Re: [PATCH 4/5] Add u-boot script generator

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2018-06-06 13:58, [ext] Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> In order to use upstream U-Boot default envs for booting Isar images, we
> either need an extlinux script - can be provided by Debian u-boot-menu
> from buster - or some boot.scr. The latter has the advantage of skipping
> the interactive stage of a kernel selection, specifically when there is
> only one kernel on an image, and allowing for injection of custom U-Boot
> commands.

BTW, there is also the Debian flash-kernel package with is apparently
also able to generate some boot.scr, using a large device data base.

My impression is that its enormous complexity is related to its history
and the many legacy boards it supports. This rather simple tool should
be sufficient when looking forward and focusing on the modern U-Boot
distro interface. E.g., it's redundant to maintain the device tree name
in the flash-kernel database - u-boot knows it already.

> 
> This package generates the needed boot.scr, using the installed kernel
> package and the rootfs parameters found in the target's /etc/fstab. It
> is able to update itself when the kernel package is changed on the
> target. Further kernel parameters and custom U-Boot commands can be
> configured on the target via /etc/default/u-boot-script. This also
> allows to opt-out from using an initramfs when the kernel does not need
> one to boot properly.
> 
> Furthermore, the package recipe can evaluate and bootloader --append=...
> line from the WKS_FILE used for the target and inject those kernel
> parameters into the deployed /etc/default/u-boot-script.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  meta/recipes-bsp/u-boot-script/files/u-boot-script |  9 ++++
>  .../u-boot-script/files/update-u-boot-script       | 58 ++++++++++++++++++++++
>  .../u-boot-script/files/zz-u-boot-script           |  3 ++
>  .../recipes-bsp/u-boot-script/u-boot-script_1.0.bb | 53 ++++++++++++++++++++
>  4 files changed, 123 insertions(+)
>  create mode 100644 meta/recipes-bsp/u-boot-script/files/u-boot-script
>  create mode 100755 meta/recipes-bsp/u-boot-script/files/update-u-boot-script
>  create mode 100755 meta/recipes-bsp/u-boot-script/files/zz-u-boot-script
>  create mode 100644 meta/recipes-bsp/u-boot-script/u-boot-script_1.0.bb
> 
> diff --git a/meta/recipes-bsp/u-boot-script/files/u-boot-script b/meta/recipes-bsp/u-boot-script/files/u-boot-script
> new file mode 100644
> index 0000000..53cc613
> --- /dev/null
> +++ b/meta/recipes-bsp/u-boot-script/files/u-boot-script
> @@ -0,0 +1,9 @@
> +# Arguments to append to kernel command line.
> +# Make sure to escape $ in u-boot variables, e.g. "\${console}".
> +KERNEL_ARGS_APPEND=""
> +
> +# Set to "yes" or "1" to leave out initrd, even if present
> +NO_INITRD=""
> +
> +# U-boot commands to prepend to boot script
> +SCRIPT_PREPEND=""
> diff --git a/meta/recipes-bsp/u-boot-script/files/update-u-boot-script b/meta/recipes-bsp/u-boot-script/files/update-u-boot-script
> new file mode 100755
> index 0000000..4ce74bb
> --- /dev/null
> +++ b/meta/recipes-bsp/u-boot-script/files/update-u-boot-script
> @@ -0,0 +1,58 @@
> +#!/bin/sh
> +#
> +# Boot script generator for U-Boot
> +#
> +# This software is a part of ISAR.
> +# Copyright (c) Siemens AG, 2018
> +#
> +# SPDX-License-Identifier: MIT
> +
> +set -e
> +
> +if [ -f /etc/default/u-boot-script ]; then
> +	. /etc/default/u-boot-script
> +fi
> +
> +ROOT_PART="\${distro_bootpart}"
> +
> +while read DEV MOUNT_POINT REST; do
> +	if echo ${DEV} | grep -q "^#"; then
> +		continue
> +	fi
> +	if [ "${MOUNT_POINT}" = "/" ]; then
> +		ROOT_DEV=${DEV}
> +		ROOT_PART=$(echo ${DEV} | sed 's/.*[^0-9]\([0-9]*\)$/\1/')
> +	fi
> +done < /etc/fstab
> +
> +BOOT_CMD=$(mktemp)
> +
> +KERNEL_VERSION=$(linux-version list | linux-version sort --reverse | head -1)
> +
> +echo "${SCRIPT_PREPEND}" >> ${BOOT_CMD}
> +
> +echo "setenv bootargs root=${ROOT_DEV} ${KERNEL_ARGS_APPEND}" >> ${BOOT_CMD}
> +
> +echo "load \${devtype} \${devnum}:${ROOT_PART} \${fdt_addr_r}" \
> +     "/usr/lib/linux-image-${KERNEL_VERSION}/\${fdtfile}" >> ${BOOT_CMD}
> +echo "load \${devtype} \${devnum}:\${distro_bootpart} \${kernel_addr_r}" \
> +     "/boot/vmlinuz-${KERNEL_VERSION}" >> ${BOOT_CMD}
> +
> +case "${NO_INITRD}" in
> +yes|1)
> +	INITRD_ADDR="-"
> +	;;
> +*)
> +	RAMDISK_SIZE=$(printf %x \
> +		$(stat -c %s /boot/initrd.img-${KERNEL_VERSION}))
> +	echo "load \${devtype} \${devnum}:\${distro_bootpart}" \
> +	     "\${ramdisk_addr_r} /boot/initrd.img-${KERNEL_VERSION}" \
> +	     >> ${BOOT_CMD}
> +	INITRD_ADDR="\${ramdisk_addr_r}:${RAMDISK_SIZE}"

Ah, this can be done even simpler: There is ${filesize} in u-boot which
is updated automatically by the last load. Will send an update.

Jan

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