Re: CLI: Using -bios AND -kernel

[BALATON Zoltan]

On Wed, 20 Oct 2021, Thomas Huth wrote:
> On 20/10/2021 12.12, Philippe Mathieu-Daudé wrote:
> > Hi John / Paolo / Markus,
> >
> > On 10/19/21 12:07, BALATON Zoltan wrote:
> > > On Tue, 19 Oct 2021, Christophe Leroy wrote:
> > > > Le 19/10/2021 à 11:39, Thomas Huth a écrit :
> > > > > On 19/10/2021 11.31, Christophe Leroy wrote:
> > [...]
> > > > I use the following command, but it does nothing, it stays in uboot
> > > > prompt as when I don't get a kernel argument
> > > >
> > > >      ~/qemu/build/qemu-system-ppc -M taihu -bios
> > > > ~/Téléchargements/u-boot.bin -serial null -serial mon:stdio -kernel
> > > > arch/powerpc/boot/uImage
> > >
> > > I'm not sure using -bios and -kernel together makes sense, it probably
> > > starts u-boot in this case and you have to load and start the kernel
> > > from u-boot as you'd notmally do on a real machine. Alternatively you
> > > could use -kernel instead of -bios which then loads a kernel and starts
> > > it directly but not sure if it needs a firmware to work.
> > >
> > > Ot I could be completely wrong as I don't know this machine and haven't
> > > tried it.
> >
> > Usually -bios overwrites -kernel/-append cmdline options.
> > Having them accepted together is probably a configuration mistake,
> > and we should reject that (generically).
>
> No, having -bios and -kernel together is perfectly fine if the BIOS knows 
> about it. Have a look at the ppc64 pseries machine, it works perfectly fine 
> with -bios and -kernel at the same time.

Also this way the board can decide what's right, In pegasos2 I added a 
warning for cases that may not work as expected to let users know but on 
other machines a firmware may be needed and -kernel could set firmware 
environment to boot that loaded kernel (this may be what ref405 is trying 
to do or e500 also messes with some boot_info struct that it writes to 
guest I think). So maybe there's no generic way to handle it. These 
options are just defined by the board which is not great for UI 
consistency but may be needed for enough flexibility to implement 
everything boards want.

Regards,
BALATON Zoltan