The latest versions of the kernel require elfutils to be able to compile.
scu install elfutils
Building a kernel version and deploying it to the proper directories so that it can be used by the proper boot loader can be achieved using the following command:
MAJOR=5.x MINOR=5.17.4 VARIANT=basic DEPLOY=1 kernel.build
To install a previously build kernel image (and modules) avoiding the rebuilding of the kernel one should be connected with the target repository and the issue:
VARIANT=large VERSION=latest kernel.install
Special versions of the kernel exist for the ARM process environment specially for usage under the Raspberry Pi infra-structure for that the crosstool toolchain is required:
scu install crosstool-rasp KARCH=arm \ KTARGET=/opt/arm-rasp-linux-gnueabihf/bin/arm-rasp-linux-gnueabihf \ VARIANT=rasp \ DEPLOY=1 \ kernel.build
To build the kernel optimized for Raspberry Pi 2 use VARIANT=rasp2.
The upgrading operation may be a complex one as it involves changing the configuration files.
For some of the files (eg: large and basic) it might be interesting to use the Ubuntu config files stored in /boot/config-xxx-generic as a reference in the construction of them. For that install Ubuntu in a VM and then use Ukuu to upgrade the kernel to desired version.
An alternative way of building a base .config file from the Ubuntu distribution one is to download the linux-modules-*.deb file from the https://kernel.ubuntu.com/~kernel-ppa/mainline/ repository and then extract the config file from it.
It may also be interesting to "port" the blacklisted modules from the Ubuntu distribution at /etc/modprobe.d/blacklist-*.conf.
For the Ubuntu configuration to work under Scudum environment these extra directives must be included:
CONFIG_BLK_DEV_RAM=y CONFIG_USB_STORAGE=y
Ensuring that proper CD-ROM and HD support is granted these lines should be added:
CONFIG_ISO9660_FS=y CONFIG_UDF_FS=y CONFIG_SATA_AHCI=y CONFIG_NLS_ASCII=y CONFIG_NLS_ISO8859_1=y CONFIG_NLS_UTF8=y
Other than these the basic ones referred in the Raspberry Pi Configuration should also be included.
In order to use some of the drivers custom and proprietary firmware may be required. The best way to update these same package is to use the pre-compiled Ubuntu packages here.
The newly created firmware package should be placed here. Whenever a new package is created a merged with the previous one should be done.
The Raspberry Pi should have a special (smaller) firmware package retrieved from the Raspbian image file from the download website.