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Old 06-24-2009
Interloper Interloper is offline
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Join Date: Jun 2009
Location: Freising, Germany
Posts: 3
Post Porting Linux and TTY / Shell problems

Hello all,

I am porting the linux 2.6.30rc2 kernel from one ARM architecture, /arch/arm/mach-davinci, to a new device, called Jacinto2.

I am using the serial port ttyS0 as the default console. The bootloader is U-Boot and I am using busybox mounted as a ramdisk in internal SDRAM. I have got the kernel to the point where it will boot into the shell, however at this point I experience a weird error.

The kernel displays the '/# ' shell prompt, but the shell cannot take keyboard input. It will not react to any key presses, but can display text.

However, the serial interrupt functions properly, and if I use printk's to print the serial buffer (in function uart_insert_char in /include/linux/serial_core.h), it outputs the characters I type.

I'm pretty sure my busybox fs works fine, because when I pass init=/bin/ls (redirects to busybox.ls), I can see my fs properly, and passing a simple hello world program (init=/hello) outputs text like I expect.

I feel like somehow the tty_buffer is not passing the characters to the shell. I've determined that the characters are being stored in the "tty_buffer" struct. As I keep typing, the buffer fills up with these chars (In the tty_insert_flip_char function in /include/linux/tty_flip.h) but never empties.

Am I mistaken, or should this be cleared as the chars are flushed to the user space? Also, does anyone know how the tty passes its buffer to user space programs such as the shell?

Has anyone seen this before or have suggestions to try?

Thanks,
Joe


---------Log--------------------
...
RAMDISK: gzip image found at block 0
EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended
VFS: Mounted root (ext2 filesystem) on device 1:0.
Freeing init memory: 144K
uart_open(0) called
ttyS0 - using backup timer
*** trying init processes: </bin/sh>
*** run_init_process(/bin/sh)
/#
--------------------------------
at this point, my printk's/serial IRQ's will work, but the shell doesn't react to keyboard input