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Participant
Participant
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Registered: ‎04-13-2009

How to enable dev_dbg output on boot?

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Hello,  I'm modifying the xilinxfb.c driver to work with a custom tft lcd controller pcore and I need to see the debug messages when the target board is booting.  I do not know how to enable output of dev_dbg() though. Any help would be appreciated.

 

FYI: I'm working on the ML405 development board with Linux on the PowerPC (ARCH=powerpc)

 

Thanks

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Xilinx Employee
Xilinx Employee
42,562 Views
Registered: ‎09-10-2008

Re: How to enable dev_dbg output on boot?

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http://www.kernel.org/pub/linux/kernel/people/gregkh/lkn/lkn_pdf/ch09.pdf

 

google is your friend.

 

just add debug in to the boot args, "console=ttyX debug root=/dev/ram".

 

I'm trying to remember how well this worked, but don't.

 

Thanks.

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Xilinx Employee
Xilinx Employee
31,831 Views
Registered: ‎09-10-2008

Re: How to enable dev_dbg output on boot?

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I don't do this often, so I'm just telling you what I see from the code.  I usually define DEBUG in the top of the source file for the driver and rebuild.  The #define of DEBUG has to be before the existing #includes so that it will cause the debug to be a printk causing kernel output to the console.

 

You may have to add DEBUG on the kernel command also as I don't remember what console output level is by default.

 

That may not be the exact answer but should help you get it going.

 

Thanks.

 

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Xilinx Employee
Xilinx Employee
31,829 Views
Registered: ‎09-10-2008

Re: How to enable dev_dbg output on boot?

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on the kernel command line (boot args) that is rather than kernel command. 
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Participant
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Registered: ‎04-13-2009

Re: How to enable dev_dbg output on boot?

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How do I specify DEBUG in the bootargs?

 

My current bootargs is:

 

bootargs = "console=ttyUL0 root=/dev/ram";

 

 Thanks!

 

 

 

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Xilinx Employee
Xilinx Employee
42,563 Views
Registered: ‎09-10-2008

Re: How to enable dev_dbg output on boot?

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http://www.kernel.org/pub/linux/kernel/people/gregkh/lkn/lkn_pdf/ch09.pdf

 

google is your friend.

 

just add debug in to the boot args, "console=ttyX debug root=/dev/ram".

 

I'm trying to remember how well this worked, but don't.

 

Thanks.

View solution in original post

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Participant
Participant
31,797 Views
Registered: ‎04-13-2009

Re: How to enable dev_dbg output on boot?

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Thanks John!
Message Edited by jairoscz on 10-14-2009 09:27 AM
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