Re: [PATCH] eliminate warnings in generated module files

From: Rusty Russell (rusty@rustcorp.com.au)
Date: Wed Feb 19 2003 - 19:01:50 EST


In message <20030218221656.A23989@twiddle.net> you write:
> gcc version 2.95.4 20011002 (Debian prerelease)
>
> Seems to work, both wrt the warning message and
> honoring the section directive.

Excellent. For Linus's (and Kai's) benefit, this is Richard's patch
again. Thanks Richard!

From: Richard Henderson <rth@twiddle.net>

===== include/linux/compiler.h 1.10 vs edited =====
--- 1.10/include/linux/compiler.h Tue Dec 31 15:10:18 2002
+++ edited/include/linux/compiler.h Tue Feb 18 17:39:38 2003
@@ -25,6 +25,23 @@
 #define __deprecated
 #endif
 
+/*
+ * Allow us to avoid 'defined but not used' warnings on functions and data,
+ * as well as force them to be emitted to the assembly file.
+ *
+ * As of gcc 3.3, static functions that are not marked with attribute((used))
+ * may be elided from the assembly file. As of gcc 3.3, static data not so
+ * marked will not be elided, but this may change in a future gcc version.
+ *
+ * In prior versions of gcc, such functions and data would be emitted, but
+ * would be warned about except with attribute((unused)).
+ */
+#if __GNUC__ == 3 && __GNUC_MINOR__ >= 3 || __GNUC__ > 3
+#define __attribute_used__ __attribute__((__used__))
+#else
+#define __attribute_used__ __attribute__((__unused__))
+#endif
+
 /* This macro obfuscates arithmetic on a variable address so that gcc
    shouldn't recognize the original var, and make assumptions about it */
 #define RELOC_HIDE(ptr, off) \
===== scripts/modpost.c 1.7 vs edited =====
--- 1.7/scripts/modpost.c Sun Feb 16 17:42:07 2003
+++ edited/scripts/modpost.c Tue Feb 18 17:41:54 2003
@@ -384,6 +384,7 @@
 {
         buf_printf(b, "#include <linux/module.h>\n");
         buf_printf(b, "#include <linux/vermagic.h>\n");
+ buf_printf(b, "#include <linux/compiler.h>\n");
         buf_printf(b, "\n");
         buf_printf(b, "const char vermagic[]\n");
         buf_printf(b, "__attribute__((section(\"__vermagic\"))) =\n");
@@ -449,6 +450,7 @@
 
         buf_printf(b, "\n");
         buf_printf(b, "static const char __module_depends[]\n");
+ buf_printf(b, "__attribute_used__\n");
         buf_printf(b, "__attribute__((section(\".modinfo\"))) =\n");
         buf_printf(b, "\"depends=");
         for (s = mod->unres; s; s = s->next) {

--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
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