lkml.org 
[lkml]   [2022]   [Apr]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 21/27] kbuild: record symbol versions in *.cmd files
Date
When CONFIG_MODVERSIONS=y, the output from genksyms is saved in
separate *.symversions files, and will be used much later when
CONFIG_LTO_CLANG=y because it is impossible to update LLVM bit code
here.

This approach is not robust because:

- *.symversions may or may not exist. If *.symversions does not
exist, we never know if it is missing for legitimate reason
(i.e. no EXPORT_SYMBOL) or something bad has happened (for
example, the user accidentally deleted it). Once it occurs,
it is not self-healing because *.symversions is generated
as a side effect of the build rule of the object.

- stale (i.e. invalid) *.symversions might be picked up if an
object is generated in a non-ordinary way, and corresponding
*.symversions (, which was generated by old builds) just happen
to exist.

A more robust approach is to save symbol versions in *.cmd files
because:

- *.cmd always exists (if the object is generated by if_changed
rule or friends). Even if the user accidentally deletes it,
it will be regenerated in the next build.

- *.cmd is always re-generated when the object is updated. This
avoid stale version information being picked up.

I will remove *.symversions later.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

scripts/Makefile.build | 2 ++
1 file changed, 2 insertions(+)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index f6a506318795..e03e85c90b26 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -175,6 +175,8 @@ gen_symversions = \
if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then \
$(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
> $@.symversions; \
+ echo >> $(dot-target).cmd ; \
+ sed 's/\(.*\) = \(.*\);/$(pound)\1=\2/' $@.symversions >> $(dot-target).cmd ; \
else \
rm -f $@.symversions; \
fi
--
2.32.0
\
 
 \ /
  Last update: 2022-04-24 21:14    [W:0.611 / U:0.112 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site