing intermediate results of the FPU > in some instances. > > Or, is there something else I'm missing? (The reason I ask is that the > JDK uses fsave to be 'safe', but maybe it's not buying us anything other > than warm fuzzies. :) I don't know :-) That's what it was using when John Birrell was maintaining libc_r. I can always change it... -- Dan Eischen To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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