serial console

[KokHow Teh]

Hi;
      I have tried with 4 types of command lines with my linux kernel with
devfs and serial device compiled in and none gives me the desired results:

(1)   console=tts/0,115200n8 OR console=ttyCPM0,115200n8

      no serial console output at all during boot time but it gives me
login prompt at the end.

(2)   without "console=" OR console=ttyS0,115200n8

      serial console output fine during bootup but only until the point
when it prints out "Freeing unused kernel memory: 232k init 4k prep". After
that, the serial console output is garbled.

      So this has not solved my problem. I need more advice. Here are some
more questions and observations:

(1)   David Jander's comment:

I don't know exactly what I am talking about right now, but the string
"tts/0"
in the console-line sounds suspicious to me. AFAIK when using devfs still
device names on the kernel-commandline have to be old-style.
Just a guess: try using "console=ttyS0,115200n8" and see if this helps.

      Is it confirmed that kernel-commandline has to be old-style even
though the kernel is using devfs?

(2)   Vitaly Bordug's suggestion of using "console=ttyCPM0". May I know
where is ttyCPM0 defined and how is it bound to the serial console device
driver in the source?

      Thanks for any input and pointer.

Regards,
TEH



Vitaly Bordug <vbordug at ru.mvista.com> on 10/04/2005 11:16:10 PM

To:    KokHow.Teh at marconi.com
cc:    linuxppc-embedded list <linuxppc-embedded at ozlabs.org>

Subject:    Re: serial console



> On Tuesday 04 October 2005 08:54, KokHow Teh wrote:
>
>>Hi;
>>      I have debian linux running on my PQ2FADS-ZU with devfs and serial
>>driver compiled in. I have read Documentation/serial-console.txt and I
have
>>tried both passing "console=" option as well as without passing that to
the
>>kernel and both don't give me the expected results.
>>      When I pass "console=tts/0,115200n8" to the kernel, I don't get any
>>console output until the login prompt which I set to 115200 in
>>/etc/inittab. When I don't pass "console=" option to the kernel, I get
>>console output all the way until "Freeing unused kernel memory:" and the
>>console output is garbled and I don't see any login prompt. Here is the
>>/dev/* content:
>
>
> I don't know exactly what I am talking about right now, but the string
"tts/0"
> in the console-line sounds suspicious to me. AFAIK when using devfs still
> device names on the kernel-commandline have to be old-style.
> Just a guess: try using "console=ttyS0,115200n8" and see if this helps.
>
Yes, but PQ2FADS use cpm_uart and hence the commandline should be
console=ttyCPM0,115200

> Greetings,
>


--
Sincerely,
Vitaly