Re: [Qemu-ppc] Problem booting qemu-system-ppc with cpu e500XX and machine mpc8544ds

[Alexander Graf]

On 03.07.2012, at 20:49, Scott Wood wrote:

> On 07/03/2012 12:22 AM, Badrinath Sriman wrote:
>> I am using the bootable CDROM option only because qemu requires the
>> CDROM/hard disk images to be bootable. On real hardware, we use the
>> bootm option of U-boot. Using qemu, I was not able to find helpful
>> instructions to boot netbsd/ppc via. uboot (as bootloader).
> 
> U-Boot doesn't run in QEMU -- it would require a lot more hardware to be
> emulated and/or changes to U-Boot.
> 
>> The
>> nearest that I could come to booting netbsd/ppc combination was
>> through ofwboot as the bootloader.
> 
> That's not going to work without an Open Firmware implementation, which
> we don't have on e500 either in QEMU or on real hardware. :-)
> 
>> I am now trying to use the -kernel
>> option to boot the netbsd kernel. Looks like the -M mpc8544ds option
>> mandatorily requires a FDT. The netbsd that we are using does not
>> have the FDT option when it is compiled. So trying to understand more
>> about FDT and the qemu implementation of FDT, to debug the booting
>> issue.
> 
> QEMU will pass an FDT to the target, but the target doesn't need to use
> it.  The FDT comes from QEMU -- it used to be in pc-bios/, but on

Yes. You do need libfdt however installed on the host, because we will pass an 
fdt into the guest regardless.

> top-of-tree it is now generated internally to QEMU and doesn't need to
> be passed in on the command line anymore.
> 
> However, a problem with the target OS not being device tree driven is
> that QEMU doesn't emulate all the hardware on a real mpc8544ds.  It
> emulates a small subset, and the device tree is how this subset is
> communicated.  So you'll have to somehow make sure that NetBSD is not
> trying to access any devices other than the one serial port, the one PCI
> bus, and the reset register in the global utilities block.

Or you implement all the hardware a real mpc8544ds would have in QEMU and send 
patches :). I'd love to see NetBSD work properly on that target.


Alex