port-arm/57117: overlay path changed with armboot.efi

[mlelstv%netbsd.org@localhost]

>Number:         57117
>Category:       port-arm
>Synopsis:       overlay path changed with armboot.efi
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    port-arm-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Dec 18 12:15:00 +0000 2022
>Originator:     Michael van Elst
>Release:        NetBSD 10.99.1
>Organization:
	
>Environment:
	
	
System: NetBSD gruezm 10.99.1 NetBSD 10.99.1 (GRUEZM) #60: Sun Dec 18 11:21:37 UTC 2022 mlelstv@slowpoke:/home/netbsd-current/obj.earmv7hf/scratch/netbsd-current/src/sys/arch/evbarm/compile/GRUEZM evbarm
Architecture: earmv7hf
Machine: evbarm
>Description:
In netbsd-9 bootarm.efi would interpret a boot.cfg file on the EFI
partition.

Lines like:

dtoverlay=/overlays/spi.dtbo
dtoverlay=/overlays/i2c.dtbo

would load DTB overlays from a subdirectory on the EFI partition.

With netbsd-current, the bootloader complains that the files cannot
be found and stops without even loading the kernel.

Creating an overlays directory on the root partition with the required
files makes bootarm.efi happy again.

Changing the lines to e.g.:

dtoverlay=hd0e:/overlays/spi.dtbo
dtoverlay=hd0e:/overlays/i2c.dtbo

to make it compatible with old and new bootloader doesn't work. While
the bootloader accepts the path to the EFI partition, this also changes
the path to the root partition for the kernel (now hd0e:/).

>How-To-Repeat:
Update from netbsd-9 bootarm.efi to netbsd-current bootarm.efi.
>Fix:
Make dtoverlay always default to the EFI partition (where dtb files and
overlays reside) and let it preserve the root device.

>Unformatted: