Sender: =?UTF-8?Q?Timo_Ter=C3=A4s?= <timo.teras@gmail.com>
Date: Fri, 6 Mar 2015 09:49:06 +0200
From: Timo Teras <timo.teras@iki.fi>
To: Fabien Germain <fabien.germain@gmail.com>
Cc: alpine-devel <alpine-devel@lists.alpinelinux.org>
Subject: Re: [alpine-devel] Raspberry Pi 2 model B
Message-ID: <20150306094906.0ad57b74@vostro>
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On Fri, 6 Mar 2015 01:17:40 +0100
Fabien Germain <fabien.germain@gmail.com> wrote:

> On Thu, Mar 5, 2015 at 7:07 AM, Timo Teras <timo.teras@iki.fi> wrote:
> 
> > > Whereas Alpine Linux works great on Raspberry Pi B+, it does not
> > > seem to boot (black screen) with the new Raspberry Pi 2 :-( The
> > > main difference with old model is the CPU : single 700MHz ARM11
> > > --> 900MHz quad-core ARM Cortex-A7 (more details :
> > > http://www.raspberrypi.org/raspberry-pi-2-on-sale/ ).
> >
> > It's completely different CPU, with different peripherals. So it'll
> > require kernel support. We will need to pull in the kernel support
> > adjust kernel config, and see if any changes to boot sequence are
> > needed. Likely it's just matter of fixing kernel.
> >
> 
> Yes, indeed : Replacing bootcode.bin, fixup.dat and start.elf with
> latest versions from
> https://github.com/raspberrypi/firmware/tree/master/boot didn't help
> booting :-(

Those will not help much, they are pretty much the 2nd stage
bootloader and firmware for the GPU, which should be identical on rpi2.

> Only CPU was changed (and 512 more Mb of RAM), as far as I know all
> the hardware is the same.

Yeah. CPU changed, and that's the tricky bit. It requires different
kernel.

I would also like to be able to ship single image for all RPI models.
It turns out that even B and B+ have few minor differences.

I was digging and probably the easiest way is to to start using u-boot
with RPI too. We'd still need custom kernel to get all the drivers and
stuff. But we'd just compile it also in dtb mode, and ship it with dtbs
for all three RPI models, as well as u-boot for each model. u-boot
would then load the kernel with corresponding dtb. This would be a nice
step also as when full rpi support lands upstream kernels, we could use
same system image for all arm boards.

I think rpi2 support is coming in the next u-boot release. So when that
is out, this might be doable.

Meanwhile, I should probably get rpi2 unit.

/Timo


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