0001 # SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
0002 %YAML 1.2
0003 ---
0004 $id: "http://devicetree.org/schemas/reserved-memory/ramoops.yaml#"
0005 $schema: "http://devicetree.org/meta-schemas/core.yaml#"
0006
0007 title: Ramoops oops/panic logger
0008
0009 description: |
0010 ramoops provides persistent RAM storage for oops and panics, so they can be
0011 recovered after a reboot. This is a child-node of "/reserved-memory", and
0012 is named "ramoops" after the backend, rather than "pstore" which is the
0013 subsystem.
0014
0015 Parts of this storage may be set aside for other persistent log buffers, such
0016 as kernel log messages, or for optional ECC error-correction data. The total
0017 size of these optional buffers must fit in the reserved region.
0018
0019 Any remaining space will be used for a circular buffer of oops and panic
0020 records. These records have a configurable size, with a size of 0 indicating
0021 that they should be disabled.
0022
0023 At least one of "record-size", "console-size", "ftrace-size", or "pmsg-size"
0024 must be set non-zero, but are otherwise optional as listed below.
0025
0026 maintainers:
0027 - Kees Cook <keescook@chromium.org>
0028
0029 allOf:
0030 - $ref: "reserved-memory.yaml"
0031
0032 properties:
0033 compatible:
0034 const: ramoops
0035
0036 reg:
0037 description: region of memory that is preserved between reboots
0038
0039 ecc-size:
0040 $ref: /schemas/types.yaml#/definitions/uint32
0041 description: enables ECC support and specifies ECC buffer size in bytes
0042 default: 0 # no ECC
0043
0044 record-size:
0045 $ref: /schemas/types.yaml#/definitions/uint32
0046 description: maximum size in bytes of each kmsg dump
0047 default: 0
0048
0049 console-size:
0050 $ref: /schemas/types.yaml#/definitions/uint32
0051 description: size in bytes of log buffer reserved for kernel messages
0052 default: 0
0053
0054 ftrace-size:
0055 $ref: /schemas/types.yaml#/definitions/uint32
0056 description: size in bytes of log buffer reserved for function tracing and profiling
0057 default: 0
0058
0059 pmsg-size:
0060 $ref: /schemas/types.yaml#/definitions/uint32
0061 description: size in bytes of log buffer reserved for userspace messages
0062 default: 0
0063
0064 mem-type:
0065 $ref: /schemas/types.yaml#/definitions/uint32
0066 description: if present, sets the type of mapping is to be used to map the reserved region.
0067 default: 0
0068 oneOf:
0069 - const: 0
0070 description: write-combined
0071 - const: 1
0072 description: unbuffered
0073 - const: 2
0074 description: cached
0075
0076 max-reason:
0077 $ref: /schemas/types.yaml#/definitions/uint32
0078 default: 2 # log oopses and panics
0079 maximum: 0x7fffffff
0080 description: |
0081 If present, sets maximum type of kmsg dump reasons to store.
0082 This can be set to INT_MAX to store all kmsg dumps.
0083 See include/linux/kmsg_dump.h KMSG_DUMP_* for other kmsg dump reason values.
0084 Setting this to 0 (KMSG_DUMP_UNDEF), means the reason filtering will be
0085 controlled by the printk.always_kmsg_dump boot param.
0086 If unset, it will be 2 (KMSG_DUMP_OOPS), otherwise 5 (KMSG_DUMP_MAX).
0087
0088 flags:
0089 $ref: /schemas/types.yaml#/definitions/uint32
0090 default: 0
0091 description: |
0092 If present, pass ramoops behavioral flags
0093 (see include/linux/pstore_ram.h RAMOOPS_FLAG_* for flag values).
0094
0095 no-dump-oops:
0096 deprecated: true
0097 type: boolean
0098 description: |
0099 Use max_reason instead. If present, and max_reason is not specified,
0100 it is equivalent to max_reason = 1 (KMSG_DUMP_PANIC).
0101
0102 unbuffered:
0103 deprecated: true
0104 type: boolean
0105 description: |
0106 Use mem_type instead. If present, and mem_type is not specified,
0107 it is equivalent to mem_type = 1 and uses unbuffered mappings to map
0108 the reserved region (defaults to buffered mappings mem_type = 0).
0109 If both are specified -- "mem_type" overrides "unbuffered".
0110
0111 unevaluatedProperties: false
0112
0113 required:
0114 - compatible
0115 - reg
0116
0117 anyOf:
0118 - required: [record-size]
0119 - required: [console-size]
0120 - required: [ftrace-size]
0121 - required: [pmsg-size]
0122
0123 examples:
0124 - |
0125 / {
0126 compatible = "foo";
0127 model = "foo";
0128 #address-cells = <1>;
0129 #size-cells = <1>;
0130
0131 reserved-memory {
0132 #address-cells = <1>;
0133 #size-cells = <1>;
0134 ranges;
0135
0136 ramoops@bfdf0000 {
0137 compatible = "ramoops";
0138 reg = <0xbfdf0000 0x10000>; /* 64kB */
0139 console-size = <0x8000>; /* 32kB */
0140 record-size = <0x400>; /* 1kB */
0141 ecc-size = <16>;
0142 };
0143 };
0144 };
