Re: Question about loading bare metal firmware

[Alistair Francis <alistair23@gmail.com>]

On Tue, Sep 13, 2022 at 4:57 PM Clément Chigot <chigot@adacore.com> wrote:
>
> > > Hi all,
> > >
> > > I'm wondering if there is an official way to load bare metal software
> > > within qemu emulations.
> > > I've seen a lot of people (including us) using -kernel. However, the
> > > doc seems to imply that the generic loader would be a better approach
> > > (cf [1]). I know that the compatibility with older Qemus is one of the
> > > reasons why -kernel is still highly used. I've also seen that the
> > > reset vector can be initialized automatically by -kernel unlike with
> > > the generic loader (this is the case with RiscV AFAICT).
> > > But is there any kind of official recommendation on that topic ?
> >
> > The recommendation is in the document you linked. For bare metal use the
> > generic loader and make sure you put the blob in the right place so the
> > architectural reset vector will jump to it.
>
> Alright. I should have missed something when I tried with the generic loader.
> Thanks for the inputs and the confirmation that we were doing something wrong !

Just another note that for a few RISC-V machines we load OpenSBI by
default. So if you don't want OpenSBI you should also specify `-bios
none`. You should also be able to just use `-bios <my_elf>` to load
your bare metal application

Alistair

>
> Thanks,
> Clément
>