[SOLVED] Raspberry Pi4 how to Kernel upgrade

[ROGA]

Hi,

I could successful install Gentoo on a Raspberry Pi 4 with this guide and this guide.

For my first installation I Fetched the Kernel Version rspi-4.19.y from the Git-Hub Repository and cross-compiled it. All worked well and my Pi could afterwards boot successfully.


Later I saw that there are other branch version of the kernel so I would tried to upgrade the kernel to the version rpi-4.20.y.

I did following on my pc:

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root@gentoo ~/RaspberryPi/linux # git checkout rpi-4.20.y
Checking out files: 100% (12834/12834), done.
Switched to a new branch 'rpi-4.20.y'

then I updated the .config file

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root@gentoo ~/RaspberryPi/linux # ARCH=arm64 CROSS_COMPILE=aarch64-unknown-linux-gnu- make olddefconfig

after that I compiled and installed the new kernel

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root@gentoo ~/RaspberryPi/linux # ARCH=arm64 CROSS_COMPILE=aarch64-unknown-linux-gnu- make -j9
root@gentoo ~/RaspberryPi/linux # cp ~/RaspberryPi/linux/arch/arm64/boot/Image /mnt/gentoo/boot/kernel8.img

and installed the associated kernel-modules.

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root@gentoo ~/RaspberryPi/linux # ARCH=arm64 CROSS_COMPILE=aarch64-unknown-linux-gnu- make modules_install INSTALL_MOD_PATH=/mnt/gentoo

I then put the microSD in my raspberry pi 4 and booted it but it doesn't boot anymore.

Does this branch version not work? Or do I had made a wrong step?

I am very grateful for any information.

[NeddySeagoon]

ROGA,

When you checked out rpi-4.20.y, it came with a new bcm2711_defconfig. You should use that as your starting point.
I don't know what

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ARCH=arm64 CROSS_COMPILE=aarch64-unknown-linux-gnu- make olddefconfig

does inside a git checkout.
If you copy the old .config outside of git, do the checkout, then move the old .config back to the kernel, I would be more confident that make olddefconfig would do what you were expecting.

There is a working rpi-5.4.y branch now too, so its time to migrate to that.

[ROGA]

NeddySeagoon,

I did what you recommended and also migrate to the newest branch version 5.4.y and really it works now!

Thank you very much!!!!!

[ROGA]

Hi NeddySeagoon,

it sems that the new branch kernel version 5.4.y has a problem with the onboard nic. I couldn't see a nic anymore after migration.

I don't have any Idea, how I could solve this problem

lspci and lsusb don't show me a nic-card, stange!

[NeddySeagoon]

ROGA,

It works here. Did you use the correct .dtb?
Only the USB3 is on a PCIe lane. The LAN is on its own Broadcom link.

My Pi4 kernel binary is on my server.

bcm2711-rpi-4-b.dtb_64 is the 64 bit device tree.
kernel-5.4.3-v8+ is the kernel binary.
config.txt sets up things the way I like and loads the above files by name

5.4.3-v8+.tbz2 is a tarball of the kernel modules.
It needs to be untarred to /lib/modules/ on the Pi.

[ROGA]

NeddySeagoon,

It works here.

Good to hear that, I remain confident

Did you use the correct .dtb?

Ohh, I used the same .dtb file as with kernel 4.19.y. I didn't realize that the new kernel version brings a new .dtb file. I did think that this could be the same file for all kernel versions.

That was my problem, thanks for this hint.

Now I have kernel 5.4.y and it works with network. But I had to install the branch kernel 5.4.y from the scratch.

What I need to know is the exact procedure to migrate to newer kernel without losing my old .config

btw: your config.txt file is a great example! That's a good way to handle with multiple kernel version and .dtb files.

[NeddySeagoon]

ROGA,

I start with the bcm2711_defconfig for every kernel as I only make one or two changes.
If you make lots of changes, then in worth preserving your .config outside of git.
Do the git pull or git checkout to update your copy of the repo.
Restore the .config inside the repo
Then

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ARCH=arm64 CROSS_COMPILE=aarch64-unknown-linux-gnu- make oldconfig

to update the .config for the new kernel.

The dtb does not change much but the Pi4 is still new so its important to keep a matching kernel/dtb set.
Mostly, the old dtb will be fine but not always :)

[ROGA]

Thank's NeddySeagoon,

I will try your suggestions the next time, when a new version will be released. For safety I wrote down the steps in my wiki

In the meantime, I now will build my Raspberry Pi 3+ with gentoo. Hopefully it will work too

[NeddySeagoon]

ROGA,

The same userland works on both Pi3s and the Pi4
You need a different kernel and dtb depending on the version.

config.txt understands some filers. bootcode.bin can determine what Pi its running on, so you can make one SD card that will boot on any Pi.
That is left as an exercise for the reader :)

[ROGA]

NeddySeagoon,

so you can make one SD card that will boot on any Pi

hey, that sounds great! I will take on this challenge.