Messages in this thread Patch in this message | | | From | Robin Getz <> | Subject | early_printk accessing __log_buf | Date | Wed, 18 Jul 2007 17:56:43 -0400 |
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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?
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