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    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
    -
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