Recoding the configuration for live-build images

[Marcus Hoffmann]

On September 4, 2021 11:04:02 AM GMT+02:00, Richard Purdie <richard.purdie at linuxfoundation.org> wrote:
>On Sat, 2021-09-04 at 09:18 +0200, Jan Nieuwenhuizen wrote:
>> John Gilmore writes:
>> 
>> Hi!
>> 
>> > Does the GNU Mes bootstrap-reducing team have a plan to replace Grub and
>> > the Linux kernel and init (and perhaps a BIOS?) with something tiny that
>> > runs on bare metal and implements a file system, the mount command, and
>> > processes?  Many realtime OS's are much smaller than Linux or BSD and
>> > yet have those capabilities.  eCos might be a great start, and is free,
>> > highly portable, and includes a POSIX layer (and TCP/IP for debugging),
>> > though it currently lacks fork/exec/wait.  The original V7 UNIX kernel
>> > would work, if process sizes and filename sizes are patched, and a few
>> > device drivers written for modern disk and CDROM drives.  Such a
>> > bootstrap kernel would enable the Scheme bootstrap programs to run well
>> > enough to build gcc, then use gcc to build the Linux kernel, then boot
>> > it, and continue building.
>> 
>> This is a valid concern and these are nice pointers.  In my FOSDEM21
>> talk (https://fosdem.org/2021/schedule/event/gnumes/) I mention the fact
>> that we still have work to do here.  However, there are no concrete
>> plans that I know of just yet, at least not as a basis for real world
>> bootstrap of a full GNU/Linux system.
>> 
>> GNU Mes is being deployed in the GNU Guix bootstrap and a new effort has
>> just started to port the reduced binary seed bootstrap to NixOS.  We are
>> still working to integrate the "full source bootstrap" into GNU Guix.
>> The plans after that are to replace critical usage of GNU Guile with GNU
>> Mes.  There is also work on ARM, RISC-V and the Hurd going on.  This
>> probably means, e.g., backporting RISC-V support to gcc-4.6, in short:
>> lots of work todo here.
>> 
>> The fact remains that the team is still quite small and GNU Guix and
>> even NixOS I think are niche distributions.  It would be amazing to get
>> a GNU Mes based reduced binary seed bootstrap into Debian.  That could
>> increase our exposure a lot and may free up some development time for
>> doing more wild stuff.  Alas, except for chats some of us had I do not
>> know of concrete plans here either.
>
>You may want to consider Yocto Project in that area. The strength YP has is that
>it is a cross compiled and customised Linux (and other RTOS) built reproducibly
>from source with tightly controlled host dependencies. It can "self host", i.e.
>build itself reproducibily from within its own tools too.
>
>As such, there would be a very specific target that would need to be built to
>achieve bootstrap and the system could take it from there. There are also
>probably ways to minimise the bootstrap needed, that just hasn't been too much
>of a focus for the project.
>
>Cheers,
>
>Richard
>

Hi!

I'm not deeply involved in the bootstrappable project but I believe the required bootstrap seed in guix is already a lot smaller than the yocto projects  dependencies (but maybe a few steps are also still missing here). I wonder if reproducibly rebuilding the bootstrap seed is possible/easy with guix though?

I remember us talking about the Linux and bootloader dependencies at the end of the Marrakesh retreat and (due to recent exposure) I was thinking about ways to use uboot as another stage to bootstrapping a full Linux system. 

I'm unsure how good a choice this actually is for this, but I've some experience hacking on it and (at least on arm platforms) it seems kind of a natural next lower level. On the plus side it has fairly good hardware support already, already has a rudimentary inbuilt shell and is easily extensible. There's not really any resemblance of a POSIX api though I think.

I wonder what some goalpost here would look like. Compiling some (old) version of the Linux kernel from uboot? I'll need to read up on the current bootstrap path again.

Marcus