Re: [PATCH] Re: kernel/printk.c: increasing the buffer size to capture devfsd debug messages.
On Tue, Feb 20, 2001 at 02:53:04PM -0600, Thomas Dodd wrote:
> Robert Read wrote:
>
> Why not just make the config option in Kbytes.
> and do:
>
> #define LOG_BUF_LEN (CONFIG_PRINTK_BUF_LEN * 1024)
>
This is good idea, but I believe LOG_BUF_LEN needs to be a power of
2. A bitmask is used in several places to wrap around the end of the
ring buffer. For example
#define LOG_BUF_MASK (LOG_BUF_LEN-1)
printk() {
log_buf[(log_start+log_size) & LOG_BUF_MASK] = *p;
}
I think LOG_BUF_LEN could be defined to round up (or down) at compile
time, but my post-lunch-sleepy brain can't think of the trick to do
it.
robert
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Re: [PATCH] Re: kernel/printk.c: increasing the buffer size to capture devfsd debug messages.
Thomas Dodd wrote: > > Robert Read wrote: > > > > 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? > > Why not just make the config option in Kbytes. > and do: > > #define LOG_BUF_LEN (CONFIG_PRINTK_BUF_LEN * 1024) > > since the config option has a default option and will > always be defined, is the #ifdef check really needed? Oops... It's not needed if all arch's have the config option added. Only parisc uses a different file, config.common instead of config.in Would this break any thing? -Thomas - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] Re: kernel/printk.c: increasing the buffer size to capture devfsd debug messages.
Robert Read wrote: > > 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? Why not just make the config option in Kbytes. and do: #define LOG_BUF_LEN (CONFIG_PRINTK_BUF_LEN * 1024) since the config option has a default option and will always be defined, is the #ifdef check really needed? -Thomas - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH] Re: kernel/printk.c: increasing the buffer size to capture devfsd debug messages.
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 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.inMon 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.cTue 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 -#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];
