remove linux-headers from SDK when KERNEL_NAME is blank

[hiromotai7]

Purpose

This commit adds an option to create an image without a kernel when KERNEL_NAME = "" is defined in local.conf.
This option is mainly intended for providing images for kernel testing.

• This option is now only available for Qemu.

Test

How to test

setting local.conf as below.

MACHINE = "qemu-arm64"
KERNEL_NAME = ""

build emlinux-image-base.

$ bitbake emlinux-image-base

Test result

The build was succeed.

$ bitbake emlinux-image-base
Loading cache: 100% |######################################################################| Time: 0:00:00
Loaded 1848 entries from dependency cache.
Parsing recipes: 100% |####################################################################| Time: 0:00:01
Parsing of 1260 .bb files complete (1140 cached, 120 parsed). 2208 targets, 12 skipped, 0 masked, 0 errors.
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
NOTE: Resolving any missing task queue dependencies
Sstate summary: Wanted 7 Local 0 Mirrors 0 Missed 7 Current 0 (0% match, 0% complete)      | ETA:  0:00:00
Initialising tasks: 100% |#################################################################| Time: 0:00:00
NOTE: Executing Tasks
NOTE: Tasks Summary: Attempted 52 tasks of which 7 didn't need to be rerun and all succeeded.

$

The build artifacts are as below. confirmed without a kernel image.

$ ls -l tmp/deploy/images/qemu-arm64/
total 184696
-rw-r--r-- 1 build build    123446 Jan  5 18:37 emlinux-image-base-emlinux-bookworm-qemu-arm64.dpkg_status
-rw-r--r-- 1 build build 306900992 Jan  5 18:37 emlinux-image-base-emlinux-bookworm-qemu-arm64.ext4
-rw-r--r-- 1 build build      6391 Jan  5 18:37 emlinux-image-base-emlinux-bookworm-qemu-arm64.manifest
$

[masami256]

@hiromotai7 Please check building an sdk instead of building an image because this PR changes the artifact of SDK .

Building emlinx-image-weston image and sdk for emlinux-image-weston failed to build by following error. So it looks as if emlinux-image-weston can't build with empty KERNEL_NAME variable.

