Commit 56d611a0 authored by Marco Stornelli's avatar Marco Stornelli Committed by Linus Torvalds

char drivers: RAM oops/panic logger

Ramoops, like mtdoops, can log oops/panic information but in RAM.  It can
be used with persistent RAM for systems without flash support.  In
addition, for this systems, with this driver, it's no more needed add to
the kernel the mtd subsystem with advantage in footprint.

It can be used in a very easy way with persistent RAM for systems without
flash support.  For these systems, with this driver, it is no longer
required to cinlude mtd subsystem with an advantage in footprint.  In
addition, you can save flash space and store this information only in RAM.
Signed-off-by: default avatarMarco Stornelli <>
Cc: Simon Kagstrom <>
Cc: David Woodhouse <>
Cc; Anders Grafstrom <>
Cc: Yuasa Yoichi <>
Cc: Jamie Lokier <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent a747c5ab
......@@ -1121,5 +1121,12 @@ config DEVPORT
source "drivers/s390/char/Kconfig"
config RAMOOPS
tristate "Log panic/oops to a RAM buffer"
default n
This enables panic and oops messages to be logged to a circular
buffer in RAM where it can be read back at some later point.
......@@ -108,6 +108,7 @@ obj-$(CONFIG_HANGCHECK_TIMER) += hangcheck-timer.o
obj-$(CONFIG_TCG_TPM) += tpm/
obj-$(CONFIG_PS3_FLASH) += ps3flash.o
obj-$(CONFIG_RAMOOPS) += ramoops.o
obj-$(CONFIG_JS_RTC) += js-rtc.o
js-rtc-y = rtc.o
* RAM Oops/Panic logger
* Copyright (C) 2010 Marco Stornelli <>
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/kmsg_dump.h>
#include <linux/time.h>
#include <linux/io.h>
#include <linux/ioport.h>
#define RAMOOPS_KERNMSG_HDR "===="
#define RAMOOPS_HEADER_SIZE (5 + sizeof(struct timeval))
#define RECORD_SIZE 4096
static ulong mem_address;
module_param(mem_address, ulong, 0400);
"start of reserved RAM used to store oops/panic logs");
static ulong mem_size;
module_param(mem_size, ulong, 0400);
"size of reserved RAM used to store oops/panic logs");
static int dump_oops = 1;
module_param(dump_oops, int, 0600);
"set to 1 to dump oopses, 0 to only dump panics (default 1)");
static struct ramoops_context {
struct kmsg_dumper dump;
void *virt_addr;
phys_addr_t phys_addr;
unsigned long size;
int count;
int max_count;
} oops_cxt;
static void ramoops_do_dump(struct kmsg_dumper *dumper,
enum kmsg_dump_reason reason, const char *s1, unsigned long l1,
const char *s2, unsigned long l2)
struct ramoops_context *cxt = container_of(dumper,
struct ramoops_context, dump);
unsigned long s1_start, s2_start;
unsigned long l1_cpy, l2_cpy;
int res;
char *buf;
struct timeval timestamp;
/* Only dump oopses if dump_oops is set */
if (reason == KMSG_DUMP_OOPS && !dump_oops)
buf = (char *)(cxt->virt_addr + (cxt->count * RECORD_SIZE));
memset(buf, '\0', RECORD_SIZE);
res = sprintf(buf, "%s", RAMOOPS_KERNMSG_HDR);
buf += res;
res = sprintf(buf, "%lu.%lu\n", (long)timestamp.tv_sec, (long)timestamp.tv_usec);
buf += res;
l2_cpy = min(l2, (unsigned long)(RECORD_SIZE - RAMOOPS_HEADER_SIZE));
l1_cpy = min(l1, (unsigned long)(RECORD_SIZE - RAMOOPS_HEADER_SIZE) - l2_cpy);
s2_start = l2 - l2_cpy;
s1_start = l1 - l1_cpy;
memcpy(buf, s1 + s1_start, l1_cpy);
memcpy(buf + l1_cpy, s2 + s2_start, l2_cpy);
cxt->count = (cxt->count + 1) % cxt->max_count;
static int __init ramoops_init(void)
struct ramoops_context *cxt = &oops_cxt;
int err = -EINVAL;
if (!mem_size) {
printk(KERN_ERR "ramoops: invalid size specification");
goto fail3;
if (mem_size < RECORD_SIZE) {
printk(KERN_ERR "ramoops: size too small");
goto fail3;
cxt->max_count = mem_size / RECORD_SIZE;
cxt->count = 0;
cxt->size = mem_size;
cxt->phys_addr = mem_address;
if (!request_mem_region(cxt->phys_addr, cxt->size, "ramoops")) {
printk(KERN_ERR "ramoops: request mem region failed");
err = -EINVAL;
goto fail3;
cxt->virt_addr = ioremap(cxt->phys_addr, cxt->size);
if (!cxt->virt_addr) {
printk(KERN_ERR "ramoops: ioremap failed");
goto fail2;
cxt->dump.dump = ramoops_do_dump;
err = kmsg_dump_register(&cxt->dump);
if (err) {
printk(KERN_ERR "ramoops: registering kmsg dumper failed");
goto fail1;
return 0;
release_mem_region(cxt->phys_addr, cxt->size);
return err;
static void __exit ramoops_exit(void)
struct ramoops_context *cxt = &oops_cxt;
if (kmsg_dump_unregister(&cxt->dump) < 0)
printk(KERN_WARNING "ramoops: could not unregister kmsg_dumper");
release_mem_region(cxt->phys_addr, cxt->size);
MODULE_AUTHOR("Marco Stornelli <>");
MODULE_DESCRIPTION("RAM Oops/Panic logger/driver");
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