J. Mayer wrote:
> On Wed, 2007-04-11 at 17:49 -0400, Rob Landley wrote: 
>   
>> qemu-system-ppc -M prep -nographic -kernel zImage-powerpc -append \
>>   "console=/dev/ttyS0"
>>     
>
> You cannot append anything to the command line this way, with the PPC
> firmware...
> You can append options when using yaboot, not with the -kernel option.
> Then, you should use the CONFIG_CMDLINE kernel option to add the option
> you absolutely need to boot.
>   
If you do not modify the prep loader, then it is impossible to pass 
arguments or load a kernel that expands to > 4meg.  With respect to  
using an unmodified prep loader, you have to build the boot arguments 
you want into the kernel itself with the .config file options.
> [...] 
>   
>>> It also seems that most Linux 2.6 kernels support has been broken. It
>>> used to run too, with some versions having a great problem in
>>> frame-buffer mode (writing black on black is not really usable). Using
>>> the serial console always allowed me to follow the boot until X starts.
>>>       
>> I'm trying to use serial console.
>>     
>
> I tried and the kernel seem to hang before reaching the start_kernel
> routine. That why I said there may now be a CPU emulation bug that broke
> everything.... Must do more checks with a debug kernel (with traces,
> this time. Using early_printk may help a lot !).
>
> [...]
>
>   
> you may try to boot kernels in PREP format as they look like regular boot partitions...
> It may help.
>
>   

While I am sure folks have the objective to be able to boot something 
that is not modified, my objective was to modify the kernel to work with 
qemu until that first objective is met.  If you use a 2.6.21rc candidate 
you can use the attached patches to boot.  I provided a .config file as 
well.  The frame buffer is definitely broken, but I had not really 
looked into why because I was more interested in simply using the ppc 
instruction sets.

Note I startup with the following and it works perfectly fine with my 
modified kernels:
qemu-system-ppc -nographic -kernel zImage.prep -s -M prep -append 
"console=ttyS0 ip=dhcp root=/dev/nfs nfsroot=10.0.2.2:/export/ppc rw 
netdev=9,0x300,eth0"

There is a new regression between Apr 9 and Apr 10 in the QEMU CVS HEAD 
where tcp checksums are failing again.  :-(

If it would help, I can certainly provide some of my zImage files which 
run with several different 2.6.x kernels.

Jason.