Date: Mon, 7 Jun 2004 10:43:21 +0100 From: David Malone <dwmalone@maths.tcd.ie> To: src-committers@FreeBSD.ORG, cvs-src@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/amd64/amd64 fpu.c Message-ID: <20040607094321.GA32159@walton.maths.tcd.ie> In-Reply-To: <20040606091758.GA6354@VARK.homeunix.com> References: <200406060916.i569G2m2097113@repoman.freebsd.org> <20040606091758.GA6354@VARK.homeunix.com>
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On Sun, Jun 06, 2004 at 02:17:58AM -0700, David Schultz wrote:
> It would be great if someone could pick this up and devise the
> appropriate fix. I want to see this bug fixed, but I don't have the
> hardware to do amd64 kernel hacking. I'm happy to help anyone who is
> interested.
I think I've figured out the problem. On SMP systems, fpuinit() is
called before enable_sse() for secondary processors. The ldmxcsr
instruction counts as a sse instruction, so you get an illegal
instruction fault. The patch below switches the order of fpuinit()
and enable_sse() and fixes the problem on my system anyway.
David.
Index: mp_machdep.c
===================================================================
RCS file: /cvs/FreeBSD-CVS/src/sys/amd64/amd64/mp_machdep.c,v
retrieving revision 1.237
diff -u -r1.237 mp_machdep.c
--- mp_machdep.c 16 May 2004 22:11:50 -0000 1.237
+++ mp_machdep.c 7 Jun 2004 09:36:08 -0000
@@ -429,12 +429,12 @@
/* set up CPU registers and state */
cpu_setregs();
- /* set up FPU state on the AP */
- fpuinit();
-
/* set up SSE registers */
enable_sse();
+ /* set up FPU state on the AP */
+ fpuinit();
+
/* A quick check from sanity claus */
if (PCPU_GET(apic_id) != lapic_id()) {
printf("SMP: cpuid = %d\n", PCPU_GET(cpuid));
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