[U-Boot-Users] about to CONFIG_LOGBUFFER ..

[U-Boot-Users] about to CONFIG_LOGBUFFER ..

[Yongdae, Shin]

I do not understand the CONFIG_LOGBUFFER.
What's the CONFIG_LOGBUFFER?
How to use the CONFIG_LOGBUFFER in U-Boot and Linux Kernel?

Why that excluded log buffer in linux system memory?

[U-Boot-Users] about to CONFIG_LOGBUFFER ..

[Wolfgang Denk]

In message <4111DB52.40308@newmi.co.kr> you wrote:
> I do not understand the CONFIG_LOGBUFFER.
> What's the CONFIG_LOGBUFFER?

It's a feature so that both U-Boto and Linux can use the same memory as log buffer.

> How to use the CONFIG_LOGBUFFER in U-Boot and Linux Kernel?

In U-Boot, for example the POST code can output messages to  the  log
buffer.  Or  you  can  redirect  the standard output of (some or all)
commands to be stored in the log buffer.

In Linux, the syslog mechanism makes use of the log buffer.

This way you can for example have the standard Linux systlog  toolset
process  the  boot  messages  or  the  POST diagnosis. Or you can use
U-Boot to print the Linux kernels log buffer after a crash.

> Why that excluded log buffer in linux system memory?

This is to make sure that the log buffer is kept intact over reboots.
Even after a Linux crash you can use U-Boot (or Linux after the  next
boot) to print the log buffer contents.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
"Pull the wool over your own eyes!"                - J.R. "Bob" Dobbs

[U-Boot-Users] about to CONFIG_LOGBUFFER ..

[Wolfgang Denk]

In message <4111F858.6080206@newmi.co.kr> you wrote:
>
> Ok! I know that log buffer address in U-boot.
> How to know the log buffer address in Linux Kernel?
> 
> Then, how to assign log buffer address for Linux Kernel.
> The "do_syslog()" in Linux kernel, log_buffer is only static array variable.

You need a modified / extended Linux kernel for this feature.

Please see the linux-2.4 Linux kernel tree on our CVS server;  search
for CONFIG_LOGBUFFER.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
"I used to think that the brain was the most wonderful  organ  in  my
body. Then I realized who was telling me this."        - Emo Phillips