[PATCH] Re: kernel/printk.c: increasing the buffer size to capture devfsd debug messages.

[Robert Read <rread@datarithm.net>]

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On Tue, Feb 20, 2001 at 01:37:16PM -0600, Thomas Dodd wrote:
> Robert Read wrote:
> > 
> > On Wed, Feb 21, 2001 at 02:30:08AM +0900, Ishikawa wrote:
> > >
> > > Has anyone tried 128K buffer size in kernel/printk.c
> > > and still have the kernel boot (without
> > > hard to notice memory corruption problems  and other subtle bugs)?
> > > Any hints and tips will be appreciated.
> > 
> > I have used 128k and larger buffer sizes, and I just noticed this
> > fragment in the RedHat Tux Webserver patch.  It creates a 2MB buffer:
> 
> I think this should be a config option.

Ok, here is a simple patch to add a config option, I'm compiling it
now, so it's not tested yet.  One question: what is the best way to
force this option to be a power of 2?

robert

[-- Attachment #2: printk-buflen.patch --]
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diff -ru linux-2.4.2-pre4/arch/i386/config.in linux-2.4.2-pre4-logbuf/arch/i386/config.in
--- linux-2.4.2-pre4/arch/i386/config.in	Mon Jan  8 13:27:56 2001
+++ linux-2.4.2-pre4-logbuf/arch/i386/config.in	Tue Feb 20 12:10:19 2001
@@ -366,4 +366,5 @@
 
 #bool 'Debug kmalloc/kfree' CONFIG_DEBUG_MALLOC
 bool 'Magic SysRq key' CONFIG_MAGIC_SYSRQ
+int 'Printk buffer size (must be power of 2)' CONFIG_PRINTK_BUF_LEN 16384
 endmenu
Only in linux-2.4.2-pre4-logbuf/arch/i386: config.in~
Only in linux-2.4.2-pre4-logbuf/include: asm
Only in linux-2.4.2-pre4-logbuf/include/linux: autoconf.h
Only in linux-2.4.2-pre4-logbuf/include/linux: modules
diff -ru linux-2.4.2-pre4/kernel/printk.c linux-2.4.2-pre4-logbuf/kernel/printk.c
--- linux-2.4.2-pre4/kernel/printk.c	Tue Feb 20 11:56:31 2001
+++ linux-2.4.2-pre4-logbuf/kernel/printk.c	Tue Feb 20 11:59:35 2001
@@ -23,7 +23,11 @@
 
 #include <asm/uaccess.h>
 
-#define LOG_BUF_LEN	(16384)
+#ifdef CONFIG_PRINTK_BUF_LEN
+# define LOG_BUF_LEN   (CONFIG_PRINTK_BUF_LEN)
+#else
+# define LOG_BUF_LEN   (16384)
+#endif   
 #define LOG_BUF_MASK	(LOG_BUF_LEN-1)
 
 static char buf[1024];