warn about use of uninstalled kernel headers

User applications frequently hit problems when they try to use the kernel headers directly, rather than the exported headers. This adds an explicit warning for this case, and points to a URL holding an explanation of why this is wrong and what to do about it. Signed-off-by: Arnd Bergmann <[email protected]> Signed-off-by: Sam Ravnborg <[email protected]>
mna · Oct 11, 2009 · c01226c · c01226c
1 parent 17c5ca9
commit c01226c
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Showing 2 changed files with 7 additions and 1 deletion.
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
@@ -659,6 +659,12 @@ extern int do_sysinfo(struct sysinfo *info);
 
 #endif /* __KERNEL__ */
 
+#ifndef __EXPORTED_HEADERS__
+#ifndef __KERNEL__
+#warning Attempt to use kernel headers from user space, see http://kernelnewbies.org/KernelHeaders
+#endif /* __KERNEL__ */
+#endif /* __EXPORTED_HEADERS__ */
+
 #define SI_LOAD_SHIFT	16
 struct sysinfo {
 	long uptime;			/* Seconds since boot */

diff --git a/scripts/headers_install.pl b/scripts/headers_install.pl
@@ -20,7 +20,7 @@
 
 my ($readdir, $installdir, $arch, @files) = @ARGV;
 
-my $unifdef = "scripts/unifdef -U__KERNEL__";
+my $unifdef = "scripts/unifdef -U__KERNEL__ -D__EXPORTED_HEADERS__";
 
 foreach my $file (@files) {
 	local *INFILE;