6 Apr
2011
6 Apr
'11
12:50 a.m.
Checkout
http://svn.reactos.org/svn/reactos/trunk/rosapps/applications/sysutils/util…
for kicks
On Apr 5, 2011 8:11 PM, "Minas Abrahamyan" <minas.subs(a)gmail.com> wrote:
Hi all,
I'm going to implement dmesg.exe, a ROS application to read dmesg/kmsg
buffer (debug messages in kernel buffer),
which is filled in by appropriate patch 6018
(here: http://www.reactos.org/bugzilla/show_bug.cgi?id=6018 ) (BTW,
it's not yet reviewed and not applied!).
So I'm requesting advice on:
What would be the better way for user-mode code to get the contents of
kmsg buffer in kernel-space (kdbg)?
Shortly:
Linux has special system call "syslog" (man 2 syslog)
FreeBSD uses its special sysctl interface to kernel along with
'kern.msgbuf' parameter.
My questions:
Do we need special system call like Linux, or even more, the whole
family of them (sysctl('*')) as in BSD?
How to implement simple system call for it, now?
---
Now detailed info for unices:
Linux case:
* syslog(2) - read and/or clear kernel message ring buffer; set
console_loglevel
int syslog(int type, char *bufp, int len);
* also /proc/kmsg virtual file, which when being read returns buffer
contents
==excerpt from man proc ==
/proc/kmsg
This file can be used instead of the syslog(2) system
call to read kernel messages. A
process must have superuser privileges to read this
file, and only one process should read
this file. This file should not be read if a syslog
process is running which uses the sys‐
log(2) system call facility to log kernel messages.
Information in this file is retrieved with the dmesg(1)
program.
==eo exerpt==
dmesg in FreeBSD:
Parameter 'kern.msgbuf' given to sysctl(3) returns contents of kernel
message buffer.
There is also 'kern.msgbuf_clear' to clean the buffer.
---
WBR,
Minas Abrahamyan
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