From: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Date: Sun, 6 Dec 2009 02:07:03 +0000 (-0200)
Subject: Module parameters.
X-Git-Tag: v1.9.0
X-Git-Url: http://git.cascardo.info/?p=cascardo%2Fkernel%2Fsamples%2F01.hello%2F.git;a=commitdiff_plain;h=9b2e34b7ae5d50e8e2a20bb7f74270834fabe2a8

Module parameters.
---

diff --git a/hello.c b/hello.c
index 327ee34..b5c0a6d 100644
--- a/hello.c
+++ b/hello.c
@@ -14,11 +14,18 @@ MODULE_LICENSE("GPL");
 #define SUBJECT "world"
 #endif
 
+static char *subject = SUBJECT;
+
+/* Define subject as a char pointer parameter. */
+module_param(subject, charp, 0664);
+/* Parameter description. */
+MODULE_PARM_DESC(subject, "Subject to say hello to.");
+
 /* Our init function: returns 0 if successfull, an error code, otherwise. */
 static int __init hello_init(void)
 {
 	/* printk is just like printf, but without floating point support. */
-	printk(KERN_ALERT "Hello, " SUBJECT "!\n");
+	printk(KERN_ALERT "Hello, %s!\n", subject);
 	return 0;
 }
 
@@ -26,7 +33,7 @@ static int __init hello_init(void)
 static void __exit hello_exit(void)
 {
 	/* KERN_ALERT is a string macro prepended to our message. */
-	printk(KERN_ALERT "Goodbye, cruel " SUBJECT "!\n");
+	printk(KERN_ALERT "Goodbye, cruel %s!\n", subject);
 }
 
 /* Here, we declare our module init and exit functions. */