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/*
* kmsg dumper that ensures the OPAL console fully flushes panic messages
*
* Author: Russell Currey <ruscur@russell.cc>
*
* Copyright 2015 IBM Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*/
#include <linux/kmsg_dump.h>
#include <asm/opal.h>
#include <asm/opal-api.h>
/*
* Console output is controlled by OPAL firmware. The kernel regularly calls
* OPAL_POLL_EVENTS, which flushes some console output. In a panic state,
* however, the kernel no longer calls OPAL_POLL_EVENTS and the panic message
* may not be completely printed. This function does not actually dump the
* message, it just ensures that OPAL completely flushes the console buffer.
*/
static void kmsg_dump_opal_console_flush(struct kmsg_dumper *dumper,
enum kmsg_dump_reason reason)
{
/*
* Outside of a panic context the pollers will continue to run,
* so we don't need to do any special flushing.
*/
if (reason != KMSG_DUMP_PANIC)
return;
opal_flush_console(0);
}
static struct kmsg_dumper opal_kmsg_dumper = {
.dump = kmsg_dump_opal_console_flush
};
void __init opal_kmsg_init(void)
{
int rc;
/* Add our dumper to the list */
rc = kmsg_dump_register(&opal_kmsg_dumper);
if (rc != 0)
pr_err("opal: kmsg_dump_register failed; returned %d\n", rc);
}
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