linux-kernel - Re: [PATCH] Config option to disable info from decompression of the kernel

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Date:	Thu, 3 Jul 2008 14:36:42 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Ben Collins <ben.collins@...onical.com>
Cc:	kernel list <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] Config option to disable info from decompression of
	the kernel


* Ben Collins <ben.collins@...onical.com> wrote:

> I submitted a similar patch some time ago, but rightfully it didn't 
> get accepted, as it just disabled all output from the decompress stage 
> (without a boot time option to enable it).
> 
> This patch just disables the information output from this stage, but 
> not the error output.

> +config NO_BZ_CHATTER
> +	bool "Disable decompress info messages"
> +	default n
> +	help
> +	  Disables just the informational output from the decompression stage
> +	  (e.g. bzImage) of the boot. You will still see errors. Do this if you
> +	  want to cleanup the bootup process.

applied to tip/x86/setup - thanks Ben.

Note that i've flipped around the name (i.e. got rid of the 'NO_'), and 
i renamed it to the bit more generic X86_VERBOSE_BOOTUP config variable. 
We might want to make other output dependent on that flag, not just the 
decompressor messages. Find the commit below. (please double-check it)

	Ingo

----------------------->
commit 6bcb13b35a2ea39be6c7cc0292b8ad1191b1a748
Author: Ben Collins <ben.collins@...onical.com>
Date:   Wed Jun 18 14:04:35 2008 -0400

    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@...onical.com>
    Signed-off-by: Ingo Molnar <mingo@...e.hu>

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index ac1e31b..14abaa5 100644
--- a/arch/x86/Kconfig.debug
+++ b/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
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index d10e727..11629e9 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/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");
--
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