[PANIC] More details about problem with syscons(4)
Wojciech A. Koszek
dunstan at freebsd.czest.pl
Mon Jan 9 08:59:07 PST 2006
Hello,
There is a problem I've reported earlier:
http://lists.freebsd.org/pipermail/freebsd-current/2005-November/058221.html
Analisis has shown that allscreen_flags="80x50" or
allscreen_flags="MODE_278" is a reason. After I removed it and run my
box with typical 80x25 console, everything seems to be fine.
I'm getting that problem from time to time, which is really unpleasant
(especially because it happens after fsck'ing your filesystem when it's
mounted read/write). For some time I've been running modified
schistory.c from src/sys/dev/syscons. It's here:
http://freebsd.czest.pl/dunstan/FreeBSD/vidcontrol/schistory.c
Successful booting with my printf's looks like that:
http://freebsd.czest.pl/dunstan/FreeBSD/vidcontrol/dmesg_success.txt
I got a panic, obtained a crash dump and was able to track it. Result is
here:
http://freebsd.czest.pl/dunstan/FreeBSD/vidcontrol/syscons_crash.txt
As you see from attached information, I'm running with:
options SC_PIXEL_MODE
options SC_HISTORY_SIZE=20000
Complete kernel configuration is here:
http://freebsd.czest.pl/dunstan/FreeBSD/vidcontrol/LAPTOP
http://freebsd.czest.pl/dunstan/FreeBSD/vidcontrol/devel
http://freebsd.czest.pl/dunstan/FreeBSD/vidcontrol/debug
http://freebsd.czest.pl/dunstan/FreeBSD/vidcontrol/security
rwatson@ suggested that this highly XXXed part in schistory might be a
problem, since this area is where memory allocation happens. I belive my
analisis can confirm it:
(kgdb) list *0xc05db628
0xc05db628 is in sc_alloc_history_buffer
(/usr/src/sys/dev/syscons/schistory.c:154).
149
150 /* FIXME: XXX no good? */
151
152 sc_vtb_clear(history, scp->sc->scr_map[0x20],
153 SC_NORM_ATTR << 8);
154 SC_DBG("prev_history=%p", prev_history);
155 if (prev_history != NULL)
156 copy_history(prev_history, history);
157 scp->history_pos = sc_vtb_tail(history);
158 SC_DBG("scp->history_pos=%d", scp->history_pos);
--
* Wojciech A. Koszek && dunstan at FreeBSD.czest.pl
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