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

[Alexander Graf]

On 04.04.2013, at 18:41, Peter Maydell wrote:

> On 4 April 2013 17:34, Alexander Graf <address@hidden> wrote:
>> On 04.04.2013, at 18:30, Peter Maydell wrote:
>>> * -kernel (if it means anything at all) has to mean "boot in
>>> the way a Linux kernel expects and defines its boot protocol"
>> 
>> This is what -kernel does. If more OSs than Linux end up happy with
>> that interface, great. Examples for that are multiboot kernels on
>> x86. But in general, kernels want to talk to firmware.
> 
> Agreed.
> 
>>> * "just load a binary and run it" needs to be some other option,
>>> because that's not the same thing
>> 
>> This is what -bios does. Maybe we should add an alias and call it
>> "-firmware", but the idea stays the same. That's the initial blob
>> executed when a VM gets up.
> 
> No, in general this isn't what -bios does. Usually -bios means
> "take a blob and put it wherever this board expects to have
> a ROM or flash firmware image". So on highbank it goes in the
> sysram at 0xfff88000, on shix it's 0x4000 bytes loaded at address 0,
> on mips_malta it's an image to load into a flash device, and
> so on. And on some boards it does nothing at all, because we
> ignore the parameter.

For blobs, I agree. But for ELF, we could just use the ELF information to load 
it somewhere else. It would certainly be a much more natural fit than -kernel.

> What is being asked for (and what ARM's -kernel does at the
> moment if you pass it an ELF image) is "just load the ELF
> image where the ELF image says to put it, and jump to the
> ELF image's entrypoint".

I don't see why we couldn't make this the expected behavior for -bios. You want 
to load a blob at the same layer as firmware, no?


Alex