implementing "suspend to ram" on cortex A8 based on linux 3.0.8

Barry Song 21cnbao at
Tue Mar 13 14:34:18 UTC 2012

hi yang,

在 2012年3月10日 下午10:37,yang gqyang <hustgqyang at> 写道:
>  Thanks for your comment.
>  Finally, i find out that i made a mistake.  The uart(8250) have not been
>  restore after resume, instead, it use the configuration got from boot. The
>  uart have not been restored correctly, so that "ls" can not output result
>  correctly resulting in it seems that the busybox can not work correctly.
>  Now, i still have a question about the uart: why the "printk" can work
>  correctly, but the "printf" not?
>  Before this, i believe that the "printk" work correctly, then the uart
>  work ok. but now, i  need more reconsidaration about
>  the relation between the "printk", "printf" and "uart".
>  Can anyone give me some suggestion? Any comment is welcome, thanks a
>  lot.

printk use "struct console" driver, it doesn't depend on a device node
for userspace.
printf actaully depends on uart_driver and a /dev/ttySx device node,
stdout and stderr are redirected to /dev/ttySx
uart is just a hardware which can be a tty or kernel console output.


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