[RFC PATCH 6/6] Documentation: describe building tools with the kernel

[Sasha Levin <sashal@kernel.org>]

Mention CONFIG_TOOLS_BUILD and "make tools_build" in the submit
checklist, ask for libc-only selftests to be added to tools/Kconfig,
and note that USERCFLAGS and USERLDFLAGS also apply to the tools.

Assisted-by: LLM
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 Documentation/dev-tools/kselftest.rst      | 4 ++++
 Documentation/kbuild/kbuild.rst            | 5 ++++-
 Documentation/process/submit-checklist.rst | 5 +++++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/Documentation/dev-tools/kselftest.rst b/Documentation/dev-tools/kselftest.rst
index 64c0ec7428a27..407d539e49b01 100644
--- a/Documentation/dev-tools/kselftest.rst
+++ b/Documentation/dev-tools/kselftest.rst
@@ -315,6 +315,10 @@ Contributing new tests (details)
 
     TARGETS += android
 
+ * If the test builds with only a C library, add an entry for it to the
+   "Kernel selftests" menu in tools/Kconfig and to tools/Makefile.kbuild,
+   so that it is built together with the kernel.
+
  * All changes should pass::
 
     kselftest-{all,install,clean,gen_tar}
diff --git a/Documentation/kbuild/kbuild.rst b/Documentation/kbuild/kbuild.rst
index 5a9013bacfb75..3e8e076a262fa 100644
--- a/Documentation/kbuild/kbuild.rst
+++ b/Documentation/kbuild/kbuild.rst
@@ -114,12 +114,15 @@ Additional libraries to link against when building host programs.
 
 USERCFLAGS
 ----------
-Additional options used for $(CC) when compiling userprogs.
+Additional options used for $(CC) when compiling userprogs and the tools
+selected in tools/Kconfig.
 
 USERLDFLAGS
 -----------
 Additional options used for $(LD) when linking userprogs. userprogs are linked
 with CC, so $(USERLDFLAGS) should include "-Wl," prefix as applicable.
+The tools selected in tools/Kconfig get these options on the compiler
+command line.
 
 KBUILD_KCONFIG
 --------------
diff --git a/Documentation/process/submit-checklist.rst b/Documentation/process/submit-checklist.rst
index beb7f94279fdb..9857b05824c2d 100644
--- a/Documentation/process/submit-checklist.rst
+++ b/Documentation/process/submit-checklist.rst
@@ -91,6 +91,11 @@ Build your code
      Use ``make htmldocs`` or ``make pdfdocs`` to check the build and
      fix any issues.
 
+  e) Changes to tools/ or to UAPI headers do not break the userspace tools
+     selected by ``CONFIG_TOOLS_BUILD``. ``allmodconfig`` turns it on when
+     the compiler can link glibc programs for the target (currently x86_64
+     and arm64), and ``make tools_build`` builds only the tools.
+
 2) Builds on multiple CPU architectures by using local cross-compile tools
    or some other build farm.
    Note that testing against architectures of different word sizes
-- 
2.53.0