4.10. Emulated targets¶
Some targets barebox runs on are virtualized by emulators like QEMU, which allows basic testing of barebox functionality without the actual hardware.
4.10.1. Generic DT image¶
Supported for ARM and RISC-V. It generates a barebox image that can
be booted with the Linux kernel booting convention, which makes
it suitable to be passed as argument to the QEMU
(as well as booted just like Linux from barebox or other bootloaders).
The device tree can be passed externally via QEMU’s
-dtb option, but
also the QEMU internal device tree can be used.
The latter can be very useful with VirtIO Support, because QEMU will fix up the virtio mmio regions into the device tree and barebox will discover the devices automatically, analogously to what it does with VirtIO over PCI.
emulate.pl script shipped with barebox can be used to easily
start VMs. It reads a number of YAML files in
describe some virtualized targets that barebox is known to run on.
Controlled by command line options, these targets are built with
tuxmake if available and loaded into the emulator for either interactive
use or for automated testing with Labgrid
Install dependencies for interactive use:
cpan YAML::XS # or use e.g. libyaml-libyaml-perl on Debian
pip3 install tuxmake # optional
# Switch to barebox source directory
# emulate x86 VM runnig the EFI payload from efi_defconfig
ARCH=x86 ./test/emulate.pl efi_defconfig
# build all MIPS targets known to emulate.pl and exit
ARCH=mips ./test/emulate.pl --no-emulate
The script can also be used with a precompiled barebox tree:
# Switch to build directory
# run a barebox image built outside tuxmake on an ARM virt machine
ARCH=arm ./test/emulate.pl virt@multi_v7_defconfig --no-tuxmake
# run tests instead of starting emulator interactively
ARCH=arm ./test/emulate.pl virt@multi_v7_defconfig --no-tuxmake --test
emulate.pl also has some knowledge on paravirtualized devices:
# Run target and pass a block device (here /dev/virtioblk0)
ARCH=riscv ./test/emulate.pl --blk=rootfs.ext4 rv64i_defconfig
Needed command line options can be passed directly to the
pytest as well by placing them behind
# appends -device ? to the command line. Add -n to see the final result
ARCH=riscv ./test/emulate.pl rv64i_defconfig -- -device ?
For a complete listing of options run