Re: [PATCH 1/3] meta/classes: Generate a custom initramfs

[Gylstorff Quirin <quirin.gylstorff@siemens.com>]

On 3/27/20 2:27 PM, Q. Gylstorff wrote:
> From: Quirin Gylstorff <quirin.gylstorff@siemens.com>
> 
> This class sets the Parameters for mkinitramfs before it overwrites
>   the initrd.img of debian with a modified version.
> 
> Use cases are the remove unnecessary kernel modules to reduce the
> size of the initrd by using the parameters:
> ```
> INITRAMFS_MODULES = "list"
> INITRAMFS_MODULE_LIST += "ext4"
> ```
> 
> Set the boot root during the initrd generation by setting `INITRAMFS_ROOT`.
> 
> see also man pages of mkinitramfs and initramfs.conf.
> 
> Signed-off-by: Quirin Gylstorff <quirin.gylstorff@siemens.com>
> ---
>   meta/classes/initramfs.bbclass | 44 ++++++++++++++++++++++++++++++++++
>   1 file changed, 44 insertions(+)
>   create mode 100644 meta/classes/initramfs.bbclass
> 
> diff --git a/meta/classes/initramfs.bbclass b/meta/classes/initramfs.bbclass
> new file mode 100644
> index 0000000..0cc91c2
> --- /dev/null
> +++ b/meta/classes/initramfs.bbclass
> @@ -0,0 +1,44 @@
> +# This software is a part of ISAR.
> +# Copyright (C) 2020 Siemens AG
> +#
> +# SPDX-License-Identifier: MIT
> +
> +INITRAMFS_MODULES ?= "most"
> +INITRAMFS_BUSYBOX ?= "auto"
> +INITRAMFS_COMPRESS ?= "gzip"
> +INITRAMFS_KEYMAP ?= "n"
> +INITRAMFS_NET_DEVICE ?= ""
> +INITRAMFS_NFSROOT ?= "auto"
> +INITRAMFS_RUNSIZE ?= "10%"
> +INITRAMFS_ROOT ?= ""
> +INITRAMFS_MODULE_LIST ?= ""
> +update_initramfs_modules() {
> +   for modname in ${INITRAMFS_MODULE_LIST}; do
> +     sudo -E tee --append '${ROOTFSDIR}/etc/initramfs-tools/modules' << EOF
> +${modname}
> +EOF
> +   done
> +}
> +update_initramfs_config() {
> +    sudo -E tee ${ROOTFSDIR}/etc/initramfs-tools/initramfs.conf << EOF
> +MODULES=${INITRAMFS_MODULES}
> +BUSYBOX=${INITRAMFS_BUSYBOX}
> +COMPRESS=${INITRAMFS_COMPRESS}
> +KEYMAP=${INITRAMFS_KEYMAP}
> +DEVICE=${INITRAMFS_NET_DEVICE}
> +NFSROOT=${INITRAMFS_NFSROOT}
> +RUNSIZE=${INITRAMFS_RUNSIZE}
> +ROOT=${INITRAMFS_ROOT}
> +EOF
> +}
> +
> +do_update_initramfs() {
> +  update_initramfs_modules
> +  update_initramfs_config
> +  export KERNEL_VERSION=$(ls ${ROOTFSDIR}/lib/modules)
> +  bbplain kernel_version: ${KERNEL_VERSION}
> +  sudo -E chroot '${ROOTFSDIR}' \
> +      mkinitramfs -v -k -o /boot/initrd.img-${KERNEL_VERSION} ${KERNEL_VERSION}

An alternative here would be dracut[1] which has a  nice cmdline and don 
need to copy all the information into the rootfs to generate the 
initramfs. But we would leave the debian way and if want to update the 
kernel/initrd with packages we need the debian scripts.
> +}
> +
> +addtask update_initramfs before do_copy_boot_files after do_rootfs_install
> 
[1]: https://dracut.wiki.kernel.org/index.php/Main_Page
-- 
Quirin