RE: printf internals


On Wed, 2007-12-19 at 14:33 -0800, Siva Prasad wrote:
Thank you very much for your response Clemens.

I tried strace on a regular system. It does not show which tty, etc., as it uses the stdout (fd = 1) and write(1, ...) to it.

This is not a student project. I am trying to build my own kernel and ramdisk. Kernel boots fine to a point where it starts accessing ramdisk 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.

So, I wanted to trace down the path from user program to the kernel and see why it is not printing messages from user program. I placed a 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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