Re: Problem dtb file booting Kernel 2.6.32

Hello,

I was able to boot Kernel 2.6.26.8 (using our old dts file from 
Kernel 2.6.25). However, I need to upgrade to a newer Kernel because
I am having serious problems with the ethernet interface under heavy
load. I am not sure if it could be a scheduling problem or the network
driver. CPU usage is low but load average is high (more than 4).

The main difference that I could find is that for newer Kernels the 
/arch/ppc was removed. I also read online that dts version changed 
from 0 to 1 somewhere around Kernel 2.6.27 or so.

Following your instruction, I executed in the LTIB command shell:

LTIB> dtc -I dtb -O dts ../mpc8272ads.dtb

I executed that command passing as argument the old working dtb file.
I got a dts file which I placed in the new Kernel and compiled.
Unfortunately, I am still getting the same error.

Attached you can find both dts files.

Thank you.


-- 
Andres F Marquez
EdgeAccess
Development
amarquez@edgeaccess.net



On Thu, 2010-01-14 at 15:44 -0600, Scott Wood wrote:

Andres F Marquez wrote:

quoted

Hello,

I am working on a MPC8265 board which I have successfully ported Linux
Kernel 2.6.25 to. I am trying to upgrade the Kernel but have not got
good results (I am able to compile the Kernel for my powerpc, but not to
boot it). The problem appears to be something related to the interaction
between the dtb and the Kernel. I am not sure if the syntax for the dts
file may have changed from Kernel 2.6.25 to newer versions (I have tried
2.6.27.43 - 2.6.32.2 and 2.6.31.11 getting very similar results).

Can you bisect between 2.6.25 and 2.6.27 to see which commit may have 
broken it?

What sort of changes did you make to get 2.6.25 to work?

quoted

When I build the dtb file from the /arch/powerpc/boot/dts/MPC8272ADS.dts
file that comes with the new Kernel, the booting process gets stuck
after trying to load the device tree:

	## Booting image at ff810000 ...
   		Image Name:   Linux-2.6.27.43
   		Image Type:   PowerPC Linux Kernel Image (gzip  
			compressed)
		Data Size:    1365263 Bytes =  1.3 MB
   		Load Address: 00000000
   		Entry Point:  00000000
   		Verifying Checksum ... OK
   		Uncompressing Kernel Image ... OK
   		Booting using the fdt at 0xff802000
   		Loading Device Tree to 007fc000, end 007fefff ... OK


   However, when I boot the new Kernel with the old compiled dtb file
(the one that works with the Kernel 2.6.25) the process moves forward
but stops at a time when displaying information about IRQ 40 line
(related to the Programmable Interrup Controller (PIC)):

Decompile that device tree blob using dtc -I dtb -O dts, and look for 
differences.

-Scott