Re: [Qemu-devel] [PATCH 5/7] hw/arm/boot: Allow easier swapping in of different loader code

[Peter Maydell]

On 17 December 2013 11:36, Peter Crosthwaite
<address@hidden> wrote:
> On Tue, Dec 17, 2013 at 8:31 PM, Peter Maydell <address@hidden> wrote:
>> I'm not convinced about this at all -- this would be letting the
>> "I know about booting Linux" code spread out from boot.c
>> where it currently is into every device. That sounds like a bad idea. -
>>
>
> So the "I know about boot linux" code already has to span multiple
> architectures it's already reasonably 'spread out' just looking at the
> zoo of Linux bootloaders. Its also a contributor to the much disliked
> inconsistencies in boot flow between archs.
>
> If we can outsource arch/board specific bringup to device land it
> would allow consolidation of all the different Linux bootloaders. Or
> at least across embedded - E.g. Microblaze, ARM, some of the board
> level PPC bootloaders O.R. and the newly posted Moxie machine.
>
> ARM_CPU / MICROBLAZE_CPU would be responsible for setting dtb reg ptr
> / kernel args, program entry point.
> ARM_GIC would set itself up.

...but how? What the GIC state needs to be depends on the board.

It's times like this I see the appeal of pushing the whole thing off onto
a custom "firmware blob" which does the work :-)

> we are not going to solve this today and at the end of the day, the
> patch does make this much more self documenting and flexible for ARM,
> so:
>
> Reviewed-by: Peter Crosthwaite <address@hidden>

Thanks.

-- PMM