qemu q35 mainboard¶
Running coreboot in qemu¶
Emulators like qemu don’t need a firmware to do hardware init. The hardware starts in the configured state already.
The coreboot port allows to test non mainboard specific code. As you can easily attach a debugger, it’s a good target for experimental code.
coreboot x86_64 support¶
coreboot historically runs in 32-bit protected mode, even though the processor supports x86_64 instructions (long mode).
The qemu-q35 mainboard has been ported to x86_64 and will serve as reference platform to enable additional platforms.
To enable the support set the Kconfig option
On debian you can install qemu by running:
$ sudo apt-get install qemu
On redhat you can install qemu by running:
$ sudo dnf install qemu
To run the i386 version of coreboot (default)¶
Running on qemu-system-i386 will require a 32 bit operating system.
qemu-system-i386 -bios build/coreboot.rom -serial stdio -M q35
To run the experimental x86_64 version of coreboot¶
qemu-system-x86_64 allows to run a 32 bit or 64 bit operating system
qemu-system-x86_64 -bios build/coreboot.rom -serial stdio -M q35
To test coreboot’s x86 code it’s recommended to run on a x86 host and enable KVM. It will not only run faster, but is closer to real hardware. If you see the following message:
KVM internal error. Suberror: 1 emulation failure
something went wrong. The same bug will likely cause a FAULT on real hardware, too.
To enable KVM run:
qemu-system-x86_64 -bios build/coreboot.rom -serial stdio -M q35 -accel kvm -cpu host