Date: Fri, 6 Dec 2002 16:41:16 -0800 (PST) From: Julian Elischer <julian@elischer.org> To: FreeBSD current users <current@FreeBSD.ORG> Subject: x86 FPU discard question.. Message-ID: <Pine.BSF.4.21.0212061630120.26728-100000@InterJet.elischer.org>
next in thread | raw e-mail | index | archive | help
As part of shuting down a thread and discarding it, we want to
throw away any floating point context there may be.
Currently this saves out the floating point state to make the fpu
be declared 'unused'. However we dont't need any fpu state saved.
Is there any way to just mark it as 'unused' without bothering to waste
time saving the current FP context? would just doing
PCPU_SET(fputhread, NULL);
be enough?
Currently there is an npxexit() in cpu_thread_exit().
where npxexit() does:
savecrit = intr_disable();
if (curthread == PCPU_GET(fpcurthread))
npxsave(&PCPU_GET(curpcb)->pcb_save);
intr_restore(savecrit);
My guess is that there needs to be some bit set to tell the hardware
that it is unused so that a trap can be generated on the first use by
another thread.
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.4.21.0212061630120.26728-100000>