Debug UART for arm64 ?

[Leo Yan]

Hi,

On Sat, Sep 26, 2015 at 03:24:35PM +0900, Masahiro Yamada wrote:
> Forgive me if I am asking a silly question.
> 
> 
> I will have to port ARM64 Linux on our new SoC.
> This is my first work on ARM64 Linux,
> so I have no experience with it yet.
> 
> When I worked on ARM32 Linux porting for the first time,
> lowlevel-debug UART (CONFIG_DEBUG_LL) was very useful for me.
> 
> With my quick search under arch/arm64/ directory,
> I could not find an equivalent one for ARM64.
> 
> 
> Is debug UART available for ARM64?
> Or, is there any other recommended easy-to-use debug facility
> when something like a JTAG-debugger is unavailable.

drivers/tty/serial/earlycon.c is like what you are looking for.

Thanks,
Leo Yan