[Pkg-raspi-maintainers] Bug#865069: Bug#865069: uncompress kernel images

[Martin Schitter]

On 2017-10-07 09:16, Michael Stapelberg wrote:
>> i finally didn't use extract-vmlinux from the kernel scripts, because it
>> doesn't work for arm kernels (see:
>> https://patchwork.kernel.org/patch/8120831/), but the 7zip solution also
>> doesn't without flaws.
> 
> Can you clarify what that means? What are the flaws? Is this ready to
> merge or not?

the actual kernel source decompression script has some nasty compression 
format detection/handling flows concerning the ARM/ARM64 architecture. 
it's a well known problem since a long time, but never got fixed AFAIK.

and in case of our raspi3 boards it's a really essential problem, 
because the usual debian kernel compilation tools by default generate 
compressed images and the raspi3 firmware will not boot from them!

> Could you lower the Depends on 7zip-full to a Recommends in the
> interest of reducing the size of the Raspberry Pi images please? The
> code would need to be changed in such a way that it works both with
> 7zip present and not present.

well -- in fact we could reduce the requirements to a few lines in the 
README file, explaining, how to compile a uncompressed customized kernel 
image for raspi3s on debian systems.

but if we want to support a more user friendly and tolerant way to 
bypass this kind of issues in a fully automatic manner and prevent 
critical faults as much as possible, 7zip-full is a quite simple and 
efficient solution resp. a very well maintained and versatile package, 
because we would otherwise need a lot more precautions to handle all the 
possible different kernel image compression variants in a proper way.

but if you see a better solution, please simply ignore my suggestion.
it was just my personal answer to the fact, that it took me quite while 
to find out, why my rasp3s didn't boot with self compiled debian kernels...

martin