kbuild: do not read $(KBUILD_EXTMOD)/Module.symvers

Since commit 040fcc819a2e ("kbuild: improved modversioning support for
external modules"), the external module build reads Module.symvers in
the directory of the module itself, then dumps symbols back into it.
It accumulates stale symbols in the file when you build an external
module incrementally.

The idea behind it was, as the commit log explained, you can copy
Modules.symvers from one module to another when you need to pass symbol
information between two modules. However, the manual copy of the file
sounds questionable to me, and containing stale symbols is a downside.

Some time later, commit 0d96fb20b7ed ("kbuild: Add new Kbuild variable
KBUILD_EXTRA_SYMBOLS") introduced a saner approach.

So, this commit removes the former one. Going forward, the external
module build dumps symbols into Module.symvers to be carried via
KBUILD_EXTRA_SYMBOLS, but never reads it automatically.

With the -I option removed, there is no one to set the external_module
flag unless KBUILD_EXTRA_SYMBOLS is passed. Now the -i option does it
instead.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

diff --git a/Documentation/kbuild/modules.rst b/Documentation/kbuild/modules.rst
index 774a998dcf370e8395d988aca75de224562ae16b..69fa48ee93d6ec5de3988e3a7450dda4652860c7 100644 (file)
--- a/Documentation/kbuild/modules.rst
+++ b/Documentation/kbuild/modules.rst
@@ -492,11 +492,8 @@ build.
        to the symbols from the kernel to check if all external symbols
        are defined. This is done in the MODPOST step. modpost obtains
        the symbols by reading Module.symvers from the kernel source
-       tree. If a Module.symvers file is present in the directory
-       where the external module is being built, this file will be
-       read too. During the MODPOST step, a new Module.symvers file
-       will be written containing all exported symbols that were not
-       defined in the kernel.
+       tree. During the MODPOST step, a new Module.symvers file will be
+       written containing all exported symbols from that external module.
 
 6.3 Symbols From Another External Module
 ----------------------------------------
@@ -504,7 +501,7 @@ build.
        Sometimes, an external module uses exported symbols from
        another external module. Kbuild needs to have full knowledge of
        all symbols to avoid spitting out warnings about undefined
-       symbols. Three solutions exist for this situation.
+       symbols. Two solutions exist for this situation.
 
        NOTE: The method with a top-level kbuild file is recommended
        but may be impractical in certain situations.
@@ -544,8 +541,8 @@ build.
                all symbols defined and not part of the kernel.
 
        Use "make" variable KBUILD_EXTRA_SYMBOLS
-               If it is impractical to copy Module.symvers from
-               another module, you can assign a space separated list
+               If it is impractical to add a top-level kbuild file,
+               you can assign a space separated list
                of files to KBUILD_EXTRA_SYMBOLS in your build file.
                These files will be loaded by modpost during the
                initialization of its symbol tables.

diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index 13842693c143f2a0bb5e744e9e78ce31df0b14de..20359c7887b3b0baad6389923e5043b53d368097 100644 (file)
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -50,7 +50,6 @@ MODPOST = scripts/mod/modpost                                         \
        $(if $(CONFIG_MODVERSIONS),-m)                                  \
        $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a)                        \
        $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile)                   \
-       $(if $(KBUILD_EXTMOD),-I $(modulesymfile))                      \
        $(if $(KBUILD_EXTMOD),$(addprefix -e ,$(KBUILD_EXTRA_SYMBOLS))) \
        $(if $(KBUILD_EXTMOD),-o $(modulesymfile))                      \
        $(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E)                  \

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index d2a30a7b3f07cc884889555948054acb911e1fc7..37fa1c65ee4de2f16b2be3a102fd3fe9d03fd00f 100644 (file)
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2561,7 +2561,7 @@ int main(int argc, char **argv)
 {
        struct module *mod;
        struct buffer buf = { };
-       char *kernel_read = NULL, *module_read = NULL;
+       char *kernel_read = NULL;
        char *dump_write = NULL, *files_source = NULL;
        int opt;
        int err;
@@ -2569,13 +2569,10 @@ int main(int argc, char **argv)
        struct ext_sym_list *extsym_iter;
        struct ext_sym_list *extsym_start = NULL;
 
-       while ((opt = getopt(argc, argv, "i:I:e:mnsT:o:awEd")) != -1) {
+       while ((opt = getopt(argc, argv, "i:e:mnsT:o:awEd")) != -1) {
                switch (opt) {
                case 'i':
                        kernel_read = optarg;
-                       break;
-               case 'I':
-                       module_read = optarg;
                        external_module = 1;
                        break;
                case 'e':
@@ -2620,8 +2617,6 @@ int main(int argc, char **argv)
 
        if (kernel_read)
                read_dump(kernel_read, 1);
-       if (module_read)
-               read_dump(module_read, 0);
        while (extsym_start) {
                read_dump(extsym_start->file, 0);
                extsym_iter = extsym_start->next;