Cannot install /boot/efi on boot media

[Heinrich Schuchardt]

When installing on RISC-V using an SD-card image it would be preferable to reuse the EFI system partition of the installation medium as mount point /boot/efi.

When I choose "custom layout" the ESP of the installation medium cannot be chosen as mount point.

This is how I am testing on QEMU:

dd if=/dev/zero bs=1M of=disk count=1 seek=16383
/usr/bin/qemu-system-riscv64 -machine virt -m 4G -smp cpus=8 -nographic \
        -bios /usr/lib/riscv64-linux-gnu/opensbi/generic/fw_jump.bin \
        -kernel /usr/lib/u-boot/qemu-riscv64_smode/u-boot.bin \
        -device virtio-net-device,netdev=net0 \
        -netdev user,id=net0,tftp=tftp \
        -drive if=none,file=installer.img,format=raw,id=mydisk \
        -device ich9-ahci,id=ahci \
        -device ide-hd,drive=mydisk,bus=ahci.0 \
        -drive if=none,file=disk,format=raw,id=disk \
        -device ide-hd,drive=disk,bus=ahci.1 \
        -device virtio-rng-pci

[Michael Hudson-Doyle (mwhudson)]

I guess subiquity's expectation is still that the installation media is read-only. I wonder how we can detect that this is OK to allow...