Re: [PATCH L-C v2 7/7] linux-custom: rewrite to no longer depend on the kernel's builddeb

[Cedric Hombourger <chombourger@gmail.com>]

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On Sat, 9 Nov 2019 at 09:51, Jan Kiszka <jan.kiszka@siemens.com> wrote:

> On 07.11.19 10:23, Cedric Hombourger wrote:
> > Regain control over the packaging of the Linux kernel by providing our
> > own debian recipes (debian,{control,rules} files and friends) instead
> > of using the kernel's builddeb script. This will allow generation of
> > packages for "perf" (not included in this changeset) with per distro
> > scheme (Debian and Ubuntu have differences) and maintain compatibility
> > with upstream packages generated from different source packages but
> > dependent on a certain deployment scheme (e.g. linux-base for Debian)
> >
> > Signed-off-by: Cedric Hombourger <Cedric_Hombourger@mentor.com>
> > ---
> >   doc/custom_kernel.md                          | 181 ++++++++++++++++
> >   .../linux/files/build-kernel.sh               | 128 -----------
> >   meta/recipes-kernel/linux/files/debian/compat |   1 +
> >   .../linux/files/debian/control.tmpl           |  37 ++++
> >   .../linux/files/debian/isar/build.tmpl        |  36 ++++
> >   .../linux/files/debian/isar/clean.tmpl        |  20 ++
> >   .../linux/files/debian/isar/common.tmpl       |  48 +++++
> >   .../linux/files/debian/isar/install.tmpl      | 204 ++++++++++++++++++
> >   .../files/debian/linux-image.postinst.tmpl    |  29 +++
> >   .../files/debian/linux-image.postrm.tmpl      |  35 +++
> >   .../files/debian/linux-image.preinst.tmpl     |  25 +++
> >   .../linux/files/debian/linux-image.prerm.tmpl |  21 ++
> >   .../linux/files/debian/rules.tmpl             |  41 ++++
> >   meta/recipes-kernel/linux/linux-custom.inc    | 179 ++++++++++-----
> >   14 files changed, 800 insertions(+), 185 deletions(-)
> >   create mode 100644 doc/custom_kernel.md
> >   delete mode 100644 meta/recipes-kernel/linux/files/build-kernel.sh
> >   create mode 100644 meta/recipes-kernel/linux/files/debian/compat
> >   create mode 100644 meta/recipes-kernel/linux/files/debian/control.tmpl
> >   create mode 100644
> meta/recipes-kernel/linux/files/debian/isar/build.tmpl
> >   create mode 100644
> meta/recipes-kernel/linux/files/debian/isar/clean.tmpl
> >   create mode 100644
> meta/recipes-kernel/linux/files/debian/isar/common.tmpl
> >   create mode 100644
> meta/recipes-kernel/linux/files/debian/isar/install.tmpl
> >   create mode 100644
> meta/recipes-kernel/linux/files/debian/linux-image.postinst.tmpl
> >   create mode 100644
> meta/recipes-kernel/linux/files/debian/linux-image.postrm.tmpl
> >   create mode 100644
> meta/recipes-kernel/linux/files/debian/linux-image.preinst.tmpl
> >   create mode 100644
> meta/recipes-kernel/linux/files/debian/linux-image.prerm.tmpl
> >   create mode 100755 meta/recipes-kernel/linux/files/debian/rules.tmpl
> >
> > diff --git a/doc/custom_kernel.md b/doc/custom_kernel.md
> > new file mode 100644
> > index 0000000..934325a
> > --- /dev/null
> > +++ b/doc/custom_kernel.md
> > @@ -0,0 +1,181 @@
> > +# Custom kernel recipe for Isar
> > +
> > +## Contents
> > +
> > + - [Summary](#summary)
> > + - [Proposal owners](#proposal-owners)
> > + - [Current status](#current-status)
> > + - [Detailed description](#detailed-description)
> > + - [Benefit to Isar](#benefit-to-isar)
> > + - [How can I help?](#how-can-i-help)
> > + - [Scope](#scope)
> > + - [How to test](#how-to-test)
> > + - [Dependencies](#dependencies)
> > + - [Documentation](#documentation)
> > + - [Questions and answers](#questions-and-answers)
> > +
> > +## Summary
> > +
> > +Isar currently uses the Linux kernel's builddeb script to generate
> linux-image,
> > +linux-headers and linux-libc-dev packages for your custom kernel
> sources. The
> > +main benefit of this approach was that the low level details of how to
> package
> > +the Linux kernel image, modules and headers were left in the kernel.
> There are
> > +however some drawbacks: Isar had to repack generated packages to
> introduce some
> > +of the changes it needs such as suffixing the kernel packages with the
> name of
> > +the custom kernel (e.g. with "mainline" for the "linux-mainline"
> recipe), lack
> > +of automatic dependencies (the builddeb script from the kernel does not
> use
> > +debhelper), it was difficult to add packages especially distribution
> specific
> > +packages (maintain version specific patch in Isar vs being able to
> upstream
> > +distribution specific changes upstream), etc. This change is about
> being less
> > +dependent on the kernel packaging scripts (which aren't used by major
> distros
> > +anyway) and regain control on how we want or need the Linux kernel
> packaged.
> > +
> > +## Proposal owners
> > +
> > + * name: [Cedric Hombourger](https://github.com/chombourger)
> > +
> > +## Current status
> > +
> > +### Tests
> > +
> > +The following were recently checked:
> > +
> > + * Custom kernels in meta-isar build without (known) failures
> > + * initrd image gets generated when the kernel is added to the rootfs
> > + * `ISAR_CROSS_COMPILE` is supported
> > + * `KERNEL_FILE` is honored
> > + * `KERNEL_DEFCONFIG` may either be a file (specified via `SRC_URI`) or
> a
> > +   kernel-provided defconfig
> > + * Config fragments get merged with the user-specified kernel
> configuration
> > + * Path to installed DTBs may be configured (new)
> > + * Configuration and build from a `devshell`
> > + * Support for the `KERNEL_LIBC_DEV_DEPLOY` directive
> > +
> > +while the following needs work:
> > +
> > + * Check if custom-kernel builds are reproducible
> > +
> > +### Remaining work items
> > +
> > + * Check if there is a better way to cross compile kernel "scripts"
> such as
> > +   `fixdep` or `modpost` than manually compiling them (they are
> compiled for
> > +   the build machine (amd64) and not for the target (e.g. armhf) even
> though
> > +   we are cross-compiling - yet the linux-headers package should be
> shipping
> > +   "scripts" for the target machine)
> > +
> > +## Detailed description
> > +
> > +### Requirements
> > +
> > +#### Current
> > +
> > +Isar has had a `linux-custom` recipe for a long time and counts many
> users. It is therefore
> > +paramount to maintain features that it has today with no or little
> changes to the APIs. The
> > +following requirements were identified and will be maintained:
> > +
> > + 1. Sources to the custom Linux kernel may be specified via `SRC_URI`
> > +
> > + 2. Configure the kernel via an in-tree or an external `defconfig` via
> `KERNEL_DEFCONFIG`
> > +
> > + 3. Support kernel configuration tweaks via configuration fragments
> (`.cfg` files)
> > +
> > + 4. Patches to the linux kernel may be specified via `SRC_URI`
> > +
> > + 5. Ensure that the Isar recipe `PV` matches the kernel release
> identifier (`KERNEL_RELEASE`)
> > +
> > + 6. Produce a `linux-image` package that ships the kernel image and
> modules
> > +
> > + 7. Allow the name of the kernel image to be changed via `KERNEL_FILE`
> (defaults to `vmlinuz`)
> > +
> > + 8. Produce a `linux-headers` package which includes kernel headers and
> kbuild scripts/tools
> > +
> > + 9. The `linux-headers` package shall support native and cross compiles
> of out-of-tree kernel modules
> > +
> > + 10. Produce a `linux-libc-dev` package to support user-land builds
> > +
> > + 11. Only ship the `linux-libc-dev` package if instructed to
> (`KERNEL_LIBC_DEV_DEPLOY` equals to `"1"`)
> > +
> > + 12. Support both native and cross compiles (`ISAR_CROSS_COMPILE`)
> > +
> > + 13. Support for the following kernel architectures:
> > +
> > +   * arm
> > +   * arm64
> > +   * mips
> > +   * x86
> > +
> > + 14. Support `devshell` (kernel configuration shall be applied)
> > +
> > +#### New requirements (proposed)
> > +
> > +This proposal includes the following new requirements:
> > +
> > + 1. Support creation of additional packages
> > +
> > + 2. Allow per-distro packaging tweaks
> > +
> > +### Approach
> > +
> > +The new implementation will have the `builddeb` code ported from the
> Linux kernel included to the
> > +Isar environment. It will be refactor to support pre and post hooks.
