linux/arch/tile/kernel/early_printk.c
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   1/*
   2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
   3 *
   4 *   This program is free software; you can redistribute it and/or
   5 *   modify it under the terms of the GNU General Public License
   6 *   as published by the Free Software Foundation, version 2.
   7 *
   8 *   This program is distributed in the hope that it will be useful, but
   9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11 *   NON INFRINGEMENT.  See the GNU General Public License for
  12 *   more details.
  13 */
  14
  15#include <linux/console.h>
  16#include <linux/kernel.h>
  17#include <linux/init.h>
  18#include <linux/string.h>
  19#include <linux/irqflags.h>
  20#include <linux/printk.h>
  21#include <asm/setup.h>
  22#include <hv/hypervisor.h>
  23
  24static void early_hv_write(struct console *con, const char *s, unsigned n)
  25{
  26        hv_console_write((HV_VirtAddr) s, n);
  27}
  28
  29static struct console early_hv_console = {
  30        .name =         "earlyhv",
  31        .write =        early_hv_write,
  32        .flags =        CON_PRINTBUFFER,
  33        .index =        -1,
  34};
  35
  36/* Direct interface for emergencies */
  37static int early_console_complete;
  38
  39void early_panic(const char *fmt, ...)
  40{
  41        va_list ap;
  42        arch_local_irq_disable_all();
  43        va_start(ap, fmt);
  44        early_printk("Kernel panic - not syncing: ");
  45        early_vprintk(fmt, ap);
  46        early_console->write(early_console, "\n", 1);
  47        va_end(ap);
  48        dump_stack();
  49        hv_halt();
  50}
  51
  52static int __initdata keep_early;
  53
  54static int __init setup_early_printk(char *str)
  55{
  56        if (early_console)
  57                return 1;
  58
  59        if (str != NULL && strncmp(str, "keep", 4) == 0)
  60                keep_early = 1;
  61
  62        early_console = &early_hv_console;
  63        register_console(early_console);
  64
  65        return 0;
  66}
  67
  68void __init disable_early_printk(void)
  69{
  70        early_console_complete = 1;
  71        if (!early_console)
  72                return;
  73        if (!keep_early) {
  74                early_printk("disabling early console\n");
  75                unregister_console(early_console);
  76                early_console = NULL;
  77        } else {
  78                early_printk("keeping early console\n");
  79        }
  80}
  81
  82void warn_early_printk(void)
  83{
  84        if (early_console_complete || early_console)
  85                return;
  86        early_printk("\
  87Machine shutting down before console output is fully initialized.\n\
  88You may wish to reboot and add the option 'earlyprintk' to your\n\
  89boot command line to see any diagnostic early console output.\n\
  90");
  91}
  92
  93early_param("earlyprintk", setup_early_printk);
  94