On 14/03/13 04:00, Rusty Russell wrote:
> From: Rusty Russell <ru...@rustcorp.com.au>
> Subject: CONFIG_SYMBOL_PREFIX: cleanup.
> 
> We have CONFIG_SYMBOL_PREFIX, which three archs define to the string
> "_".  But Al Viro broke this in "consolidate cond_syscall and
> SYSCALL_ALIAS declarations" (in linux-next), and he's not the first to
> do so.
> 
> Using CONFIG_SYMBOL_PREFIX is awkward, since we usually just want to
> prefix it so something.  So various places define helpers which are
> defined to nothing if CONFIG_SYMBOL_PREFIX isn't set:
> 
> 1) include/asm-generic/unistd.h defines __SYMBOL_PREFIX.
> 2) include/asm-generic/vmlinux.lds.h defines VMLINUX_SYMBOL(sym)
> 3) include/linux/export.h defines MODULE_SYMBOL_PREFIX.
> 4) include/linux/kernel.h defines SYMBOL_PREFIX (which differs from #7)
> 5) kernel/modsign_certificate.S defines ASM_SYMBOL(sym)
> 6) scripts/modpost.c defines MODULE_SYMBOL_PREFIX
> 7) scripts/Makefile.lib defines SYMBOL_PREFIX on the commandline if
>    CONFIG_SYMBOL_PREFIX is set, so that we have a non-string version
>    for pasting.
> 
> (arch/h8300/include/asm/linkage.h defines SYMBOL_NAME(), too).
> 
> Let's solve this properly:
> 1) No more generic prefix, just CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX.
> 2) Make linux/export.h usable from asm.
> 3) Define VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR().
> 4) Make everyone use them.
> 
> Signed-off-by: Rusty Russell <ru...@rustcorp.com.au>

Reviewed-by: James Hogan <james.ho...@imgtec.com>
Tested-by: James Hogan <james.ho...@imgtec.com> (metag)

The only other special case of symbol prefixing I'm aware of is in
scripts/genksyms/genksyms.c. It makes the decision at runtime based
on the --arch=$ARCH argument, and is the only use of the arch argument:

>       if ((strcmp(arch, "h8300") == 0) || (strcmp(arch, "blackfin") == 0) ||
>           (strcmp(arch, "metag") == 0))
>               mod_prefix = "_";

Does the patch below look reasonable in addition to your patch?
(Note: I'm not sure if genksyms is only used internally or whether
it's API should be kept stable?).

Thanks
James

Subject: [PATCH] genksyms: pass symbol-prefix instead of arch

Pass symbol-prefix to genksyms instead of arch, so that the decision
what symbol prefix to use is kept in one place.

Basically genksyms used to take a -a $ARCH argument and it used that to
determine whether to add an underscore symbol prefix. It's now changed
to take a -s $SYMBOL_PREFIX argument so that the caller decides whether
a symbol prefix is required. The build system then uses
CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX to determine whether to pass the
argument.

Signed-off-by: James Hogan <james.ho...@imgtec.com>
---
 scripts/Makefile.build      |  3 ++-
 scripts/genksyms/genksyms.c | 18 +++++++-----------
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 0e801c3..d5d859c 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -211,7 +211,8 @@ $(obj)/%.i: $(src)/%.c FORCE
 
 cmd_gensymtypes =                                                           \
     $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
-    $(GENKSYMS) $(if $(1), -T $(2)) -a $(ARCH)                              \
+    $(GENKSYMS) $(if $(1), -T $(2))                                         \
+     $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX))             \
      $(if $(KBUILD_PRESERVE),-p)                                            \
      -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
 
diff --git a/scripts/genksyms/genksyms.c b/scripts/genksyms/genksyms.c
index d25e4a1..88632df 100644
--- a/scripts/genksyms/genksyms.c
+++ b/scripts/genksyms/genksyms.c
@@ -45,7 +45,6 @@ int in_source_file;
 
 static int flag_debug, flag_dump_defs, flag_reference, flag_dump_types,
           flag_preserve, flag_warnings;
-static const char *arch = "";
 static const char *mod_prefix = "";
 
 static int errors;
@@ -731,7 +730,7 @@ static void genksyms_usage(void)
 {
        fputs("Usage:\n" "genksyms [-adDTwqhV] > /path/to/.tmp_obj.ver\n" "\n"
 #ifdef __GNU_LIBRARY__
-             "  -a, --arch            Select architecture\n"
+             "  -s, --symbol-prefix   Select symbol prefix\n"
              "  -d, --debug           Increment the debug level (repeatable)\n"
              "  -D, --dump            Dump expanded symbol defs (for debugging 
only)\n"
              "  -r, --reference file  Read reference symbols from a file\n"
@@ -742,7 +741,7 @@ static void genksyms_usage(void)
              "  -h, --help            Print this message\n"
              "  -V, --version         Print the release version\n"
 #else                          /* __GNU_LIBRARY__ */
-             "  -a                    Select architecture\n"
+             "  -s                    Select symbol prefix\n"
              "  -d                    Increment the debug level (repeatable)\n"
              "  -D                    Dump expanded symbol defs (for debugging 
only)\n"
              "  -r file               Read reference symbols from a file\n"
@@ -763,7 +762,7 @@ int main(int argc, char **argv)
 
 #ifdef __GNU_LIBRARY__
        struct option long_opts[] = {
-               {"arch", 1, 0, 'a'},
+               {"symbol-prefix", 1, 0, 's'},
                {"debug", 0, 0, 'd'},
                {"warnings", 0, 0, 'w'},
                {"quiet", 0, 0, 'q'},
@@ -776,14 +775,14 @@ int main(int argc, char **argv)
                {0, 0, 0, 0}
        };
 
-       while ((o = getopt_long(argc, argv, "a:dwqVDr:T:ph",
+       while ((o = getopt_long(argc, argv, "s:dwqVDr:T:ph",
                                &long_opts[0], NULL)) != EOF)
 #else                          /* __GNU_LIBRARY__ */
-       while ((o = getopt(argc, argv, "a:dwqVDr:T:ph")) != EOF)
+       while ((o = getopt(argc, argv, "s:dwqVDr:T:ph")) != EOF)
 #endif                         /* __GNU_LIBRARY__ */
                switch (o) {
-               case 'a':
-                       arch = optarg;
+               case 's':
+                       mod_prefix = optarg;
                        break;
                case 'd':
                        flag_debug++;
@@ -826,9 +825,6 @@ int main(int argc, char **argv)
                        genksyms_usage();
                        return 1;
                }
-       if ((strcmp(arch, "h8300") == 0) || (strcmp(arch, "blackfin") == 0) ||
-           (strcmp(arch, "metag") == 0))
-               mod_prefix = "_";
        {
                extern int yydebug;
                extern int yy_flex_debug;
-- 
1.8.1.2


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