Looking for help on strange Kernel Trap 12

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Hello everyone,

I am looking for help on producing a core-dump or some other solution to
survive a strange kernel panic, which begins to appear from the =
beginning of
August, and persists in recent kernels, including the kernel made from
yesterday's source. It seemed that the panic was triggered by a heavy =
swap
load, and I were failed to make a coredump or drop into ddb(1) because =
it
finally stops to respond when sync'ing buffers with another panic, =
instead
of rebooting or dumping.

When I have cvsup'ed to the recent -CURRENT code and installed a new =
kernel,
it seemed to be frangible when having a heavy swap load, which results =
in a
kernel trap 12, which seemed to be occuring on ATA or NIC software
interrupt. What's worse, the panic always triggers a more panic, the
dual-panic will finally cause the system stop to respond, instead of =
dump
the core and restart, this generates a bit trouble for me because I can =
not
get access to the direct console often when I am not at the hosting =
room.

I think the stability, especially stability under heavy load is =
important
for FreeBSD, so I would like to provide some help to solve, or at least,
locate the problem. I have tried to make a core dump, however I failed
because the two panic simply eliminated the possiblity of giving me a =
chance
to fall into ddb(1).

Currently I can provide the following information, and of course if =
that's
not enough, just fell free to write me.

Software installed on the computer are: FreeBSD 5.1-CURRENT, pure-ftpd,
apache2 installed from port with default options.

Hardware: Pentium II-266, 64MB RAM, Intel Pro-100 NIC, ACPI enabled.

The kernel configuration is tweaked, among other things, I have enabled
AUTO_EOI_1, DEVICE_POLLING, and CC option -fno-builtin. Also, I have =
enabled
-O6 with WANT_FORCEDOWNGRADE=3D1 in /etc/make.conf, however, when I have
rebuilt the system with only -O1 the problem persists.

Any ideas?

Thanks in advance!

Cheers,
Xin LI
Frontfree Technology Network