lkml.org 
[lkml]   [2007]   [Jul]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subjectearly_printk accessing __log_buf
Date
Quick question:

I am currently setting up an early_printk for the Blackfin - & I'm populating
an early fault interrupt handler at the same time. This allows things like
catching interrupts, or faults before the kernel has had a chance to
enable it's standard interrupt/fault handlers which happen midway
through the boot process.

I would like to be able to print out the standard __log_buf from my early
fault handler - so everyone can see where things are when they died. In
most situations - printk has dumped some info to the log_buf, and it is
normally handy to see figure out what is going on.

However - __log_buf & associated pointers are declared as static in
kernel/printk.c - so they can't be accessed by external files.

I would normally use do_syslog([23],...) to read from the buffer -
but these crashes happens before the kernel is fully initialized,
so spin_lock_irq, cond_resched, or wait_event_interruptible
will cause problems...

Although there are other solutions - I would prefer to just don't declare them
as static when EARLY_PRINTK is defined. This way if something bad happens -
everyone can dump out the standard buffers to assist in debugging...

===================================================================
--- linux-2.6.x/kernel/printk.c (revision 3400)
+++ linux-2.6.x/kernel/printk.c (working copy)
@@ -117,7 +117,12 @@

#ifdef CONFIG_PRINTK

+#ifdef CONFIG_EARLY_PRINTK
+char __log_buf[__LOG_BUF_LEN];
+#else
static char __log_buf[__LOG_BUF_LEN];
+#endif
+
static char *log_buf = __log_buf;
static int log_buf_len = __LOG_BUF_LEN;
static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */
Thoughts?

-Robin
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-07-18 23:55    [from the cache]
©2003-2011 Jasper Spaans