build@e291cca2a2ba:~/work/build$ bitbake emlinux-image-weston -c populate_sdk
>>>> snip <<<<
NOTE: Executing Tasks
ERROR: emlinux-image-weston-1.0-r0 do_rootfs_postprocess: ExecutionError(['sudo', '-E', 'chroot', '/home/build/work/build/tmp/work/emlinux-bookworm-arm64/emlinux-image-weston-qemu-arm64/1.0-r0/rootfs', '/usr/sbi
n/useradd', '--groups', 'video,input,render,wayland', '--home-dir', '/home/weston', '--create-home', 'weston'], 6, '', "useradd: group 'input' does not exist\n")
ERROR: Logfile of failure stored in: /home/build/work/build/tmp/work/emlinux-bookworm-arm64/emlinux-image-weston-qemu-arm64/1.0-r0/temp/log.do_rootfs_postprocess.546927
Log data follows:
| DEBUG: Executing python function do_rootfs_postprocess
| DEBUG: Executing shell function rootfs_do_mounts
| DEBUG: Shell function rootfs_do_mounts finished
| DEBUG: Executing shell function rootfs_do_qemu
>>>> snip <<<<
| DEBUG: Executing shell function image_postprocess_populate_systemd_preset
| Failed to preset unit, unit /etc/systemd/system/systemd-firstboot.service is masked.
| Failed to preset unit, unit /lib/systemd/system/x11-common.service is masked.
| Failed to preset unit, unit /lib/systemd/system/hwclock.service is masked.
| Failed to preset unit, unit /lib/systemd/system/rcS.service is masked.
| Failed to preset unit, unit /lib/systemd/system/cryptdisks-early.service is masked.
| Failed to preset unit, unit /lib/systemd/system/rc.service is masked.
| Failed to preset unit, unit /lib/systemd/system/cryptdisks.service is masked.
| Unit /etc/systemd/system/systemd-firstboot.service is masked, ignoring.
| Created symlink /etc/systemd/system/sockets.target.wants/systemd-networkd.socket → /lib/systemd/system/systemd-networkd.socket.
| Created symlink /etc/systemd/system/sysinit.target.wants/systemd-network-generator.service → /lib/systemd/system/systemd-network-generator.service.
| Unit /lib/systemd/system/x11-common.service is masked, ignoring.
| Created symlink /etc/systemd/system/dbus-org.freedesktop.network1.service → /lib/systemd/system/systemd-networkd.service.
| Created symlink /etc/systemd/system/multi-user.target.wants/systemd-networkd.service → /lib/systemd/system/systemd-networkd.service.
| Created symlink /etc/systemd/system/network-online.target.wants/systemd-networkd-wait-online.service → /lib/systemd/system/systemd-networkd-wait-online.service.
| Unit /lib/systemd/system/hwclock.service is masked, ignoring.
| Created symlink /etc/systemd/system/ctrl-alt-del.target → /lib/systemd/system/reboot.target.
| Unit /lib/systemd/system/rcS.service is masked, ignoring.
| Created symlink /etc/systemd/system/sysinit.target.wants/systemd-sysext.service → /lib/systemd/system/systemd-sysext.service.
| Created symlink /etc/systemd/system/multi-user.target.wants/remote-veritysetup.target → /lib/systemd/system/remote-veritysetup.target.
| Created symlink /etc/systemd/system/multi-user.target.wants/remote-cryptsetup.target → /lib/systemd/system/remote-cryptsetup.target.
| Unit /lib/systemd/system/cryptdisks-early.service is masked, ignoring.
| Unit /lib/systemd/system/rc.service is masked, ignoring.
| Unit /lib/systemd/system/cryptdisks.service is masked, ignoring.
| DEBUG: Shell function image_postprocess_populate_systemd_preset finished
| DEBUG: Executing python function image_postprocess_accounts
| DEBUG: Python function image_postprocess_accounts finished
| DEBUG: Executing shell function rootfs_do_umounts
| DEBUG: Shell function rootfs_do_umounts finished
| DEBUG: Python function do_rootfs_postprocess finished
ERROR: Task (/home/build/work/build/../repos/meta-emlinux/recipes-core/images/emlinux-image-weston.bb:do_rootfs_postprocess) failed with exit code '1'
NOTE: Tasks Summary: Attempted 77 tasks of which 0 didn't need to be rerun and 1 failed.

Summary: 1 task failed:
  /home/build/work/build/../repos/meta-emlinux/recipes-core/images/emlinux-image-weston.bb:do_rootfs_postprocess
Summary: There was 1 ERROR message, returning a non-zero exit code.

[hiromotai7]

@masami256 This issue was caused because the input group did not exist.

ERROR: emlinux-image-weston-1.0-r0 do_rootfs_postprocess: ExecutionError(['sudo', '-E', 'chroot', '/home/build/work/build/tmp/work/emlinux-bookworm-arm64/emlinux-image-weston-qemu-arm64/1.0-r0/rootfs', '/usr/sbin/useradd', '--groups', 'video,input,render,wayland', '--home-dir', '/home/weston', '--create-home', 'weston'], 6, '', "useradd: group 'input' does not exist\n")
ERROR: Logfile of failure stored in: /home/build/work/build/tmp/work/emlinux-bookworm-arm64/emlinux-image-weston-qemu-arm64/1.0-r0/temp/log.do_rootfs_postprocess.546927

The build error did not occur after adding the following setting to local.conf.

MACHINE = "qemu-arm64"
KERNEL_NAME = ""
GROUPS += "input"

I found that normally the input group is created by udev's postinst process. At the same time, the render group is also created. I also found that udev is not installed when "KERNEL_NAME" is blank.
So in commit 62250d3, installed udev and removed the extra setting for the render group from the emlinux-image-weston.bb.

Also, I think the kernel testing will not work as expected if udev does not exist.
Therefore, in commit f6e2afe, I added udev to IMAGE_PREINSTALL in the emlinux-image-base.bb.

Please review the added commits. Thanks.