Date: Tue, 16 Jul 2002 22:47:13 -0700 From: Bakul Shah <bakul@bitblocks.com> To: Julian Elischer <julian@elischer.org> Cc: Szilveszter Adam <sziszi@bsd.hu>, freebsd-current@FreeBSD.ORG Subject: Re: Interesting panic very early in the boot Message-ID: <200207170547.BAA03460@illustrious.cnchost.com> In-Reply-To: Your message of "Sun, 14 Jul 2002 15:15:44 PDT." <Pine.BSF.4.21.0207141511470.58654-100000@InterJet.elischer.org>
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I've run into a very similar bug -- the kernel panics almost
right after it is started by the loader. With remote gdb
I've traced it to this point so far:
(kgdb) target remote /dev/cuaa0
Remote debugging using /dev/cuaa0
pmap_set_opt () at /usr/src/sys/i386/i386/pmap.c:449
449 if (*pte)
warning: Unable to find dynamic linker breakpoint function.
GDB will be unable to debug shared library initializers
and track explicitly loaded dynamic code.
warning: shared library handler failed to enable breakpoint
(kgdb) where
#0 pmap_set_opt () at /usr/src/sys/i386/i386/pmap.c:449
#1 0xc0307c64 in pmap_bootstrap (firstaddr=3146924, loadaddr=0)
at /usr/src/sys/i386/i386/pmap.c:403
#2 0xc03056b2 in getmemsize (first=4947968)
at /usr/src/sys/i386/i386/machdep.c:1473
#3 0xc0305e2f in init386 (first=4947968)
at /usr/src/sys/i386/i386/machdep.c:1817
(kgdbl
444 /* Turn on PG_G for text, data, bss pages. */
445 va = (vm_offset_t)btext;
446 endva = KERNBASE + KERNend;
447 while (va < endva) {
448 pte = vtopte(va);
449 if (*pte)
450 *pte |= pgeflag;
451 va += PAGE_SIZE;
452 }
453 invltlb(); /* Insurance */
(kgdb) p/x va
$2 = 0xc012be70
I can't get to pte for some reason. So hand computing vtopte(va) we get
(kgdb) p/x btext
$3 = 0xc012be70
(kgdb) p PTmap
$7 = 0xbfc00000
(kgdb) p/x PTmap+0xc012b
$8 = 0xbff004ac
This address matches the page fault address. It is a
supervisor read, protection violation fault.
More details:
This is with today's (July 16) kernel (synced at about 5PM
PDT) on a Ppro system. This system can take two PPros but
I've plugged in just one Pentium Pro. It has 64MB ECC
memory. I'll continue investigating but I haven't been in
this part of code for ages hence the call for help!
If it matters, a kernel built from sources before the KSE
changes works fine on this machine.
Thanks for any hints.
-- bakul
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