kbuild: soften modpost checks when doing cross builds

The module alias support in the kernel have a consistency
check where it is checked that the size of a structure
in the kernel and on the build host are the same.
For cross builds this check does not make sense so detect
when we do cross builds and silently skip the check in these
situations.
This fixes a build bug for a wireless driver when cross building
for arm.

Acked-by: Michael Buesch <mb@bu3sch.de>
Tested-by: Gordon Farquharson <gordonfarquharson@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: stable@kernel.org

diff --git a/Makefile b/Makefile
index 7a4d34b91e032099d119adae92a0f347dc481901..1c4c8f87f6c582f51c44823b2614d4414927534d 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -189,7 +189,7 @@ SUBARCH := $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \
 # Alternatively CROSS_COMPILE can be set in the environment.
 # Default value for CROSS_COMPILE is not to prefix executables
 # Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
-
+export KBUILD_BUILDHOST := $(SUBARCH)
 ARCH           ?= $(SUBARCH)
 CROSS_COMPILE  ?=
 

diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index cfc004e04417e5126a75d53cc3ce3d04c8924c9b..2d20640854b7412bd46156f568a9a29443b6c0aa 100644 (file)
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -58,6 +58,9 @@ modules   := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o)))
 # Stop after building .o files if NOFINAL is set. Makes compile tests quicker
 _modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))
 
+ifneq ($(KBUILD_BUILDHOST),$(ARCH))
+        cross_build := 1
+endif
 
 # Step 2), invoke modpost
 #  Includes step 3,4
@@ -70,7 +73,8 @@ modpost = scripts/mod/modpost                    \
  $(if $(CONFIG_DEBUG_SECTION_MISMATCH),,-S)      \
  $(if $(CONFIG_MARKERS),-K $(kernelmarkersfile)) \
  $(if $(CONFIG_MARKERS),-M $(markersfile))      \
- $(if $(KBUILD_EXTMOD)$(KBUILD_MODPOST_WARN),-w)
+ $(if $(KBUILD_EXTMOD)$(KBUILD_MODPOST_WARN),-w) \
+ $(if $(cross_build),-c)
 
 quiet_cmd_modpost = MODPOST $(words $(filter-out vmlinux FORCE, $^)) modules
       cmd_modpost = $(modpost) -s

diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index 9ddf944cce290b7d38fc2982b852bc93d4c50001..348d8687b7c9cad167c6d631ce9e5f1c2038bdf0 100644 (file)
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -51,11 +51,13 @@ do {                                                            \
                 sprintf(str + strlen(str), "*");                \
 } while(0)
 
+unsigned int cross_build = 0;
 /**
  * Check that sizeof(device_id type) are consistent with size of section
  * in .o file. If in-consistent then userspace and kernel does not agree
  * on actual size which is a bug.
  * Also verify that the final entry in the table is all zeros.
+ * Ignore both checks if build host differ from target host and size differs.
  **/
 static void device_id_check(const char *modname, const char *device_id,
                            unsigned long size, unsigned long id_size,
@@ -64,6 +66,8 @@ static void device_id_check(const char *modname, const char *device_id,
        int i;
 
        if (size % id_size || size < id_size) {
+               if (cross_build != 0)
+                       return;
                fatal("%s: sizeof(struct %s_device_id)=%lu is not a modulo "
                      "of the size of section __mod_%s_device_table=%lu.\n"
                      "Fix definition of struct %s_device_id "

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 695b5d657cf59cc89ba1a4989d7052085e942abf..110cf243fa4e56d3749781c7b4703bf4c62ae9b7 100644 (file)
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2026,7 +2026,7 @@ int main(int argc, char **argv)
        int opt;
        int err;
 
-       while ((opt = getopt(argc, argv, "i:I:msSo:awM:K:")) != -1) {
+       while ((opt = getopt(argc, argv, "i:I:cmsSo:awM:K:")) != -1) {
                switch (opt) {
                case 'i':
                        kernel_read = optarg;
@@ -2035,6 +2035,9 @@ int main(int argc, char **argv)
                        module_read = optarg;
                        external_module = 1;
                        break;
+               case 'c':
+                       cross_build = 1;
+                       break;
                case 'm':
                        modversions = 1;
                        break;

diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 565c5872407e19e2cfd8c16a63a19be0fd358f47..09f58e33d227bf3fecb88d555f33cd52fc4375a7 100644 (file)
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -135,6 +135,7 @@ struct elf_info {
 };
 
 /* file2alias.c */
+extern unsigned int cross_build;
 void handle_moddevtable(struct module *mod, struct elf_info *info,
                        Elf_Sym *sym, const char *symname);
 void add_moddevtable(struct buffer *buf, struct module *mod);