mes/BOOTSTRAP

                                                              -*- org -*-
#+TITLE: bootstrappable.org project

Copyright © 2016,2017,2018,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>

  Copying and distribution of this file, with or without modification,
  are permitted in any medium without royalty provided the copyright
  notice and this notice are preserved.

* What?
** Full source bootstrapping for GNU Guix

A package in Guix is uniquely identified by the hash of its source code,
its dependencies, and its build recipe.

Every package can be built from source, except for the bootstrap
binaries.

*** From the Guix manual

   The distribution is fully “bootstrapped” and “self-contained”: each
package is built based solely on other packages in the distribution.

The root of this dependency graph is a small set of “bootstrap
binaries”, provided by the ‘(gnu packages bootstrap)’ module.  For more
information on bootstrapping, *note Bootstrapping::.

**** Guix bootstrap tarballs

$ du -schx $(readlink $(guix build bootstrap-tarballs)/*)
2.1M	/gnu/store/9623n4bq6iq5c8cwwdq99qb7d0xj93ym-binutils-static-stripped-tarball-2.28.1/binutils-static-stripped-2.28.1-x86_64-linux.tar.xz
18M	/gnu/store/437xwygmmwwpkddcyy1qvjcv4hak89pb-gcc-stripped-tarball-5.5.0/gcc-stripped-5.5.0-x86_64-linux.tar.xz
1.8M	/gnu/store/55ccx18a0d1x5y6a575jf1yr0ywizvdg-glibc-stripped-tarball-2.26.105-g0890d5379c/glibc-stripped-2.26.105-g0890d5379c-x86_64-linux.tar.xz
5.7M	/gnu/store/bqf0ajclbvnbm0a46819f30804y3ilx0-guile-static-stripped-tarball-2.2.3/guile-static-stripped-2.2.3-x86_64-linux.tar.xz
5.8M	/gnu/store/j8yzjmh9sy4gbdfwjrhw46zca43aah6x-static-binaries-tarball-0/static-binaries-0-x86_64-linux.tar.xz
33M	total
$ for i in $(readlink $(guix build bootstrap-tarballs)/*);\
  do sudo tar xf $i; done
$ du -schx *
130M	bin
13M	include
54M	lib
51M	libexec
5.2M	share
252M	total

* Why?
** Reproducibility is essential to Software Freedom

Reproducible builds are a set of software development practices that
create a verifiable path from human readable source code to the binary
code used by computers.

*** What about the bootstrap binaries and the compilers?

We have the sources: they always lead to bitwise-same binary, but what
about the bootstrap binaries and compilers?

*** The current way out: Ignore the problem

 ``recipe for yogurt: add yogurt to milk''

*** New solution: Full source bootstrapping path

* How?
** Software: MesCC-tools, M2-Planet, GNU Mes and MesCC
** MesCC-tools

    https://savannah.gnu.org/projects/mescc-tools

*** hex.0: ~500 byte well-documented, self-hosting hex assembler

This 500 byte program is written in ASCII hex.  When converted
byte-for-byte from ASCCI to binary we have the only binary seed that
our full source bootstrap path needs.

We bless this simple and easily verifyable binary and consider it to
be source.

*** hex1: next level hex assembler written in hex.0
*** M0: a macro assembler written in hex.1
*** M1: a macro assembler written in M0
*** hex2: a hex2 linker written in M0
*** M2-Planet: a self-hosting M2 (C-with-structs) transpiler written in M1
*** GNU Mes: A Scheme interpreter written in C, with cpp transformed into M2
*** MesCC: A C compiler written in Scheme
*** tcc-boot: a patched version of TinyCC

** GNU Mes and MesCC

    https://www.gnu.org/software/mes

*** mes.c: a Scheme interpreter in ~5,000LOC of simple C
*** mescc: a C compiler written in Scheme (uses Nyacc C99 parser in Scheme)
*** mes.M2: this Scheme interpreter in preprocessed M2

** TinyCC

    https://gitlab.com/janneke/tinycc

* TODO
** remove or upstream patches from tcc-boot
** prepare src/mes.c for M2-Planet transpiler.
** ARM, the Hurd
** fix bootstrap-loops: (Nyacc?, mes.M2, psyntax.pp?)
** make GNU gcc (8.0?) bootstrappable again, remove [need for] tcc stage
* DONE
** upstream mes-boot to Guix.
** replace Guix bootstrap for x86_64.
** replace Guix bootstrap for x86.
** add full source gcc-4.7 package build.
** bootstrap gcc+glibc-built binutils-20.1, gcc-4.1.0.
** have tcc-boot compile gnutools triplet: binutils-2.14, gcc-2.95.3, glibc-2.2.5.
** have tcc-boot's mes-tcc compile a fully functional tcc
** hex.0, hex.1, M0
** M1, hex2_linker in simple C
** M2-Planet is now self-hosting, written in M2
** mes+mescc are mutual self-hosting
** patched tcc compiled with mes+mescc
** during development we run mescc on Guile (mes is ~30 times slower)
** tcc compiled with gcc is known to compile gcc

* Contact
** #bootstrappable, #guix on freenode
** bootstrappable.org