Re: [PATCH] configurable LOG_BUF_SIZE

[Randy.Dunlap]

On Mon, 6 Jan 2003, Randy.Dunlap wrote:

| On Mon, 6 Jan 2003, Linus Torvalds wrote:
|
| |
| | On Mon, 6 Jan 2003, Tom Rini wrote:
| | >
| | > > Linus also told me that he's not crazy about this change.
| | >
| | > Maybe he would be, if it was cleaner than the current code in the end.
| | > :)
| |
| | No, the reason I'm not crazy about it is that I simply _hate_ having too
| | many user knobs to tweak. I don't like tweaking like that, it's just
| | disturbing.
| |---------------------------------------------------------------------------
| | I'd probably be happier if the current one didn't even _ask_ the user (or|
| | only asked the user if kernel debugging is enabled), and just silently   |
| | defaulted to the normal values.                                          |
| |---------------------------------------------------------------------------
|
| I'll be happy to move it there (later today)...

Hm.  Roman, Tomas, Sam-

Do any of you know how to write a kconfig item like Linus described
above (in the box)?

It's simple enough to have a config option that isn't available if
DEBUG_KERNEL is false, but how do I make default values for it
when it's false?
The config option must still exist in this case, but not be presented
to the user as a choice.

My attempt (for i386) is attached.  Applies to 2.5.54 + yesterday's
patch.  Are there better ways to do this?

Thanks,
-- 
~Randy

--- ./arch/i386/Kconfig%LGBUF	Wed Jan  1 19:21:10 2003
+++ ./arch/i386/Kconfig	Mon Jan  6 12:37:54 2003
@@ -1624,6 +1624,31 @@
 	  If you don't debug the kernel, you can say N, but we may not be able
 	  to solve problems without frame pointers.

+config LOG_BUF_SHIFT
+	int "Kernel log buffer size"
+	depends on DEBUG_KERNEL
+	default 17 if ARCH_S390
+	default 16 if X86_NUMAQ || IA64
+	default 15 if SMP
+	default 14
+	help
+	  Select kernel log buffer size as a power of 2.
+	  Defaults and Examples:
+	  	     17 (=> 128 KB for S/390)
+		     16 (=> 64 KB for x86 NUMAQ or IA-64)
+	             15 (=> 32 KB for SMP)
+	             14 (=> 16 KB for uniprocessor)
+		     13 (=>  8 KB)
+		     12 (=>  4 KB)
+
+config LOG_BUF_SHIFT
+	int
+	depends on !DEBUG_KERNEL
+	default 17 if ARCH_S390
+	default 16 if X86_NUMAQ || IA64
+	default 15 if SMP
+	default 14
+
 config X86_EXTRA_IRQS
 	bool
 	depends on X86_LOCAL_APIC || X86_VOYAGER
--- ./init/Kconfig%LGBUF	Mon Jan  6 11:52:14 2003
+++ ./init/Kconfig	Mon Jan  6 11:55:00 2003
@@ -98,51 +98,6 @@
 	  building a kernel for install/rescue disks or your system is very
 	  limited in memory.

-choice
-	prompt "Kernel log buffer size"
-	default LOG_BUF_SHIFT_17 if ARCH_S390
-	default LOG_BUF_SHIFT_16 if X86_NUMAQ || IA64
-	default LOG_BUF_SHIFT_15 if SMP
-	default LOG_BUF_SHIFT_14
-	help
-	  Select kernel log buffer size from this list (power of 2).
-	  Defaults:  17 (=> 128 KB for S/390)
-		     16 (=> 64 KB for x86 NUMAQ or IA-64)
-	             15 (=> 32 KB for SMP)
-	             14 (=> 16 KB for uniprocessor)
-
-config LOG_BUF_SHIFT_17
-	bool "128 KB"
-	default y if ARCH_S390
-
-config LOG_BUF_SHIFT_16
-	bool "64 KB"
-	default y if X86_NUMAQ || IA64
-
-config LOG_BUF_SHIFT_15
-	bool "32 KB"
-	default y if SMP
-
-config LOG_BUF_SHIFT_14
-	bool "16 KB"
-
-config LOG_BUF_SHIFT_13
-	bool "8 KB"
-
-config LOG_BUF_SHIFT_12
-	bool "4 KB"
-
-endchoice
-
-config LOG_BUF_SHIFT
-	int
-	default 17 if LOG_BUF_SHIFT_17=y
-	default 16 if LOG_BUF_SHIFT_16=y
-	default 15 if LOG_BUF_SHIFT_15=y
-	default 14 if LOG_BUF_SHIFT_14=y
-	default 13 if LOG_BUF_SHIFT_13=y
-	default 12 if LOG_BUF_SHIFT_12=y
-
 endmenu