Can't upgrade kernel on raspberry pi3a+

Tried apt install -f, and do some check.
Updated kernel looks installed, but the system still boot from original kernel.

I tried to reproduce the issue and found it is an "unsupport platform" for the tool flash-kernel

ubuntu@ubuntu:~$ dpkg -l *1044*
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-===================================================-==============================-==============================-============================================================================================================
ii linux-headers-4.15.0-1044-raspi2 4.15.0-1044.47 armhf Linux kernel headers for version 4.15.0 on ARM (hard float) SMP
ii linux-image-4.15.0-1044-raspi2 4.15.0-1044.47 armhf Linux kernel image for version 4.15.0 on ARM (hard float) SMP
ii linux-modules-4.15.0-1044-raspi2 4.15.0-1044.47 armhf Linux kernel extra modules for version 4.15.0 on ARM (hard float) SMP
ii linux-raspi2-headers-4.15.0-1044 4.15.0-1044.47 armhf Header files related to Linux kernel version 4.15.0
ubuntu@ubuntu:~$ sudo apt-get install --reinstall linux-headers-4.15.0-1044-raspi2 linux-image-4.15.0-1044-raspi2 linux-modules-4.15.0-1044-raspi2 linux-raspi2-headers-4.15.0-1044
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 4 reinstalled, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
Need to get 0 B/44.6 MB of archives.
After this operation, 0 B of additional disk space will be used.
(Reading database ... 113356 files and directories currently installed.)
Preparing to unpack .../linux-image-4.15.0-1044-raspi2_4.15.0-1044.47_armhf.deb ...
Unpacking linux-image-4.15.0-1044-raspi2 (4.15.0-1044.47) over (4.15.0-1044.47) ...
Preparing to unpack .../linux-headers-4.15.0-1044-raspi2_4.15.0-1044.47_armhf.deb ...
Unpacking linux-headers-4.15.0-1044-raspi2 (4.15.0-1044.47) over (4.15.0-1044.47) ...
Preparing to unpack .../linux-modules-4.15.0-1044-raspi2_4.15.0-1044.47_armhf.deb ...
Unpacking linux-modules-4.15.0-1044-raspi2 (4.15.0-1044.47) over (4.15.0-1044.47) ...
Preparing to unpack .../linux-raspi2-headers-4.15.0-1044_4.15.0-1044.47_armhf.deb ...
Unpacking linux-raspi2-headers-4.15.0-1044 (4.15.0-1044.47) over (4.15.0-1044.47) ...
Setting up linux-raspi2-headers-4.15.0-1044 (4.15.0-1044.47) ...
Setting up linux-modules-4.15.0-1044-raspi2 (4.15.0-1044.47) ...
Setting up flash-kernel (3.90ubuntu3.18.04.2) ...
Setting up linux-headers-4.15.0-1044-raspi2 (4.15.0-1044.47) ...
Setting up linux-image-4.15.0-1044-raspi2 (4.15.0-1044.47) ...
Processing triggers for linux-image-4.15.0-1044-raspi2 (4.15.0-1044.47) ...
/etc/kernel/postinst.d/initramfs-tools:
update-initramfs: Generating /boot/initrd.img-4.15.0-1044-raspi2
flash-kernel: deferring update (trigger activated)
/etc/kernel/postinst.d/zz...

Confirmed the 3A+ entry is missing from flash-kernel; I'll get this added for Eoan and open an SRU for Bionic (we need to backport flash-kernel to bionic anyway for Pi4 support).

Test package for devel available from PPA (we'll see about SRUing to bionic and presumably eoan once this has landed):

    https://launchpad.net/~waveform/+archive/ubuntu/flash-kernel

Relevant branch:

    https://code.launchpad.net/~waveform/ubuntu/+source/flash-kernel/+git/flash-kernel/+ref/pi3a-plus

This bug was fixed in the package flash-kernel - 3.98ubuntu6

---------------
flash-kernel (3.98ubuntu6) focal; urgency=medium

  * Remove redundant DTB-Kernel-Version field
  * Remove redundant copying of boot dtb
  * Fix mkimage_kernel tests
  * Add "pi" value for the "Method" field which copies all dtbs and overlays
    to the boot partition and provides defaults for the boot paths of the
    kernel, initrd, and u-boot script. This fixes upgrades to support the Pi 4
    on Bionic (LP: #1850678)
  * Update pi bootscript to support all flash-kernel vars, including
    calculated devtype and partition for future USB boot support
  * Add entry for Raspberry Pi 3A+ (LP: #1841955)

 -- Dave Jones <email address hidden> Thu, 07 Nov 2019 14:02:26 +0000

The test case calls out using an 18.04 image. Will the same test work with the 19.10 image? Either way please update the test case so this also applies to 19.10.

Hello Gavin, or anyone else affected,

Accepted flash-kernel into eoan-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/flash-kernel/3.98ubuntu5.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-eoan to verification-done-eoan. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-eoan. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

Tested on 3A+ under armhf and arm64; all working.

This bug was fixed in the package flash-kernel - 3.98ubuntu5.1

---------------
flash-kernel (3.98ubuntu5.1) eoan; urgency=medium

  * Backport changes from 3.98ubuntu6 to eoan
  * Remove redundant DTB-Kernel-Version field
  * Remove redundant copying of boot dtb
  * Fix mkimage_kernel tests
  * Add "pi" value for the "Method" field which copies all dtbs and overlays
    to the boot partition and provides defaults for the boot paths of the
    kernel, initrd, and u-boot script. This fixes upgrades to support the Pi 4
    on Bionic (LP: #1850678)
  * Update pi bootscript to support all flash-kernel vars, including
    calculated devtype and partition for future USB boot support
  * Add entry for Raspberry Pi 3A+ (LP: #1841955)

 -- Dave Jones <email address hidden> Thu, 07 Nov 2019 14:02:26 +0000

The verification of the Stable Release Update for flash-kernel has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

This bug was fixed in the package flash-kernel - 3.98ubuntu11~18.04.1

---------------
flash-kernel (3.98ubuntu11~18.04.1) bionic; urgency=medium

  * Permit flash-kernel to workaround an inconsistent /boot directory when
    triggered prior to the kernel finishing its triggers (LP: #1861292)

flash-kernel (3.98ubuntu10~18.04.1) bionic; urgency=medium

  * SRU of 3.98ubuntu10 to support Raspberry Pi 4B. (LP: #1847587)
  * Removed new entries from db/all.db for machines that were not already
    supported on Bionic
  * Remove "quiet splash" from kernel command line options; Bionic shipped
    without these options and we shouldn't change the boot experience for
    existing users
  * Ensure the "overlays" dir always exists on the boot partition; the Bionic
    image for the Pi 2 shipped without this dir

 -- Dave Jones <email address hidden> Wed, 29 Jan 2020 16:15:05 +0000