/* * 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); }