From: root@candle.uucp (Bruce Momjian)
Subject: Turning on cache causes random kernel panics, core dumps
Organization: a consultant's basement
Date: Wed, 9 Sep 1992 02:38:18 GMT
X-Newsreader: Tin 1.1 PL5

I am running SCO Unix SVr3.2 2.0 on an Everex Next 386/33.  The box is
stuffed to the gills, with 2 SCSI hard drives, 2 SCSI tape drives, an
Arcnet multiport card, an ethernet card running TCP/IP, and two floppy
drives.

With the motherboard cache is turned off, it runs fine.  When the cache
is turned on, the system dumps core of executables at random, and
finally kernel panics.  Attached are tracebacks of three of those
panics.  I notice that the panics seem to all occur in ttxput().  I
tried removing the Arcnet and ethernet cards, but the problem did not go
away.  

The first panic occured when the system successfully went into
multi-user mode, and I was in an application.  The second was
caused by my typing 'ps -ef' at the console.  The third was caused by the
TCP/IP starting up before generating logins.  In all cases, I was the
only one using the system, and all occurred within 10 minutes of boot. 
I still have the panic images.

The core dumps seem to occur most often in the tty database startup
section before logins are started, and can also report 'no space', even
though there is tons of space on all drives.  Core dumps can also happen
in applications.

Many thanks to those who responded to my 'modem hanging system' query. 
I will be able to prevent the hangs now.  Thanks for reading and perhaps
responding to this lengthy posting.

--------------------------------------------------------------------------
			PANIC WHEN STARTING APPLICATION

$ crash brs_dump
dumpfile = brs_dump, namelist = /unix, outfile = stdout
> t
STACK TRACE FOR PROCESS 19:
STKADDR   FRAMEPTR  FUNCTION  POSSIBLE ARGUMENTS
e0000c24  e0000c3c  prf_task (e,d008c629,d00b0790,160)
e0000c44  e0000c68  cmn_err  (3,d00b1058,e,d00a2e7c)
e0000c70  e0000c94  k_trap   (e0000ca0)
Trap e    e0000ca0  cmntrap  from d009b6d0 in ttxput  
  ax:      1b cx:      40 dx: 1893b7b bx:    1805 fl:    10246 ds: 160 fs:   0
  sp:e0000cd0 bp:e0000d14 si:d00a2e7c di:      1b err:d0100000 es: 160 gs:   0
e0000ca8  e0000d14  ttxput   (d00a2e7c,d10dddd0,3f,d00a2e7c)
e0000d1c  e0000d44  ttwrite  (d00a2e7c,d0100000,4b)
e0000d4c  e0000d58  vidwrite (d00cc708,d010f074,d00c8348,0)
e0000d60  e0000d74  cnwrite  (0,2,d00c8348,d010f074)
e0000d7c  e0000db4  s5writei (d010f074,e0000e38,d00b0b30,52)
e0000dbc  e0000dec  rdwr     (2)
e0000df4  e0000df8  write    (188f92c,1893b3c,52,d0117868)
e0000e00  e0000e2c  systrap  (e0000e38)
          e0000e38  sys_call from 00079274
  ax:       4 cx:       0 dx: 189abe8 bx:      52 fl:      202 ds:  1f fs:   0
  sp:e0000e68 bp:7ffffce8 si: 188f92c di: 1893b3c err:       4 es:  1f gs:   0
> quit

----------------------------------------------------------------------

	PANIC WHEN DOING ps -ef

/u/kernel_dump> crash ps-ef_dump
dumpfile = ps-ef_dump, namelist = /unix, outfile = stdout
> t
STACK TRACE FOR PROCESS 5:
STKADDR   FRAMEPTR  FUNCTION  POSSIBLE ARGUMENTS
e0000c14  e0000c2c  prf_task (6,d008c629,d00b0790,160)
e0000c34  e0000c58  cmn_err  (3,d00b1058,6,d00a2e7c)
e0000c60  e0000c84  k_trap   (e0000c90)
Trap 6    e0000c90  cmntrap  from d009b6da in ttxput  
  ax:      65 cx:      37 dx:  40eebe bx:    1805 fl:    10213 ds: 160 fs:   0
  sp:e0000cc0 bp:e0000d04 si:d00a2e7c di:      65 err:       0 es: 160 gs:   0
e0000c98  e0000d04  ttxput   (d00a2e7c,d10de0a0,36,d00a2e7c)
e0000d0c  e0000d34  ttwrite  (d00a2e7c,0,8228)
e0000d3c  e0000d48  vidwrite (d00cc708,0,d00c8030,96b0)
e0000d50  e0000d64  cnwrite  (0,d011325c)
e0000d6c  e0000d74  sywrite  (301,2,d00c8030,d011325c)
e0000d7c  e0000db4  s5writei (d011325c,e0000e38,d00b0b30,37)
e0000dbc  e0000dec  rdwr     (2)
e0000df4  e0000df8  write    (40d3d0,40ee88,37,d0117868)
e0000e00  e0000e2c  systrap  (e0000e38)
          e0000e38  sys_call from a00037a4
  ax:       4 cx:       0 dx:       2 bx:      37 fl:      202 ds:  1f fs:   0
  sp:e0000e68 bp:7ffffaa4 si:  40d3d0 di:  40ee88 err:       4 es:  1f gs:   0
> quit

--------------------------------------------------------------------

		PANIC WHEN TCP/IP STARTING UP

dumpfile = tcp_dump, namelist = /unix, outfile = stdout
t
> STACK TRACE FOR PROCESS 10:
STKADDR   FRAMEPTR  FUNCTION  POSSIBLE ARGUMENTS
e0000c14  e0000c2c  prf_task (6,d008c629,d00b0790,160)
e0000c34  e0000c58  cmn_err  (3,d00b1058,6,d00a2e7c)
e0000c60  e0000c84  k_trap   (e0000c90)
Trap 6    e0000c90  cmntrap  from d009b6da in ttxput  
  ax:      66 cx:       0 dx:       0 bx:    1805 fl:    10213 ds: 160 fs:   0
  sp:e0000cc0 bp:e0000d04 si:d00a2e7c di:      66 err:       0 es: 160 gs:   0
e0000c98  e0000d04  ttxput   (d00a2e7c,66,0,d00a2e7c)
e0000d0c  e0000d34  ttwrite  (d00a2e7c,0,dbc)
e0000d3c  e0000d48  vidwrite (d00cc708,0,d00c8084,ec00)
e0000d50  e0000d64  cnwrite  (0,d011325c)
e0000d6c  e0000d74  sywrite  (301,2,d00c8084,d011325c)
e0000d7c  e0000db4  s5writei (d011325c,e0000e38,d00b0b30,8)
e0000dbc  e0000dec  rdwr     (2)
e0000df4  e0000df8  write    (4006e0,4013a0,8,4005a8)
e0000e00  e0000e2c  systrap  (e0000e38)
          e0000e38  sys_call from a00037a4
  ax:       4 cx:       0 dx:       0 bx:       8 fl:      202 ds:  1f fs:   0
  sp:e0000e68 bp:7ffffa7c si:  4006e0 di:  4013a0 err:       4 es:  1f gs:   0
> quit

-- 
Bruce Momjian                      |  830 Blythe Avenue
root%candle.uucp@bts.com           |  Drexel Hill, Pennsylvania 19026 
                                   |  (215) 353-9879(w)  853-3000(h)