From 228c92021dafa1e76f7d39ecf1af5a0f843940d0 Mon Sep 17 00:00:00 2001 From: cyan Date: Fri, 8 Nov 2024 15:23:04 +0000 Subject: migrate build system --- contrib/depends/description.md | 53 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 contrib/depends/description.md (limited to 'contrib/depends/description.md') diff --git a/contrib/depends/description.md b/contrib/depends/description.md new file mode 100644 index 0000000..74f9ef3 --- /dev/null +++ b/contrib/depends/description.md @@ -0,0 +1,53 @@ +This is a system of building and caching dependencies necessary for building Bitcoin. +There are several features that make it different from most similar systems: + +### It is designed to be builder and host agnostic + +In theory, binaries for any target OS/architecture can be created, from a +builder running any OS/architecture. In practice, build-side tools must be +specified when the defaults don't fit, and packages must be amended to work +on new hosts. For now, a build architecture of x86_64 is assumed, either on +Linux or OSX. + +### No reliance on timestamps + +File presence is used to determine what needs to be built. This makes the +results distributable and easily digestable by automated builders. + +### Each build only has its specified dependencies available at build-time. + +For each build, the sysroot is wiped and the (recursive) dependencies are +installed. This makes each build deterministic, since there will never be any +unknown files available to cause side-effects. + +### Each package is cached and only rebuilt as needed. + +Before building, a unique build-id is generated for each package. This id +consists of a hash of all files used to build the package (Makefiles, packages, +etc), and as well as a hash of the same data for each recursive dependency. If +any portion of a package's build recipe changes, it will be rebuilt as well as +any other package that depends on it. If any of the main makefiles (Makefile, +funcs.mk, etc) are changed, all packages will be rebuilt. After building, the +results are cached into a tarball that can be re-used and distributed. + +### Package build results are (relatively) deterministic. + +Each package is configured and patched so that it will yield the same +build-results with each consequent build, within a reasonable set of +constraints. Some things like timestamp insertion are unavoidable, and are +beyond the scope of this system. Additionally, the toolchain itself must be +capable of deterministic results. When revisions are properly bumped, a cached +build should represent an exact single payload. + +### Sources are fetched and verified automatically + +Each package must define its source location and checksum. The build will fail +if the fetched source does not match. Sources may be pre-seeded and/or cached +as desired. + +### Self-cleaning + +Build and staging dirs are wiped after use, and any previous version of a +cached result is removed following a successful build. Automated builders +should be able to build each revision and store the results with no further +intervention. -- cgit v1.2.3