Research kernel debug boot process

[bschwand]

Hi all,

 

Is there some documentation or How To on how to debug the boot process ? I posted before I am trying to bring up a AW-SOM-A20 board that gets stuck at boot. I am kind of at a loss so I figure next step is to use the kernel debugger, which I have never done on linux (I have experience with darwin/mac OS and freebsd though)

 

Is there a build option for armbian so that the debuggable kernel image is left around in the build process ?

 

All help appreciated, thanks

 

Bruno

[Igor]

1 minute ago, bschwand said:

so that the debuggable kernel image is left around in the build process ?

This goes beyond Armbian. Our tools will make this process of rebuilding images/kernel smoother, but the hard job is still on you. You can find a problem in minutes, days or weeks. There is nobody that could step in and do this time instead of you. The same time gamble stands for experienced people. You have to enable kernel debugging, tracing, ... kernel debugging is not Armbian specifics.

 

6 minutes ago, bschwand said:

Is there some documentation or How To on how to debug the boot process

 

Most of the usable stuff regarding Allwinner hardware you will find here https://linux-sunxi.org and by searching our forums.

[Igor]

24 minutes ago, bschwand said:

I am trying to bring up a AW-SOM-A20

Closely inspect board device tree blobs (u-boots and kernels) and u-boot config if they match reality. Drivers to support A20 hardware are mainly good functional.

[bschwand]

57 minutes ago, Igor said:

This goes beyond Armbian. Our tools will make this process of rebuilding images/kernel smoother, but the hard job is still on you. You can find a problem in minutes, days or weeks. There is nobody that could step in and do this time instead of you. The same time gamble stands for experienced people. You have to enable kernel debugging, tracing, ... kernel debugging is not Armbian specifics.

 

 

Most of the usable stuff regarding Allwinner hardware you will find here https://linux-sunxi.org and by searching our forums.

 

yes, I understand that but I am wondering how the armbian devs work in general... since the build process is quite streamlined, I imagined that there exists some tweaks and useful flags so just the kernel or modules can be incrementally built and setup for debugging. I am certainly not the first to want to do kernel debug on armbian build so I am just asking anybody experienced to share his workflow

[Igor]

3 hours ago, bschwand said:

I imagined that there exists some tweaks and useful flags so just the kernel or modules can be incrementally built and setup for debugging

That part is not very well developed. I have an idea to implement such switch but its just an idea. The only useful developer friendly feature is CREATE_PATCHES="yes"

• set to “yes” will prompt you right before the compilation starts to make changes to the source code. Separate for u-boot and kernel. It will also create a patch out of this. If you want that this patch is included in the normal run, you need to copy it to appropriate directory
• set to “no” compilation will run uninterrupted

But this is not a debug features. We provide build logs and that's about it.

The rest are kernel features, which you enable with KERNEL_CONFIGURE="yes" ... but you have to know what to enable and which tools to use to get going ...