Files
RedBear-OS/local/recipes/dev/libclc/source/libc/docs/porting.rst
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vasilito cb424d7448 build: static patch-sanity linter (shift-left the malformed-patch class)
verify-patch-sanity.py validates every active recipe .patch has internally-
consistent hunk line counts — catching the 'malformed patch at line N' failure
at commit/CI/preflight time instead of hours into a cook. This cycle hit that
class three times (qtwaylandscanner, sddm, xwayland), each only discovered when
cookbook tried to apply the patch.

Running it across the repo found 29 latent malformed patches (validated against
GNU patch: e.g. relibc/P3-sysv-ipc reproduces 'malformed patch at line 22').
They were harmless only because they sit in vendored recipes (baked, not re-
applied) — but would fail on any version-bump re-derivation. --fix recounts the
hunk headers (body untouched) and repaired all 29.

Wired into build-preflight.sh (Phase 1.0D) and redbear-ci.yml, with a unit test
(test-patch-sanity.sh). Skips archived/legacy trees and unvalidatable formats
(empty placeholders, bare-@@ git hunks).
2026-08-01 05:13:02 +03:00

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.. _porting:
=======================================
Bringup on a New OS or Architecture
=======================================
.. contents:: Table of Contents
:depth: 4
:local:
CI builders
===========
If you are contributing a port for an operating system or architecture which
is not covered by existing CI builders, you will also have to present a plan
for testing and contribute a CI builder. See
`this guide <https://llvm.org/docs/HowToAddABuilder.html>`_ for information
on how to add new builders to the
`LLVM buildbot <https://lab.llvm.org/buildbot>`_.
You will either have to extend the existing
`Linux script <https://github.com/llvm/llvm-zorg/blob/main/zorg/buildbot/builders/annotated/libc-linux.py>`_
and/or
`Windows script <https://github.com/llvm/llvm-zorg/blob/main/zorg/buildbot/builders/annotated/libc-windows.py>`_
or add a new script for your operating system.
An OS specific config directory
===============================
If you are starting to bring up LLVM's libc on a new operating system, the first
step is to add a directory for that OS in the ``libc/config`` directory. Both
`Linux <https://github.com/llvm/llvm-project/tree/main/libc/config/linux>`_ and
`Windows <https://github.com/llvm/llvm-project/tree/main/libc/config/windows>`_,
the two operating systems on which LLVM's libc is being actively developed,
have their own config directory.
.. note:: Windows development is not as active as the development on Linux.
There is a
`Darwin <https://github.com/llvm/llvm-project/tree/main/libc/config/darwin>`_
config also which is in a similar state as Windows.
.. note:: LLVM's libc is being brought up on the
`Fuchsia <https://fuchsia.dev/>`_ operating system also. However, there is no
config directory for Fuchsia as the bring up is being done in the Fuchsia
source tree.
Architecture Subdirectory
=========================
There are parts of the libc which are implemented differently for different
architectures. The simplest example of this is the ``syscall`` function and
its internal implementation - its Linux implementation differs for different
architectures. Since a large part of the libc makes use of syscalls (or an
equivalent on non-Linux like platforms), it might be simpler and convenient to
bring up the libc for one architecture at a time. In such cases, wherein the
support surface of LLVM's libc differs for each target architecture, one will
have to add a subdirectory (within the config directory of the operating
system) for each target architecture, and list the relevant config information
separately in those subdirectories. For example, for Linux, the x86_64 and
aarch64 configs are in separate directories, named
`x86_64 <https://github.com/llvm/llvm-project/tree/main/libc/config/linux/x86_64>`_
and `aarch64 <https://github.com/llvm/llvm-project/tree/main/libc/config/linux/aarch64>`_.
The libc CMake machinery looks for subdirectories named after the target
architecture.
The entrypoints.txt file
========================
One of the important pieces of config information is listed in a file named
``entrypoints.txt``. This file lists the targets for the entrypoints (see
:ref:`entrypoints`) you want to include in the static archive of the libc (for
the :ref:`overlay_mode` and/or the :ref:`full_host_build`.) If you are doing an
architecture specific bring up, then an ``entrypoints.txt`` file should be
created in the architecture subdirectory for each architecture. Else, having a
single ``entrypoints.txt`` in the operating system directory is sufficient.
The Linux config has an ``entrypoint.txt`` for each individual target
architecture separately: `aarch64 <https://github.com/llvm/llvm-project/tree/main/libc/config/linux/aarch64>`_,
`arm32 <https://github.com/llvm/llvm-project/tree/main/libc/config/linux/arm>`_ and
`x86_64 <https://github.com/llvm/llvm-project/tree/main/libc/config/linux/x86_64>`_. On the
other hand, the Windows config has a single ``entrypoints.txt``
`file <https://github.com/llvm/llvm-project/tree/main/libc/config/windows/entrypoints.txt>`_.
A typical bring up procedure will normally bring up a small group of entrypoints
at a time. The usual practice is to progressively add the targets for those
entrypoints to the ``entrypoints.txt`` file as they are being brought up. The
same is the case if one is implementing a new entrypoint - the target for the
new entrypoint should be added to the relevant ``entrypoints.txt`` file. If
the implementation of the new entrypoint supports multiple operating systems and
target architectures, then multiple ``entrypoints.txt`` files will have to be
updated.
The headers.txt file
====================
Another important piece of config information is listed in a file named
``headers.txt``. It lists the targets for the set of public headers that are
provided by the libc. This is relevant only if the libc is to be used in the
:ref:`full_host_build` on the target operating system and architecture. As with
the ``entrypoints.txt`` file, one ``headers.txt`` file should be listed for
each individual target architecture if you are doing an architecture specific
bring up. The Linux config has ``headers.txt`` file listed separately for the
`aarch64 <https://github.com/llvm/llvm-project/tree/main/libc/config/linux/aarch64>`_
config and the
`x86_64 <https://github.com/llvm/llvm-project/tree/main/libc/config/linux/x86_64>`_
config.