> Hooks may be used by external
> > +layers to extend the kernel packaging instructions provided by "stock"
> Isar or by Isar itself to
> > +implement distro-specific packages or tweaks.
> > +
> > +Hooks need the ability to add `build` and `install` steps which can be
> achieved by having the main
> > +`build` and `install` steps call pre and post scripts. This will
> however solve only one side of the
> > +problem: new packages should be declared in the `debian/control` file.
> The packaging process
> > +(initiated by `debian/rules`) will use a baseline `control` file when
> started and a mechanism will
> > +be provided for hooks to append `control` blocks as they are processed.
> > +
> > +### Future work
> > +
> > +In the event where this proposal is accepted, here are a few future
> projects that are being
> > +considered:
> > +
> > + 1. Package `perf` as Debian does
> > +
> > + 2. Add `ubuntu` as an Isar supported target distro and validate
> `linux-custom` recipe
> > +
> > +## Benefit to Isar
> > +
> > + * Control the kernel build and packaging process
> > +
> > + * No longer need to repack packages
> > +
> > + * Provide hooks for custom kernel recipes to add build/install
> directives
> > +
> > +## How can I help?
> > +
> > + * Check if you are able to build your own linux-custom recipes with
> this change
> > + * Check if packages generated by this recipe are compatible with your
> Debian-based distro
> > + * Review and provide comments on this changeset
> > + * Create templates for distro-specific packages (e.g. perf)
> > +
> > +## Scope
> > +
> > + * Proposal owners: proposal owners are to communicate the idea to
> isar-users and make sure
> > +   that all of their requirements are met (to the extent they are
> already supported with the
> > +   current solution) or may be met in the future.
> > +
> > + * Other developers: port your out-of-tree linux-custom recipes to this
> new solution and
> > +   report issues.
> > +
> > +## How to test?
> > +
> > +The linux-mainline recipe may be used for some basic testing. This
> recipe is being used by the
> > +following machines:
> > +
> > + * de0-nano-soc
> > + * qemumipsel
> > +
> > +## Dependencies
> > +
> > + * None
> > +
> > +## Documentation
> > +
> > + * Document user-visible variables added by this proposal
> > +
> > +## Questions and answers
> > +
> > + * None
> > diff --git a/meta/recipes-kernel/linux/files/build-kernel.sh
> b/meta/recipes-kernel/linux/files/build-kernel.sh
> > deleted file mode 100644
> > index f56e96c..0000000
> > --- a/meta/recipes-kernel/linux/files/build-kernel.sh
> > +++ /dev/null
> > @@ -1,128 +0,0 @@
> > -#!/bin/bash
> > -#
> > -# Custom kernel build
> > -#
> > -# This software is a part of ISAR.
> > -# Copyright (c) Siemens AG, 2018
> > -#
> > -# SPDX-License-Identifier: MIT
> > -
> > -source /isar/common.sh
> > -
> > -host_arch=$(dpkg --print-architecture)
> > -
> > -if [ "$host_arch" != "$target_arch" ]; then
> > -    case $target_arch in
> > -    armhf)
> > -        export ARCH=arm
> > -        export CROSS_COMPILE="arm-linux-gnueabihf-"
> > -        ;;
> > -    arm64)
> > -        export ARCH=arm64
> > -        export CROSS_COMPILE="aarch64-linux-gnu-"
> > -        ;;
> > -    mipsel)
> > -        export ARCH=mips
> > -        export CROSS_COMPILE="mipsel-linux-gnu-"
> > -        ;;
> > -    *)
> > -        echo "error: unsupported architecture ($target_arch)"
> > -        exit 1
> > -        ;;
> > -    esac
> > -fi
> > -
> > -REPACK_DIR="$1/../repack"
> > -REPACK_LINUX_IMAGE_DIR="${REPACK_DIR}/linux-image"
> > -REPACK_LINUX_HEADERS_DIR="${REPACK_DIR}/linux-headers"
> > -
> > -make ${KERNEL_CONFIG_TARGET} || exit ${?}
> > -if [ -n "${KERNEL_FRAGMENTS}" ]; then
> > -    scripts/kconfig/merge_config.sh -m .config ${KERNEL_FRAGMENTS}
> > -fi
> > -
> > -KV=$( make -s kernelrelease )
> > -if [ "${KV}" != "${PV}" ]; then
> > -     echo "ERROR: Recipe PV is \"${PV}\" but should be \"${KV}\"" 1>&2
> > -     echo "ERROR: Probably due to CONFIG_LOCALVERSION" 1>&2
> > -     exit 1
> > -fi
> > -
> > -rm -f .version
> > -KBUILD_DEBARCH=$target_arch make -j $(($(nproc) * 2)) deb-pkg
> > -
> > -rm -rf "${REPACK_DIR}"
> > -mkdir -p "${REPACK_DIR}"
> > -mkdir -p "${REPACK_LINUX_IMAGE_DIR}"
> > -mkdir -p "${REPACK_LINUX_HEADERS_DIR}"
> > -
> > -cp -a debian "${REPACK_DIR}"
> > -
> > -# dpkg-gencontrol performs cross-incompatible checks on the
> > -# Architecture field; trick it to accept the control file
> > -sed -i "s/Architecture: .*/Architecture: any/"
> "${REPACK_DIR}/debian/control"
> > -
> > -cd ..
