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Author Topic: custom kernel for piCore  (Read 2635 times)

Offline cgemenel

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custom kernel for piCore
« on: November 17, 2014, 03:35:02 PM »
Hello to all,

I have built a custom kernel for piCore, and at boot time I get this error:

Kernel panic - not syncing : VFS : Unable to mount root fs on unknown-block(1,0)

as if it does not find the ramfs.

What I did:

- I have built the kernel ( on a virtual machine, not cross compiled )
- I have remastered the ramfs file to include the new kernel modules
- I have copied the kernel.img and ramfs.gz files to the mmcblk0p1 partition
- I have updated the config.txt with the new kernel and ramfs file names
- I have updated the cmdline.txt with the new ramfs size

When I reboot, I get the kernel panic mentioned above.

Anyone has any idea why is this happening?


Offline lykkedk

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Re: custom kernel for piCore
« Reply #1 on: November 17, 2014, 09:22:46 PM »

Which kernel, did you compile?
Did you use existing .config from running piCore?


Offline cgemenel

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Re: custom kernel for piCore
« Reply #2 on: November 17, 2014, 10:06:40 PM »

I was building the piCore-3.13.6 using piCore-3.13.6+.config .
What I need are rndis and cdc modules, and I did not find these modules on tinycore linux site to download for 3.14.4.

Meanwhile, I tried combinations between the kernel compiled by me and the original ramfs image, and then the original kernel and the remastered ramfs image. The second combination boots, so the problem is in the kernel, not in the remastered ramfs image nor in the boot config files.

Since I did not change the config at all ( I just used a make oldconfig ), is it possible that the fact that I built the kernel on a virtual machine to have an impact? ( even if I find it hard to see how.... )


Offline bmarkus

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Re: custom kernel for piCore
« Reply #3 on: November 17, 2014, 11:16:05 PM »

when you have a custom kernel you must update initrd with the matching modules. It is easy to mix up different versions during development and get a not working system, it happenes to me also.

Kindly advice to try 6.0alpha releases with 3.17.x kernel. You can download all modules built with the kernel. Check for your rndis and cdc modules in it and let me know if one is missing:


« Last Edit: November 17, 2014, 11:17:48 PM by bmarkus »
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Offline cgemenel

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Re: custom kernel for piCore
« Reply #4 on: November 18, 2014, 12:18:40 AM »
Hello Béla,

I did update the initrd with the newly built modules ( I just called it ramfs image in my earlier posts).
Nevertheless, even without any correct module the system should have been loaded and get a prompt. - as I tested with the original kernel (3.14.4), and the initrd that I have remastered and which contained only the modules built by me (3.13.6).

It must be something wrong with my build, but I can not imagine what.

Thanks for the link, I will try the 6.0alpha tonight.