I am using NetBSD/i386 V2.0.2 and frequently on my servers if I try:
cd /kern
tail msgbuf
I receive a: "Segmentation fault"
Not 100% of the time, but more than not.
Has this been observed before ? I can't find mention of it.
Thanks
Scott
Scott R. Burns
NETCN Technologies Inc.
Suite 135 - 4474 Blakie Road
London, , Canada
N6L 1G7
Voice: +1.519.652.0401
Fax: +1.519.652.9275

2005.08.21 18:02:44 +0000, Scott R. Burns wrote:
| I am using NetBSD/i386 V2.0.2 and frequently on my servers if I try:
|
| cd /kern
| tail msgbuf
|
| I receive a: "Segmentation fault"
|
| Not 100% of the time, but more than not.
|
| Has this been observed before ? I can't find mention of it.

FWIW, I can't reproduce this on 2.0_STABLE or 3.99.8.
-- Rui Paulo

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3.99.7:

root@loan8cd /kern
root@loan8tail msgbuf
tail: msgbuf: File too large

at least no crash less and cat display it fine.

2005/8/22, Hubert Feyrer <hubertf (AT) gmx (DOT) de>:
In article <@Netcontech.Comyou wrote:
I am using NetBSD/i386 V2.0.2 and frequently on my servers if I try:

cd /kern
tail msgbuf

I receive a: "Segmentation fault"

Not 100% of the time, but more than not.

Has this been observed before ? I can't find mention of it.

Poking it seems that the mmap() in forward.c:305 returns a 0 pointer (see
below0, which seems pretty strange to me. I can understand why mmap()
would not work on this kind of file, but I'd argue that tail(1) should
fall back to just open(2) and maybe lseek(2) and read(2) then.

Looking at other implementations (source) may be interesting

- Hubert

(gdb) run /kern/msgbuf
The program being debugged has been started already.
Start it from the beginning? (y or n) y

Starting program: / /kern/msgbuf

Breakpoint 1, rlines (fp=0x4810a340, off=10, sbp=0xbfbff3a0)
at /
304 while (off) {
(gdb) p off
$9 = 10
(gdb) p mmap_size
$10 = 16368
(gdb) p mmap_offset
$11 = 0
(gdb) step
305 start = mmap(NULL, (size_t)mmap_size, PRT_READ,
(gdb)
307 if (start == MAP_FAILED) {
(gdb) p start
$12 = 0x0
(gdb) print *start
Error accessing memory address 0x0: Invalid argument.
(gdb)

Sun, Aug 21, 2005 at 11:54:38PM +0100, Rui Paulo wrote:
FWIW, I can't reproduce this on 2.0_STABLE or 3.99.8.

RCS file: /,v

revision 1.24
date: 2005/05/20 13:16:54; author: chs; state: Exp; lines: +1 -2
kernfs does not support mmap(), remove code that pretends that it does.

Martin