Re: [Qemu-ppc] [Qemu-devel] [PATCH 3/3] PPC PReP: can run without bios image

[Peter Maydell]

On 4 April 2013 12:53, Andreas Färber <address@hidden> wrote:
> Alex, isn't ARM running without -bios? Instead of a firmware blob it has
> some hardcoded firmware'ish instructions in the loader code.

Varies from board to board, but yes, generally we have a trivial
bootloader (which on uniprocessor machines doesn't actually run
guest code, it just sets registers and memory up to jump to the
kernel).

> For PReP, Fabien has not stated what his use case actually is (in
> particular which hardware?), so it's hard for me to comment on what the
> hardware actually does and I thus won't accept random changes just
> because they happen to be in Leon3 code. There's nothing conceptually
> wrong with loading ELF code so I'm positive we will find a solution to
> accommodate all use cases in some way. :)

ARM also lets you pass an ELF file to -kernel which it treats
as "just pull this blob into RAM and jump to its entrypoint".
This is useful for 'bare metal' type test cases (equivalent
of dumping a file in over JTAG). The UI is all wrong, though:
-kernel should always mean "load a Linux kernel" and we should
have some other way (ideally a cross-architecture way) of saying
"just load this binary blob and start it". (-bios isn't that
because -bios tends to (a) mean different things on different
boards and (b) mean 'put this in flash or whatever' rather than
'dump stuff in RAM and go'.)

-- PMM