How to build a disk image?

[Vincent DEFERT <vincent.defert%posteo.net@localhost>]

I'd like to build an image I can write to an SD card, so I did:

./build.sh -U -u -O ../obj -T ../tools -m riscv -a riscv64 release
./build.sh -U -u -O ../obj -T ../tools -m riscv -a riscv64 kernel=GENERIC64

and then:

./build.sh -U -u -O ../obj -T ../tools -m riscv -a riscv64 
disk-image=GENERIC64

but I get the following error:

> ===> build.sh command:    ./build.sh -U -u -O ../obj -T ../tools -m 
riscv -a riscv64 disk-image=GENERIC64
> ===> build.sh started:    Fri Jul  4 15:56:30 CEST 2025
> ===> NetBSD version:      10.99.14
> ===> MACHINE:             riscv
> ===> MACHINE_ARCH:        riscv64
> ===> Build platform:      Linux 6.12.35_1 x86_64
> ===> HOST_SH:             /usr/sbin/sh
> ===> share/mk MAKECONF:   /etc/mk.conf
> ===> MAKECONF file:       /etc/mk.conf (File not found)
> ===> TOOLDIR path: /home/wrk/netbsd/risc-v/src/../tools
> ===> DESTDIR path: /home/wrk/netbsd/risc-v/src/../obj/destdir.riscv
> ===> RELEASEDIR path: /home/wrk/netbsd/risc-v/src/../obj/releasedir
> ===> Updated makewrapper: 
/home/wrk/netbsd/risc-v/src/../tools/bin/nbmake-riscv
> nbmake: don't know how to make smp_GENERIC64. Stop
>
> nbmake: stopped making "smp_GENERIC64" in /home/wrk/netbsd/risc-v/src/etc
>
> ERROR: Failed to make smp_GENERIC64 in "/home/wrk/netbsd/risc-v/src/etc"
>
> *** BUILD ABORTED ***

What am I supposed to use as TARGET argument for disk-image= instead of 
GENERIC64?