[bug#48314] Patches to install guix system on Raspberry Pi

[Stefan]

Hi!

> @Stefan: On the other hand, I'm not sure of the general utility of 
> make-defconfig.

There is currently no simple way change the Linux configuration. Also by 
modifying the final .config as of today (which kind of contains all 
CONFIG_…-variables), as far as I know dependencies will not be resolved and 
conflicting configurations can easily happen.

A defconfig however gets striped down to a minimum of required 
CONFIG_…-variables and all “missing” ones get either default values or get 
determined through dependecies. So adding /removing/changing some few 
configurations to a defconfig is less error-prone. Further defconfig files are 
easier to maintain in git. There is a reason that only defconfig files are 
maintained in the Linux sources.

Please note that the patch allows to select a defconfig file from the Linux 
sources (if the parameter is a string), and also to provide an own defconfig 
file (if it is a file-like object).

> Sounds like a too weird special case to have general utility.

Well, there is the need already in Guix to have e.g. the predefined 
linux-libre-arm64-generic kernel, wich just uses a certain defconfig file from 
the Linux sources. But this possibility is not exported.

There are many defconfig files for all sorts of boards, especially for arm32. 
Why shouldn’t we allow to use any of these? Why should users be restrict to 
“selected” configurations? Why should Guix’ kernel configuration be preferred 
over the plain x86_64_defconfig?

And take a look at the last patch: In order to make that kernel boot on a 
Raspberry from an NFS root, some few configurations are missing, which can 
easily be added with the “modify-linux” function. By the way, maybe 
“customize-linux” would be a better name.

And there is another patch from me to make the NFS root test pass. As the Linux 
kernel build by Guix is not able to boot over NFS root in qemu, I used the same 
function there to add the missing configurations.

Oh, and finally, I need the same underlying kconfig.scm and a similar defconfig 
modification for U-Boot as well, which allowed me to simplify the existing 
U-Boot packages.


Bye

Stefan