Comment 8 for bug 1842284

Tested on x86 xenial-hwe. `update-initramfs` works and no ehci-platform in initrd. System works fine after reboot.

ubuntu@zwicky:~$ sudo update-initramfs -k all -u
update-initramfs: Generating /boot/initrd.img-4.15.0-65-generic
W: mdadm: /etc/mdadm/mdadm.conf defines no arrays.
update-initramfs: Generating /boot/initrd.img-4.15.0-64-generic
W: mdadm: /etc/mdadm/mdadm.conf defines no arrays.
ubuntu@zwicky:~$ ls -al /boot
total 131680
drwxr-xr-x 4 root root 4096 Sep 26 04:20 .
drwxr-xr-x 23 root root 4096 Sep 26 04:15 ..
-rw-r--r-- 1 root root 217381 Sep 13 11:11 config-4.15.0-64-generic
-rw-r--r-- 1 root root 217370 Sep 18 11:06 config-4.15.0-65-generic
drwxr-xr-x 3 root root 4096 Jan 1 1970 efi
drwxr-xr-x 5 root root 4096 Sep 26 04:16 grub
-rw-r--r-- 1 root root 54946864 Sep 26 04:20 initrd.img-4.15.0-64-generic
-rw-r--r-- 1 root root 54945126 Sep 26 04:19 initrd.img-4.15.0-65-generic
-rw------- 1 root root 4061501 Sep 13 11:11 System.map-4.15.0-64-generic
-rw------- 1 root root 4062077 Sep 18 11:06 System.map-4.15.0-65-generic
-rw------- 1 root root 8172440 Sep 17 19:28 vmlinuz-4.15.0-64-generic
-rw------- 1 root root 8181016 Sep 19 08:08 vmlinuz-4.15.0-65-generic
ubuntu@zwicky:~$ sudo dpkg -l | grep initramfs-tools-core
ii initramfs-tools-core 0.122ubuntu8.15 all generic modular initramfs generator (core tools)
ubuntu@zwicky:~/temp$ dd if=/boot/initrd.img-4.15.0-65-generic of=initrd.img bs=512 skip=4768; zcat initrd.img | cpio -i
102546+1 records in
102546+1 records out
52503910 bytes (53 MB, 50 MiB) copied, 0.17038 s, 308 MB/s
296093 blocks
ubuntu@zwicky:~/temp$ ls
bin conf etc init initrd.img lib lib64 run sbin scripts usr var
ubuntu@zwicky:~/temp$ find . -name '*hci*'
./lib/modules/4.15.0-65-generic/kernel/drivers/mmc/host/sdhci-pci.ko
./lib/modules/4.15.0-65-generic/kernel/drivers/mmc/host/sdhci.ko
./lib/modules/4.15.0-65-generic/kernel/drivers/mmc/host/sdhci-xenon-driver.ko
./lib/modules/4.15.0-65-generic/kernel/drivers/mmc/host/sdhci-acpi.ko
./lib/modules/4.15.0-65-generic/kernel/drivers/mmc/host/sdhci-pltfm.ko
./lib/modules/4.15.0-65-generic/kernel/drivers/usb/host/xhci-plat-hcd.ko
./lib/modules/4.15.0-65-generic/kernel/drivers/ata/acard-ahci.ko
./lib/modules/4.15.0-65-generic/kernel/drivers/ata/ahci_platform.ko
./lib/modules/4.15.0-65-generic/kernel/drivers/ata/ahci.ko
./lib/modules/4.15.0-65-generic/kernel/drivers/ata/libahci_platform.ko
./lib/modules/4.15.0-65-generic/kernel/drivers/ata/libahci.ko
./lib/modules/4.15.0-65-generic/kernel/drivers/firewire/firewire-ohci.ko
ubuntu@zwicky:~/temp$ uname -a
Linux zwicky 4.15.0-65-generic #74~16.04.1-Ubuntu SMP Wed Sep 18 09:51:44 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux