[Pkg-raspi-maintainers] Bug#977694: 5.10.4 Debian kernel does not boot on raspi 4 with ext4 rootfs and usb-msd

[João Ricardo Sares Teles de Matos]

I ran into this issue while trying to migrate the root filesystem into a 
btrfs subvolume on an USB hard drive.
I'm also using a Raspberry Pi 4B.

I followed Ryutaroh's advice of loading the reset_raspberrypi module, as 
follows:

 > echo reset_raspberrypi >/etc/initramfs-tools/modules
 > update-initramfs -uk all

And now I can boot from USB.


Note that this issue also causes any other USB devices to be missing 
while in initramfs, including USB keyboards, which might be useful in a 
rescue shell.

Sidenote: the rescue shell only seems to be spawned on the serial 
terminal currently, so having a USB keyboard is still useless in that 
regard, but that's another issue.


I feel inclined to agree with the idea of adding the file

 > /usr/share/initramfs-tools/modules.d/raspi-firmware.conf

with the contents

 > reset_raspberrypi

to the package raspi-firmware, provided that it doesn't interfere with 
the rest of the Raspberry Pi family.

Best regards, João Matos