panic in 8-CURRENT
Hiroki Sato
hrs at FreeBSD.org
Sun Oct 21 00:45:44 PDT 2007
Hiroki Sato <hrs at freebsd.org> wrote
in <20071019.021408.138664034.hrs at allbsd.org>:
hr> Hiroki Sato <hrs at FreeBSD.org> wrote
hr> in <20071015.034121.120532311.hrs at allbsd.org>:
hr>
hr> hr> I got the following panic with the Oct 14 8-CURRENT kernel. A 2-way
hr> hr> (Opteron) box running GENERIC FreeBSD/i386 kernel with serial console
hr> hr> access, and typing some keys just after "Trying to mount..." line
hr> hr> appears seems to prevent this panic. Without typing any keys the box
hr> hr> remain stopped after displaying the line, and then typing a key will
hr> hr> cause this panic. Whether the panic occurs depends on the time
hr> hr> between displaying the line and typing a key.
hr> hr>
hr> hr> ----(from here)
hr> hr> WARNING: WITNESS option enabled, expect reduced performance.
hr> hr> Trying to mount root from ufs:/dev/ad4s1a
hr> hr> spin lock 0xc0c17a6c (sio) held by 0xc3f0d630 (tid 100004) too long
hr> hr> panic: spin lock held too long
hr> hr> cpuid = 0
hr> hr> KDB: enter: panic
hr> hr> [thread pid 46 tid 100056 ]
hr> hr> Stopped at kdb_enter+0x32: leave
(snip)
hr> I found that this panic occurred only when "options [KDG]DB" were
hr> defined and reproducible on serial-console-enabled HP boxes such as
hr> DL140G3 and ML115. With the options, the same panic occurs even on
hr> 6.2R.
After some investigation, I found it occurs only when options
BREAK_TO_DEBUGGER (or ALT_BREAK_TO_DEBUGGER) is defined. More
specifically, the box stops if the following line exists in sio.c:
|#if defined(KDB) && (defined(BREAK_TO_DEBUGGER) || \
| defined(ALT_BREAK_TO_DEBUGGER))
| /*
| * Enable interrupts for early break-to-debugger support
| * on the console.
| */
| if (ret == 0 && unit == comconsole)
| outb(siocniobase + com_ier, IER_ERXRDY | IER_ERLS |
| IER_EMSC);
|#endif
If this line is removed, no hiccup just after "Trying to mount
root..." and no panic occur. I guess enabling sio's interrupt at
this early stage causes a deadlock, but I am not sure the details of
what happends there.
Anyone who can reproduce this problem?
--
| Hiroki SATO
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 187 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-current/attachments/20071021/662ca6ac/attachment.pgp
More information about the freebsd-current
mailing list