Low level debugging using CONFIG_EARLY_PRINTK=y, omap-debug branch removed

Low level debugging using CONFIG_EARLY_PRINTK=y, omap-debug branch removed

[Tony Lindgren]

Hi all,

Recent commit 93fd03a8c6728b58879f8af20ffd55d9c32a778b added
support for CONFIG_EARLY_PRINTK on ARM. Recent earlier kernels
should work too by applying the patch in the commit above.

This means we can now get rid of the old printk.c hack in the
omap-debug branch, so I've deleted that branch.

To use the earlyprintk, just do the following:

1. Make sure you have the necessary .config options set

CONFIG_DEBUG_LL=y
CONFIG_EARLY_PRINTK=y
CONFIG_OMAP_LL_DEBUG_UART1=y
# CONFIG_OMAP_LL_DEBUG_UART2 is not set
# CONFIG_OMAP_LL_DEBUG_UART3 is not set

The LL_DEBUG_UART above is typically 1, but it's 3 on Nokia
boards.

2. Edit the kernel CMDLINE in your .config to have "debug earlyprintk"

Optionally if you have a JTAG console, you can use CONFIG_DEBUG_ICEDCC
instead LL_DEBUG_UART.

I've also added these instructions to:

http://www.elinux.org/Debugging_OMAP_kernel

Regards,

Tony

RE: Low level debugging using CONFIG_EARLY_PRINTK=y, omap-debug branch removed

[Shilimkar, Santosh]

Tony,
> -----Original Message-----
> From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-owner@vger.kernel.org] On Behalf Of Tony
> Lindgren
> Sent: Wednesday, December 16, 2009 6:24 AM
> To: linux-omap@vger.kernel.org
> Subject: Low level debugging using CONFIG_EARLY_PRINTK=y, omap-debug branch removed
> 
> Hi all,
> 
> Recent commit 93fd03a8c6728b58879f8af20ffd55d9c32a778b added
> support for CONFIG_EARLY_PRINTK on ARM. Recent earlier kernels
> should work too by applying the patch in the commit above.
> 
> This means we can now get rid of the old printk.c hack in the
> omap-debug branch, so I've deleted that branch.
> 
> To use the earlyprintk, just do the following:
> 
> 1. Make sure you have the necessary .config options set
> 
> CONFIG_DEBUG_LL=y
> CONFIG_EARLY_PRINTK=y
> CONFIG_OMAP_LL_DEBUG_UART1=y
> # CONFIG_OMAP_LL_DEBUG_UART2 is not set
> # CONFIG_OMAP_LL_DEBUG_UART3 is not set
> 
> The LL_DEBUG_UART above is typically 1, but it's 3 on Nokia
> boards.
> 
> 2. Edit the kernel CMDLINE in your .config to have "debug earlyprintk"
> 
> Optionally if you have a JTAG console, you can use CONFIG_DEBUG_ICEDCC
> instead LL_DEBUG_UART.
> 
> I've also added these instructions to:
> 
> http://www.elinux.org/Debugging_OMAP_kernel
I tried this on couple of boards and at least it doesn't work with the options and mentioned bootargs. The low level debug prints are still not coming on console.

I haven't debugged it though.

Regards,
Santosh

RE: Low level debugging using CONFIG_EARLY_PRINTK=y, omap-debug branch removed

[Paul Walmsley]

On Wed, 16 Dec 2009, Shilimkar, Santosh wrote:

> I tried this on couple of boards and at least it doesn't work with the 
> options and mentioned bootargs. The low level debug prints are still not 
> coming on console.
> 
> I haven't debugged it though.

It works on Beagle, at least.  That's the only one that I've tested so 
far.

If you're using the kernel commandline from u-boot, don't forget to update 
it.


- Paul

Re: Low level debugging using CONFIG_EARLY_PRINTK=y, omap-debug branch removed

[Kevin Hilman]

Paul Walmsley <paul@pwsan.com> writes:

> On Wed, 16 Dec 2009, Shilimkar, Santosh wrote:
>
>> I tried this on couple of boards and at least it doesn't work with the 
>> options and mentioned bootargs. The low level debug prints are still not 
>> coming on console.
>> 
>> I haven't debugged it though.
>
> It works on Beagle, at least.  That's the only one that I've tested so 
> far.
>

I've been using the earlyprink patch for PM debug on several OMAP3
boards without any problems.

Kevin