how to debug Linux kernel boot process after turn MMU on stage [ I tried linux-arm-kernel mailing list arch workaround but issue]

[Russell King - ARM Linux]

On Mon, Sep 24, 2012 at 02:32:49PM +0530, Tryout check wrote:
> Hi,
> 
> 
> I am trying to Boot Linux kernel 3.0.1 on a custom hardware.
> 
> I am able to debug the Linux Kernel 3.0.1 boot process till
> __enable_mmufunction defined in head.S, using serial port.
> 
> But as soon as __turn_mmu_on function is performed I am not able to debug
> the boot process.
> 
> I have gone through linux-arm-kernel mailing list archives & i have tried
> their printascii() work around. But still I am not able to see any boot
> logs on serial console after __turn_mmu_on.
> 
> Here I am able to get logs before __turn_mmu_on so my serial console port
> is working fine.
> 
> And one more thing - I don't have JTAG.
> 
> Can anyone provide the solution how to debug Linux kernel Boot process
> after turn MMU on?
> 
> Thank you for the support.

Please post to the linux-arm-kernel list.

Debugging in this area is extremely fraught to the extreme.  Most peoples
attempts at debugging this result in total failure (as yours is) because
their debugging code creates more problems than it solves.

Moreover, using debuggers in this area also seems to cause more problems.

The advice I've always given people is: remove all your debugging, and
check whether you get into the C code - start_kernel().  Most people who
do that are surprised, because they find that they are getting there.

That's because the early assembly code has been well tested over the
years and is almost never a problem.  To reiterate the point - most
problems in this code come down to people modifying it through their
own "debugging" attempts.