UBUNTU: SAUCE: (no-up) version: Implement version_signature proc file.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Tim Gardener <tim.gardner@canonical.com>

fs/proc/Makefile

@@ -30,3 +30,4 @@ proc-$(CONFIG_PROC_KCORE)	+= kcore.o
 proc-$(CONFIG_PROC_VMCORE)	+= vmcore.o
 proc-$(CONFIG_PRINTK)	+= kmsg.o
 proc-$(CONFIG_PROC_PAGE_MONITOR)	+= page.o
+proc-y	+= version_signature.o

fs/proc/version_signature.c

+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/utsname.h>
+
+static int version_signature_proc_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "%s\n", CONFIG_VERSION_SIGNATURE);
+	return 0;
+}
+
+static int version_signature_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, version_signature_proc_show, NULL);
+}
+
+static const struct file_operations version_signature_proc_fops = {
+	.open		= version_signature_proc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int __init proc_version_signature_init(void)
+{
+	proc_create("version_signature", 0, NULL, &version_signature_proc_fops);
+	return 0;
+}
+module_init(proc_version_signature_init);

init/Kconfig

@@ -208,6 +208,15 @@ config DEFAULT_HOSTNAME
 	  but you may wish to use a different default here to make a minimal
 	  system more usable with less configuration.
 
+config VERSION_SIGNATURE
+	string "Arbitrary version signature"
+	help
+	  This string will be created in a file, /proc/version_signature. It
+	  is useful in determining arbitrary data about your kernel. For instance,
+	  if you have several kernels of the same version, but need to keep track
+	  of a revision of the same kernel, but not affect it's ability to load
+	  compatible modules, this is the easiest way to do that.
+
 config SWAP
 	bool "Support for paging of anonymous memory (swap)"
 	depends on MMU && BLOCK

init/version.c

@@ -45,7 +45,11 @@ EXPORT_SYMBOL_GPL(init_uts_ns);
 /* FIXED STRINGS! Don't touch! */
 const char linux_banner[] =
 	"Linux version " UTS_RELEASE " (" LINUX_COMPILE_BY "@"
-	LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION "\n";
+	LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION
+#ifdef CONFIG_VERSION_SIGNATURE
+        " (" CONFIG_VERSION_SIGNATURE ")"
+#endif
+	"\n";
 
 const char linux_proc_banner[] =
 	"%s version %s"