1 Ramoops oops/panic logger
2 =========================
4 ramoops provides persistent RAM storage for oops and panics, so they can be
5 recovered after a reboot. This is a child-node of "/reserved-memory", and
6 is named "ramoops" after the backend, rather than "pstore" which is the
9 Parts of this storage may be set aside for other persistent log buffers, such
10 as kernel log messages, or for optional ECC error-correction data. The total
11 size of these optional buffers must fit in the reserved region.
13 Any remaining space will be used for a circular buffer of oops and panic
14 records. These records have a configurable size, with a size of 0 indicating
15 that they should be disabled.
17 At least one of "record-size", "console-size", "ftrace-size", or "pmsg-size"
18 must be set non-zero, but are otherwise optional as listed below.
23 - compatible: must be "ramoops"
25 - reg: region of memory that is preserved between reboots
30 - ecc-size: enables ECC support and specifies ECC buffer size in bytes
31 (defaults to 0: no ECC)
33 - record-size: maximum size in bytes of each kmsg dump.
34 (defaults to 0: disabled)
36 - console-size: size in bytes of log buffer reserved for kernel messages
37 (defaults to 0: disabled)
39 - ftrace-size: size in bytes of log buffer reserved for function tracing and
40 profiling (defaults to 0: disabled)
42 - pmsg-size: size in bytes of log buffer reserved for userspace messages
43 (defaults to 0: disabled)
45 - mem-type: if present, sets the type of mapping is to be used to map the
46 reserved region. mem-type: 0 = write-combined (default), 1 = unbuffered,
49 - unbuffered: deprecated, use mem_type instead. If present, and mem_type is
50 not specified, it is equivalent to mem_type = 1 and uses unbuffered mappings
51 to map the reserved region (defaults to buffered mappings mem_type = 0). If
52 both are specified -- "mem_type" overrides "unbuffered".
54 - max-reason: if present, sets maximum type of kmsg dump reasons to store
55 (defaults to 2: log Oopses and Panics). This can be set to INT_MAX to
56 store all kmsg dumps. See include/linux/kmsg_dump.h KMSG_DUMP_* for other
57 kmsg dump reason values. Setting this to 0 (KMSG_DUMP_UNDEF), means the
58 reason filtering will be controlled by the printk.always_kmsg_dump boot
59 param: if unset, it will be KMSG_DUMP_OOPS, otherwise KMSG_DUMP_MAX.
61 - no-dump-oops: deprecated, use max_reason instead. If present, and
62 max_reason is not specified, it is equivalent to max_reason = 1
65 - flags: if present, pass ramoops behavioral flags (defaults to 0,
66 see include/linux/pstore_ram.h RAMOOPS_FLAG_* for flag values).