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

[Andreas Färber]

Am 04.04.2013 11:57, schrieb Artyom Tarasenko:
> On Thu, Apr 4, 2013 at 11:50 AM, Alexander Graf <address@hidden> wrote:
>>
>> On 04.04.2013, at 11:46, Artyom Tarasenko wrote:
>>
>>> On Thu, Apr 4, 2013 at 10:37 AM, Fabien Chouteau <address@hidden> wrote:
>>>>
>>>> On 04/03/2013 06:59 PM, Alexander Graf wrote:
>>>>>
>>>>> On 03.04.2013, at 18:40, Fabien Chouteau wrote:
>>>>>
>>>>>> If we use an ELF kernel there's no need for bios. '-bios -' means no
>>>>>> bios.
>>>>>
>>>>> This sounds like you're actually looking for a way to load an ELF blob
>>>>> as bios using -bios, not a kernel, no?
>>>>>
>>>>
>>>> No, we load the kernel with -kernel, that's what the first patch does.
>>>> But the board is implemented in such way that you can't start without a
>>>> bios. If the -bios switch is not present, then the board uses the
>>>> default bios. This patch allows to start without a bios:
>>>>
>>>> -kernel <PROGRAM> -bios -
>>>
>>> Regardless of the firmware vs. kernel discussion, I think the syntax
>>> may be improved. Under *nix '-' is commonly used for stdin. Would it
>>> be possible to specify /dev/null (under *NIX) or NUL (in the
>>> MS-World)? I think it would make the syntax more explicit.
>>
>> I'd be inclined to say that running -kernel without -bios is simply bogus 
>> and shouldn't ever happen.
> 
> QEMU does it at least in one other architectures though: leon3_generic.

Let's rather say: Fabien did it in leon3, too. ;)

Alex, isn't ARM running without -bios? Instead of a firmware blob it has
some hardcoded firmware'ish instructions in the loader code.

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. :)

Regards,
Andreas

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