This repository is the RISC-V GNU Compiler Toolchain build system. It provides the infrastructure to build cross-compilation toolchains targeting RISC-V architectures (RV32/RV64) with various C libraries (newlib, picolibc, glibc, musl, uClibc). The codebase consists of autotools-based configure scripts, Makefile templates, vendored Linux kernel UAPI headers for RISC-V, CI workflows, and test infrastructure including DejaGnu board configurations and regression test allowlists. It is not an end-user application but a build orchestration project that compiles GCC, binutils, and associated libraries from source. The architecture is a classic GNU autotools build system with submodule dependencies. Key entry points are the top-level `configure` script and `Makefile.in`, which drive the build of all toolchain components. The repository also includes scripts for running tests on QEMU and Spike simulators, and CI pipelines for continuous integration and nightly releases.