ramoops.yaml

  1# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
  2%YAML 1.2
  3---
  4$id: http://devicetree.org/schemas/reserved-memory/ramoops.yaml#
  5$schema: http://devicetree.org/meta-schemas/core.yaml#
  6
  7title: Ramoops oops/panic logger
  8
  9description: |
 10  ramoops provides persistent RAM storage for oops and panics, so they can be
 11  recovered after a reboot. This is a child-node of "/reserved-memory", and
 12  is named "ramoops" after the backend, rather than "pstore" which is the
 13  subsystem.
 14
 15  Parts of this storage may be set aside for other persistent log buffers, such
 16  as kernel log messages, or for optional ECC error-correction data.  The total
 17  size of these optional buffers must fit in the reserved region.
 18
 19  Any remaining space will be used for a circular buffer of oops and panic
 20  records.  These records have a configurable size, with a size of 0 indicating
 21  that they should be disabled.
 22
 23  At least one of "record-size", "console-size", "ftrace-size", or "pmsg-size"
 24  must be set non-zero, but are otherwise optional as listed below.
 25
 26maintainers:
 27  - Kees Cook <keescook@chromium.org>
 28
 29allOf:
 30  - $ref: reserved-memory.yaml
 31
 32properties:
 33  compatible:
 34    const: ramoops
 35
 36  reg:
 37    description: region of memory that is preserved between reboots
 38
 39  ecc-size:
 40    $ref: /schemas/types.yaml#/definitions/uint32
 41    description: enables ECC support and specifies ECC buffer size in bytes
 42    default: 0 # no ECC
 43
 44  record-size:
 45    $ref: /schemas/types.yaml#/definitions/uint32
 46    description: maximum size in bytes of each kmsg dump
 47    default: 0
 48
 49  console-size:
 50    $ref: /schemas/types.yaml#/definitions/uint32
 51    description: size in bytes of log buffer reserved for kernel messages
 52    default: 0
 53
 54  ftrace-size:
 55    $ref: /schemas/types.yaml#/definitions/uint32
 56    description: size in bytes of log buffer reserved for function tracing and profiling
 57    default: 0
 58
 59  pmsg-size:
 60    $ref: /schemas/types.yaml#/definitions/uint32
 61    description: size in bytes of log buffer reserved for userspace messages
 62    default: 0
 63
 64  mem-type:
 65    $ref: /schemas/types.yaml#/definitions/uint32
 66    description: if present, sets the type of mapping is to be used to map the reserved region.
 67    default: 0
 68    oneOf:
 69      - const: 0
 70        description: write-combined
 71      - const: 1
 72        description: unbuffered
 73      - const: 2
 74        description: cached
 75
 76  max-reason:
 77    $ref: /schemas/types.yaml#/definitions/uint32
 78    default: 2 # log oopses and panics
 79    maximum: 0x7fffffff
 80    description: |
 81      If present, sets maximum type of kmsg dump reasons to store.
 82      This can be set to INT_MAX to store all kmsg dumps.
 83      See include/linux/kmsg_dump.h KMSG_DUMP_* for other kmsg dump reason values.
 84      Setting this to 0 (KMSG_DUMP_UNDEF), means the reason filtering will be
 85      controlled by the printk.always_kmsg_dump boot param.
 86      If unset, it will be 2 (KMSG_DUMP_OOPS), otherwise 5 (KMSG_DUMP_MAX).
 87
 88  flags:
 89    $ref: /schemas/types.yaml#/definitions/uint32
 90    default: 0
 91    description: |
 92      If present, pass ramoops behavioral flags
 93      (see include/linux/pstore_ram.h RAMOOPS_FLAG_* for flag values).
 94
 95  no-dump-oops:
 96    deprecated: true
 97    type: boolean
 98    description: |
 99      Use max_reason instead. If present, and max_reason is not specified,
100      it is equivalent to max_reason = 1 (KMSG_DUMP_PANIC).
101
102  unbuffered:
103    deprecated: true
104    type: boolean
105    description: |
106      Use mem_type instead. If present, and mem_type is not specified,
107      it is equivalent to mem_type = 1 and uses unbuffered mappings to map
108      the reserved region (defaults to buffered mappings mem_type = 0).
109      If both are specified -- "mem_type" overrides "unbuffered".
110
111unevaluatedProperties: false
112
113required:
114  - compatible
115  - reg
116
117anyOf:
118  - required: [record-size]
119  - required: [console-size]
120  - required: [ftrace-size]
121  - required: [pmsg-size]
122
123examples:
124  - |
125    / {
126        compatible = "foo";
127        model = "foo";
128        #address-cells = <1>;
129        #size-cells = <1>;
130
131        reserved-memory {
132            #address-cells = <1>;
133            #size-cells = <1>;
134            ranges;
135
136            ramoops@bfdf0000 {
137                compatible = "ramoops";
138                reg = <0xbfdf0000 0x10000>; /* 64kB */
139                console-size = <0x8000>;    /* 32kB */
140                record-size = <0x400>;      /*  1kB */
141                ecc-size = <16>;
142            };
143        };
144    };