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diff --git a/doc/guix.texi b/doc/guix.texi index aab8978fca..a1a37771cc 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -24285,7 +24285,80 @@ Binutils, libc, and the other packages mentioned above---the These bootstrap binaries are ``taken for granted'', though we can also re-create them if needed (more on that later). -@unnumberedsec Preparing to Use the Bootstrap Binaries +For @code{i686-linux} and @code{x86_64-linux} the Guix bootstrap process is +more elaborate, @pxref{Reduced Binary Seed Bootstrap}. + +@menu +* Reduced Binary Seed Bootstrap:: A Bootstrap worthy of GNU. +* Preparing to Use the Bootstrap Binaries:: Building that what matters most. +@end menu + +@node Reduced Binary Seed Bootstrap +@section The Reduced Binary Seed Bootstrap + +Guix---like other GNU/Linux distributions---is traditionally bootstrapped from +a set of bootstrap binaries: Bourne shell, command-line tools provided by GNU +Coreutils, Awk, Findutils, `sed', and `grep' and Guile, GCC, Binutils, and the +GNU C Library (@pxref{Bootstrapping}). Usually, these bootstrap binaries are +``taken for granted.'' + +Taking these binaries for granted means that we consider them to be a correct +and trustworthy `seed' for building the complete system. Therein lies a +problem: the current combined size of these bootstrap binaries is about 250MB +(@pxref{Bootstrappable Builds,,, mes, GNU Mes}). Auditing or even inspecting +these is next to impossible. + +For @code{i686-linux} and @code{x86_64-linux}, Guix now features a ``Reduced +Binary Seed'' bootstrap @footnote{We would like to say: ``Full Source +Bootstrap'' and while we are working towards that goal it would be hyperbole +to use that term for what we do now.}. + +The Reduced Binary Seed bootstrap removes the most critical tools---from a +trust perspective---from the bootstrap binaries: GCC, Binutils and the GNU C +Library are replaced by: @code{bootstrap-mescc-tools} (a tiny assembler and +linker) and @code{bootstrap-mes} (a small Scheme Interpreter and a C compiler +written in Scheme and the Mes C Library, built for TinyCC and for GCC). Using +these new binary seeds and a new set of +@c +packages@footnote{@c +nyacc-boot, +mes-boot, +tcc-boot0, +tcc-boot, +make-mesboot0, +diffutils-mesboot, +binutils-mesboot0, +gcc-core-mesboot, +mesboot-headers, +glibc-mesboot0, +gcc-mesboot0, +binutils-mesboot, +make-mesboot, +gcc-mesboot1, +gcc-mesboot1-wrapper, +glibc-headers-mesboot, +glibc-mesboot, +gcc-mesboot, +and +gcc-mesboot-wrapper. +} +@c +the ``missing'' Binutils, GCC, and the GNU C Library are built from source. +From here on the more traditional bootstrap process resumes. This approach +has reduced the bootstrap binaries in size to about 130MB. Work is ongoing to +reduce this further. If you are interested, join us on @code{#bootstrappable} +on the Freenode IRC network. + +@c ./pre-inst-env guix graph --type=bag -e '(begin (use-modules (guix packages)) (%current-system "i686-linux") (@@ (gnu packages commencement) gcc-mesboot))' > doc/images/gcc-mesboot-bag-graph.dot +@c dot -T png doc/images/gcc-mesboot-bag-graph.dot > doc/images/gcc-mesboot-bag-graph.png + +Below is the generated dependency graph for @code{gcc-mesboot}, the bootstrap +compiler used to build the rest of GuixSD. + +@image{images/gcc-mesboot-bag-graph,6in,,Dependency graph of the gcc-mesboot} + +@node Preparing to Use the Bootstrap Binaries +@section Preparing to Use the Bootstrap Binaries @c As of Emacs 24.3, Info-mode displays the image, but since it's a @c large image, it's hard to scroll. Oh well. @@ -24299,7 +24372,15 @@ packages bootstrap)} module. A similar figure can be generated with @example guix graph -t derivation \ -e '(@@@@ (gnu packages bootstrap) %bootstrap-gcc)' \ - | dot -Tps > t.ps + | dot -Tps > gcc.ps +@end example + +or, for the Reduced Binary Seed