> > -
> > -dpkg-deb -R linux-image-${PV}_${PV}-1_*.deb "${REPACK_LINUX_IMAGE_DIR}"
> > -dpkg-deb -R linux-headers-${PV}_${PV}-1_*.deb
> "${REPACK_LINUX_HEADERS_DIR}"
> > -
> > -dpkg-gencontrol -crepack/debian/control \
> > -     -lrepack/debian/changelog \
> > -     -frepack/debian/files \
> > -     -plinux-image-${PV} \
> > -     -P"${REPACK_LINUX_IMAGE_DIR}" \
> > -     -DPackage="linux-image-${KERNEL_NAME}" \
> > -     -DSection=kernel \
> > -     -DPriority=required \
> > -     -DDepends="${KERNEL_DEBIAN_DEPENDS}" \
> > -     -DArchitecture=$target_arch
> > -
> > -# Add Debian-like link installation to postinst
> > -mkdir -p ${REPACK_LINUX_IMAGE_DIR}/lib/modules/${PV}
> > -touch "${REPACK_LINUX_IMAGE_DIR}/lib/modules/${PV}/.fresh-install"
> > -sed -i "${REPACK_LINUX_IMAGE_DIR}/DEBIAN/postinst" \
> > -    -e "/^set -e$/a\\
> > -\\
> > -if [ -f /lib/modules/${PV}/.fresh-install ]; then\\
> > -     change=install\\
> > -else\\
> > -     change=upgrade\\
> > -fi\\
> > -linux-update-symlinks \$change ${PV} /boot/${KERNEL_FILE}-${PV}\\
> > -rm -f /lib/modules/${PV}/.fresh-install"
> > -
> > -# Add Debian-like link removal to postrm
> > -sed -i "${REPACK_LINUX_IMAGE_DIR}/DEBIAN/postrm" \
> > -    -e "/^set -e$/a\\
> > -\\
> > -rm -f /lib/modules/${PV}/.fresh-install\\
> > -\\
> > -if [ \"\$1\" != upgrade ] && command -v linux-update-symlinks
> >/dev/null; then\\
> > -     linux-update-symlinks remove ${PV}  /boot/${KERNEL_FILE}-${PV}\\
> > -fi"
> > -
> > -# Make sure arm64 kernels are decompressed
> > -if [ "$target_arch" = "arm64" ]; then
> > -     kernel_file="${REPACK_LINUX_IMAGE_DIR}/boot/${KERNEL_FILE}-${PV}"
> > -     mv "${kernel_file}" "${kernel_file}.gz"
> > -     gunzip "${kernel_file}.gz"
> > -fi
>
> Next regression: This got lost.
>

Fixed locally (
https://github.com/chombourger/isar-fork/blob/cedric/next/meta/recipes-kernel/linux/files/debian/isar/install.tmpl#L62
)
Started a test build to check

Thanks for catching that subtle one


>
> Jan
>
> --
> Siemens AG, Corporate Technology, CT RDA IOT SES-DE
> Corporate Competence Center Embedded Linux
>
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