Subject: A PPC kernel issue with UART ??

From: "JohnsonCheng" <[email-masked]>
Date: Tue, 2 Aug 2005 19:41:41 +0800

Dear All,

I meet a wired UART problem on linux-2.6 with MPC8241 chip.

My Environment is as following: 

CPU: MPC8241

Linux: 2.6.12.3

COM1 offset: 0x4500, COM2 offset: 0x4600

When I booting my rootfs, it hangs at following message:

RAMDISK: Compressed image found at block 0

VFS: Mounted root (ext2 filesystem) readonly.

Freeing unused kernel memory: 104k init

EXT2-fs warning: checktime reached, running e2fsck is recommended

I had add printk in tty_write() of drivers/char/tty_io.c, the message from
rootfs have printed.

The conclusion is that message can be printed by printk() in linux kernel,
but can't be printed by printf() in user mode. I think it must be something
wrong for my UART configurations, does anybody know it??

Best Regards,

Johnson Cheng