x86: config option to disable info from decompression of the kernel

This patch allows the disabling of decompression messages during
x86 bootup.

Signed-off-by: Ben Collins <ben.collins@canonical.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/Kconfig.debug

@@ -16,6 +16,14 @@ config NONPROMISC_DEVMEM
 	  obviously disasterous, but specific access can be used by people
 	  debugging the kernel.
 
+config X86_VERBOSE_BOOTUP
+	bool "Enable verbose x86 bootup info messages"
+	default y
+	help
+	  Enables the informational output from the decompression stage
+	  (e.g. bzImage) of the boot. If you disable this you will still
+	  see errors. Disable this if you want silent bootup.
+
 config EARLY_PRINTK
 	bool "Early printk" if EMBEDDED
 	default y

arch/x86/boot/compressed/misc.c

@@ -202,7 +202,8 @@ static void free(void *where);
 static void *memset(void *s, int c, unsigned n);
 static void *memcpy(void *dest, const void *src, unsigned n);
 
-static void putstr(const char *);
+static void __putstr(int, const char *);
+#define putstr(__x)  __putstr(0, __x)
 
 #ifdef CONFIG_X86_64
 #define memptr long
@@ -266,11 +267,16 @@ static void scroll(void)
 		vidmem[i] = ' ';
 }
 
-static void putstr(const char *s)
+static void __putstr(int error, const char *s)
 {
 	int x, y, pos;
 	char c;
 
+#ifndef CONFIG_X86_VERBOSE_BOOTUP
+	if (!error)
+		return;
+#endif
+
 #ifdef CONFIG_X86_32
 	if (real_mode->screen_info.orig_video_mode == 0 &&
 	    lines == 0 && cols == 0)
@@ -363,9 +369,9 @@ static void flush_window(void)
 
 static void error(char *x)
 {
-	putstr("\n\n");
-	putstr(x);
-	putstr("\n\n -- System halted");
+	__putstr(1, "\n\n");
+	__putstr(1, x);
+	__putstr(1, "\n\n -- System halted");
 
 	while (1)
 		asm("hlt");