From owner-freebsd-hackers Mon May 7 14:39: 3 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from segfault.kiev.ua (segfault.kiev.ua [193.193.193.4]) by hub.freebsd.org (Postfix) with ESMTP id 8AC1437B422 for ; Mon, 7 May 2001 14:38:51 -0700 (PDT) (envelope-from netch@iv.nn.kiev.ua) Received: (from uucp@localhost) by segfault.kiev.ua (8) with UUCP id AOW48951; Tue, 8 May 2001 00:38:37 +0300 (EEST) (envelope-from netch@iv.nn.kiev.ua) Received: (from netch@localhost) by iv.nn.kiev.ua (8.11.3/8.11.3) id f475W6H00549; Mon, 7 May 2001 08:32:06 +0300 (EEST) (envelope-from netch) Date: Mon, 7 May 2001 08:32:06 +0300 From: Valentin Nechayev To: Rohit Rakshe Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: FPU exception, kernel panic Message-ID: <20010507083206.A511@iv.nn.kiev.ua> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ; from rakshe@cs.umn.edu on Sun, May 06, 2001 at 05:14:08PM -0500 X-42: On Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Sun, May 06, 2001 at 17:14:08, rakshe (Rohit Rakshe) wrote about "Re: FPU exception, kernel panic": (I cannot even guarantree 50% this is the same problem, but...) There were some reports in current@ about incorrect usage of i586_bzero() which uses FPU for zero-filling. It generated random kernel panics mainly on K6-2, also on P5-MMX and similars. You can try to disable such bzero, but IMHO it is reasonable to upgrade to 4.3-RELEASE (RELENG_4_3) first. > I guessed I asked too much. Can someone please tell me just this: > > "How do I translate 48 bit address (segment descriptor:offset) to a > linear address which gdb can understand ?" > > > > I modified some TCP and UDP code in FreeBSD 4.1 and suddenly started > > getting (almost repeatable) kernel panics. This is how it looks like > > from remote gdb: > > > > (kgdb) bt > > #0 0xc0192e58 in panic (fmt=0xc035c076 "npxintr from nowhere") at > > ../../kern/kern_shutdown.c:550 > > #1 0xc0303c6c in npx_intr (dummy=0x0) at ../../i386/isa/npx.c:721 > > #2 0xc02e1052 in Xfpu () > > #3 0xc019824d in softclock () at ../../kern/kern_timeout.c:131 > > . > > . > > . > > (kgdb) list > > 126 } else { > > 127 c->c_flags = > > 128 (c->c_flags & > > ~CALLOUT_PENDING); > > 129 } > > 130 splx(s); > > 131 c_func(c_arg); > > 132 s = splhigh(); > > 133 steps = 0; > > 134 c = nextsoftcheck; > > 135 } > > . > > . > > . > > (kgdb) > > #1 0xc0303c6c in npx_intr (dummy=0x0) at ../../i386/isa/npx.c:721 > > 721 panic("npxintr from nowhere"); > > (kgdb) p npxproc > > $5 = 0 > > (kgdb) p npx_exists > > $6 = 1 '\001' > > . > > . > > . > > (kgdb) info all-registers > > eax 0x12 18 > > ecx 0xc03a60a0 -1069916000 > > edx 0x400000 4194304 > > ebx 0xcbc56540 -876255936 > > esp 0xc0361354 0xc0361354 > > ebp 0xc0361410 0xc0361410 > > esi 0x400000 4194304 > > edi 0x400000 4194304 > > eip 0xc019824d 0xc019824d > > eflags 0x346 838 > > cs 0x8 8 > > ss 0x10 16 > > ds 0x400010 4194320 > > es 0x10 16 > > fs 0x0 0 > > gs 0x0 0 > > (kgdb) info float > > status 0xc8f5: exceptions: INVALID DIVZ UNDERF LOS FPSTACK; flags: 1000; > > top 1 > > control 0x6620: compute to 53 bits; round DOWN; mask: LOS; > > warning: reserved bits on: 0x6000 > > > > last instruction: opcode 0x2825; pc 0x71a4:0x2824c316; operand > > 0xf800:0x8176640 > > regno tag msb lsb value > > %st(7) valid 0000000008179a802825 Denormal (0 as a double) > > %st(6) valid 71a42824c31600000000 Unnormal (NaN) > > %st(5) valid 08176640282571a42824 Unnormal (NaN) > > %st(4) valid c8910818f9380818f800 Unnormal (NaN) > > %st(3) valid 282571a42824c316bfbf Unnormal (NaN) > > %st(2) valid e82808176620089c3000 Unnormal (NaN) > > %st(1) valid 00000032000000010001 Denormal (0 as a double) > > %st(0) => valid 0000000000240818f800 Denormal (0 as a double) > > > > > > So, this means that there was a FPU exception in kernel, right ? > > > > 1. The code which I added in kernel does not use any floats. So I am > > wondering why this problem should happen at all. > > > > 2. pc register in FPU should give address of the instruction which caused > > this exception, right ? > > > > 3. If yes, how do I translate this 48 bit address in a linear address > > which gdb can understand ? /netch To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message