Date: Mon, 7 May 2001 08:32:06 +0300 From: Valentin Nechayev <netch@iv.nn.kiev.ua> To: Rohit Rakshe <rakshe@cs.umn.edu> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: FPU exception, kernel panic Message-ID: <20010507083206.A511@iv.nn.kiev.ua> In-Reply-To: <Pine.GSO.4.31.0105061711210.15916-100000@melchizedek.cs.umn.edu>; from rakshe@cs.umn.edu on Sun, May 06, 2001 at 05:14:08PM -0500 References: <Pine.GSO.4.31.0105051400070.16637-100000@mercury.cs.umn.edu> <Pine.GSO.4.31.0105061711210.15916-100000@melchizedek.cs.umn.edu>
next in thread | previous in thread | raw e-mail | index | archive | help
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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20010507083206.A511>