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Re: Testing versatile kernel on Raspberry Pi?



Thanks for your response :-)

On Monday 25 January 2016 13:23:20 Ian Campbell wrote:
> > I have a Raspberry Pi 1B, 1B+ and 2B and I'd love to test Debian's 4.4
> > kernel  for it. At least it is/was my understanding that the versatile
> > kernel is meant for the Raspberry Pi.
> 
> The versatile kernel is meant for ARM "veratile" development boards, and it
> also happens to be a reasonable platform emulated by QEMU.
> 
> It's not "versatile" in the sense of "adaptable".

I know. A slightly adapted version of the versatile kernel is used to do Pi 
simulation in QEMU and I've (also) created a repo for it: 
https://github.com/diederikdehaas/raspbian-kernel (default branch is 
kernel-3.18.x-qemu).

If you look at the changelog on linux (4.4~rc8-1~exp1) [1] you see the 
Raspberry Pi 2 explicitly mentioned and also references to BCM2836 (=Pi 2), 
BCM2835 (=Pi 1) and vc4 which stands for VideoCore4 which is the graphics chip 
for both the Pi 1 and 2.
Further reports on /. and phoronix [2] suggested that (full?) support for the 
Pi 1 and 2 was added to the upstream kernel and the changelog hinted at that 
as well. (A more recent report on /. [3] indicates that kernel 4.5 is more 
likely and it could be that it is primarily for the Pi 2.)

> I wasn't aware that any of the RPi support (for any model) had gone
> upstream.

It has taken a while, but it seems that major parts are now upstream-ed. 
See the changelog mentioned earlier.

> In any case for the RPi variants which use the older (non-armhf) processor
> you are most likely better off with the Raspbian derived distro than Debian
> armel.

That is correct, but I'm solely talking about the kernel here.

While most of the Raspbian packages work excellent, the kernel has always been 
somewhat of an issue. The Raspberry Pi Foundation (RPF) has their own linux 
kernel repo [4] (forked from upstream) and that has of course the best support 
for the RPi boards. But it is not 'properly packaged' (Debian style) and 
therefor doesn't have a linux-headers-* package [5] and all the other goodies 
I'm accustomed to with Debian kernels.

Plugwash has created Debian style kernels for the RPi, but that has its own 
drawbacks as it can safely be considered a hack and several things aren't 
working properly. And it's also quite a lot of work, which is a problem as 
he's the sole ftp-master/maintainer of the Raspbian repository. This is 
probably the reason that that kernel is still at 3.18, while the distributed 
kernel by the RPF has been on 4.1 for a while now.

As I got the impression that support for the RPi was now present in upstream 
and (therefor) the Debian kernels, I wanted to offer my help in testing it, if 
needed.
And being familiar with both Debian and the RPi and being the lead  
developer/maintainer of the Raspbian NetInstaller [6], I think I'm in a good 
position to do that.

Cheers,
  Diederik

[1] http://metadata.ftp-master.debian.org/changelogs/main/l/linux/linux_4.4-1~exp1_changelog
[2] https://www.phoronix.com/scan.php?page=article&item=linux-44-features
[3] http://linux.slashdot.org/story/16/01/24/1329206/linux-45-adds-raspberry-pi-2-support-amd-gpu-re-clocking-intel-kaby-lake
[4] https://github.com/raspberrypi/linux
[5] https://github.com/RPi-Distro/repo/issues/11
[6] https://github.com/debian-pi/raspbian-ua-netinst

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