Today we don't run any firmware on our e500 platform. You're either running
a Linux kernel directly through -kernel or you don't boot the VM at all.
This is bad for multiple reasons. The normal firmware on e500 based systems
is u-boot. Some OSes (IIRC FreeBSD) rely on u-boot for their 2nd stage boot
loader. Since that relies on interfaces u-boot provides we can't execute it
today.
The other case where we're falling short of expectations that I'm aware of
is network boot. With a firmware you can actually pxe boot a virtual machine.
This patch set implements all the pieces necessary to run u-boot as the
firmware for our e500 platforms: mpc8544ds and e500plat. It is based on upstream
u-boot code that implements a target specific for the simplified system QEMU
implements.
Due to popular demand the default -kernel booting has *not* been changed from
directly booting into the kernel. This is possible because we don't need to run
firmware to provide run time services.
However, whenever the user explicitly defines a -bios blob, we run it.
That means if you want to route a -kernel boot through u-boot you have to pass
in -bios pc-bios/u-boot.e500 -kernel uImage.
Please try out as many things as you're able to try.
Known missing bits:
- -boot doesn't get interpreted yet
- pflash is missing, so the environment is volatile
- no block drivers available (ata_piix is broken in u-boot and virtio-blk
is missing)
- KVM patches to support u-boot are probably going to hit 3.16