bootstrap + +@example +guix graph -t derivation \ + -e '(@@@@ (gnu packages bootstrap) %bootstrap-mes)' \ + | dot -Tps > mes.ps @end example At this level of detail, things are @@ -24331,10 +24412,10 @@ write them in an output directory with the right layout. This corresponds to the @code{#:modules} argument of @code{build-expression->derivation} (@pxref{Derivations}). -Finally, the various tarballs are unpacked by the -derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv}, -etc., at which point we have a working C tool chain. - +Finally, the various tarballs are unpacked by the derivations +@code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv}, or +@code{bootstrap-mes-0.drv} and @code{bootstrap-mescc-tools-0.drv}, at which +point we have a working C tool chain. @unnumberedsec Building the Build Tools @@ -24399,9 +24480,11 @@ those rarely need to be updated. Nevertheless, it is useful to have an automated way to produce them, should an update occur, and this is what the @code{(gnu packages make-bootstrap)} module provides. -The following command builds the tarballs containing the bootstrap -binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture -of Coreutils and other basic command-line tools): +The following command builds the tarballs containing the bootstrap binaries +(Binutils, GCC, glibc, for the traditional bootstrap and linux-libre-headers, +bootstrap-mescc-tools, bootstrap-mes for the Reduced Binary Seed bootstrap, +and Guile, and a tarball containing a mixture of Coreutils and other basic +command-line tools): @example guix build bootstrap-tarballs @@ -24419,12 +24502,12 @@ know. @unnumberedsec Reducing the Set of Bootstrap Binaries -Our bootstrap binaries currently include GCC, Guile, etc. That's a lot -of binary code! Why is that a problem? It's a problem because these -big chunks of binary code are practically non-auditable, which makes it -hard to establish what source code produced them. Every unauditable -binary also leaves us vulnerable to compiler backdoors as described by -Ken Thompson in the 1984 paper @emph{Reflections on Trusting Trust}. +Our traditional bootstrap includes GCC, GNU Libc, Guile, etc. That's a lot of +binary code! Why is that a problem? It's a problem because these big chunks +of binary code are practically non-auditable, which makes it hard to establish +what source code produced them. Every unauditable binary also leaves us +vulnerable to compiler backdoors as described by Ken Thompson in the 1984 +paper @emph{Reflections on Trusting Trust}. This is mitigated by the fact that our bootstrap binaries were generated from an earlier Guix revision. Nevertheless it lacks the level of @@ -24436,8 +24519,19 @@ The @uref{http://bootstrappable.org, Bootstrappable.org web site} lists on-going projects to do that. One of these is about replacing the bootstrap GCC with a sequence of assemblers, interpreters, and compilers of increasing complexity, which could be built from source starting from -a simple and auditable assembler. Your help is welcome! - +a simple and auditable assembler. + +Our first major achievement is the replacement of of GCC, the GNU C Library +and Binutils by MesCC-Tools (a simple hex linker and macro assembler) and Mes +(@pxref{Top, GNU Mes Reference Manual,, mes, GNU Mes}, a Scheme interpreter +and C compiler in Scheme). Neither MesCC-Tools nor Mes can be fully +bootstrapped yet and thus we inject them as binary seeds. We call this the +Reduced Binary Seed bootstrap, as it has halved the size of our bootstrap +binaries! Also, it has eliminated the C compiler binary; i686-linux and +x86_64-linux Guix packages are now bootstrapped without any binary C compiler. + +Work is ongoing to make MesCC-Tools and Mes fully bootstrappable and we are +also looking at any other bootstrap binaries. Your help is welcome! @node Porting @chapter Porting to a New Platform |