From 69bc8d386aebbd91a6bb44b6d33f77c8dfa9ed8c Mon Sep 17 00:00:00 2001
From: Masahiro Yamada <masahiroy@kernel.org>
Date: Fri, 26 Mar 2021 03:54:09 +0900
Subject: kbuild: generate Module.symvers only when vmlinux exists

The external module build shows the following warning if Module.symvers
is missing in the kernel tree.

  WARNING: Symbol version dump "Module.symvers" is missing.
           Modules may not have dependencies or modversions.

I think this is an important heads-up because the resulting modules may
not work as expected. This happens when you did not build the entire
kernel tree, for example, you might have prepared the minimal setups
for external modules by 'make defconfig && make modules_preapre'.

A problem is that 'make modules' creates Module.symvers even without
vmlinux. In this case, that warning is suppressed since Module.symvers
already exists in spite of its incomplete content.

The incomplete (i.e. invalid) Module.symvers should not be created.

This commit changes the second pass of modpost to dump symbols into
modules-only.symvers. The final Module.symvers is created by
concatenating vmlinux.symvers and modules-only.symvers if both exist.

Module.symvers is supposed to collect symbols from both vmlinux and
modules. It might be a bit confusing, and I am not quite sure if it
is an official interface, but presumably it is difficult to rename it
because some tools (e.g. kmod) parse it.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---
 .gitignore | 1 +
 1 file changed, 1 insertion(+)

(limited to '.gitignore')

diff --git a/.gitignore b/.gitignore
index 3adea59847ce..df8d3146a43f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -57,6 +57,7 @@ modules.order
 /tags
 /TAGS
 /linux
+/modules-only.symvers
 /vmlinux
 /vmlinux.32
 /vmlinux.map
-- 
cgit