Re: printf internals
- From: "Masoud Sharbiani \"مسعود شربیانی\"" <masouds@xxxxxxxxx>
- Date: Wed, 19 Dec 2007 16:04:30 -0800
On 12/19/07, Siva Prasad <sprasad@xxxxxxxxx> wrote:
Yes!... this is a embedded system, and will not have monitor. So, serial
is the default console.
I pass cmdline as "root=/dev/ram rw console=ttyS0,115200"
Adding a CONSOLE=/dev/ttyS0 works for me on both Debian and Redhat;
You also want a inittab entry for console on serial device. (use
google and find it yourself).
cheers,
Masoud
Thanks--
Siva
-----Original Message-----
From: Scott Russell [mailto:catfather@xxxxxxxxxx]
Sent: Wednesday, December 19, 2007 3:31 PM
To: Siva Prasad
Cc: Clemens Koller; David Newall; linux-kernel@xxxxxxxxxxxxxxx
Subject: RE: printf internals
On Wed, 2007-12-19 at 14:33 -0800, Siva Prasad wrote:
Thank you very much for your response Clemens.as it uses the stdout (fd = 1) and write(1, ...) to it.
I tried strace on a regular system. It does not show which tty, etc.,
ramdisk. Kernel boots fine to a point where it starts accessing ramdisk
This is not a student project. I am trying to build my own kernel and
and executes init scripts. From there on nothing gets printed. I did
some debugging and found that prints of user land programs are not
coming to the serial console, while kernel prints are working fine. I
found all the programs getting executed, by placing a printk in execve
routine and printing the arguments.
and see why it is not printing messages from user program. I placed a
So, I wanted to trace down the path from user program to the kernel
printk in drivers/char/tty_io.c:tty_write() and it is not getting called
from my file system. I tried the same thing on my good system (say
regular PC) and it works as expected.
Any clues that can help debug this issue is highly appreciated.
How can I get access to the same printf string inside kernel.
This sounds like you're printing out the serial console instead.
--
Scott <catfather@xxxxxxxxxx>
AIM: BlueCame1
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