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

[Henning Schild <henning.schild@siemens.com>]

Am Mon, 30 Mar 2020 09:25:34 +0200
schrieb "[ext] 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.

I think i would stick with the debian way of things. But changing that
config outside a package is a strong violation of Isar best practices.
IMHO not acceptable the way you propose it here.

Whatever gets done should happen automagically on a regular update of
the kernel package.

That said i think that class needs to append a config-package to
IMAGE_INSTALL. The tricky bit will be getting PN/PV etc right, that
might need to contain the image PN/PV to not create false-sharing in
multiconfig.

Henning

> > +}
> > +
> > +addtask update_initramfs before do_copy_boot_files after
> > do_rootfs_install 
> [1]: https://dracut.wiki.kernel.org/index.php/Main_Page