On Wed, 18 Jul 2007 17:56:43 -0400 Robin Getz <[EMAIL PROTECTED]> wrote:
> 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... Being able to get at the log buffer from external debug-style code is a fairly common requirement. > =================================================================== > --- 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 */ > erk. There isn't much point in making something externally accessible without also declaring it in a header file. And callers will need to be able to get at log_buf_len too, I guess. I'd suggest that any interface into here should be via function calls, not via direct access to printk internals: think up some nice copy_me_some_of_the_log_buffer() interface. - 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/