https://github.com/smartrent/ramoops_logger

Elixir Logger Backend that writes to the Linux Ramoops driver
https://github.com/smartrent/ramoops_logger

elixir elixir-logger linux

Last synced: 2 months ago
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Elixir Logger Backend that writes to the Linux Ramoops driver

• Host: GitHub
• URL: https://github.com/smartrent/ramoops_logger
• Owner: smartrent
• License: apache-2.0
• Created: 2019-02-01T16:51:04.000Z (almost 6 years ago)
• Default Branch: main
• Last Pushed: 2023-04-11T00:05:43.000Z (over 1 year ago)
• Last Synced: 2024-09-28T17:20:52.814Z (3 months ago)
• Topics: elixir, elixir-logger, linux
• Language: Elixir
• Homepage:
• Size: 59.6 KB
• Stars: 11
• Watchers: 11
• Forks: 2
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

        
# RamoopsLogger

[![CircleCI](https://circleci.com/gh/smartrent/ramoops_logger/tree/main.svg?style=svg)](https://circleci.com/gh/smartrent/ramoops_logger/tree/main)

[![Hex version](https://img.shields.io/hexpm/v/ramoops_logger.svg "Hex version")](https://hex.pm/packages/ramoops_logger)

This is an Elixir Logger backend for forwarding log messages to the [ramoops

logger](https://www.kernel.org/doc/html/v4.19/admin-guide/ramoops.html) on Linux

and Nerves systems. Messages sent to this log are written to a special area of

DRAM that can be recovered after reboots or very short power outages.

Here's a demo video:

[![RamoopsLogger Demo](http://img.youtube.com/vi/vpD511Bk5rU/0.jpg)](http://www.youtube.com/watch?v=vpD511Bk5rU)

## Configuration

RamoopsLogger uses the Linux `pstore` device driver, so it only works on

Linux-based platforms. Most official Nerves Projects systems start the `pstore`

driver automatically and you can skip the Linux configuration.

### Linux configuration

The most important part of using the RamoopsLogger is ensuring that the `pstore`

device driver is enabled and configured in your Linux kernel. The device driver

writes logs to a fixed location in DRAM that is platform-specific. If you are

lucky, someone will have determined a good place to store the logs. The official

Nerves Project systems all have a small amount of memory allocated for use by

the `pstore` driver. If you are not using Nerves, it's possible that one of the

device tree files (for ARM platforms) may be helpful.

If you're not using an official Nerves system, here's an example device tree

fragment that would need to be updated for your device, but may be helpful as a

start.

```c

reserved-memory {

        #address-cells = <1>;

        #size-cells = <1>;

        ranges;

        ramoops@88d00000{

                compatible = "ramoops";

                reg = <0x88d00000 0x100000>;

                ecc-size = <16>;

                record-size     = <0x00020000>;

                console-size    = <0x00020000>;

                ftrace-size     = <0>;

                pmsg-size       = <0x00020000>;

        };

};

```

One way of testing whether the `pstore` driver is available is to check whether

the `/dev/pmsg0` file exists.

### Update your Elixir project

Once you're satisfied with the Linux, add `ramoops_logger` to your project's

`mix.exs` dependencies list.

```elixir

def deps do

  [

    {:ramoops_logger, "~> 0.3.0"}

  ]

end

```

Next, update your `config.exs` to tell the Elixir Logger to send log messages to

the `RamoopsLogger`:

```elixir

use Mix.Config

# Add the RamoopsLogger backend. If you already have a logger configuration, to add

# RamoopsLogger the only change needed is to add RamoopsLogger to the :backends list.

config :logger, backends: [RamoopsLogger, :console]

```

## IEx Session Usage

To read the last ramoops log to the console run:

```elixir

iex> RamoopsLogger.dump()

```

To read the last ramoops log and it to a variable run:

```elixir

iex> {:ok, contents} = RamoopsLogger.read()

```

## Nerves Automatic Log Check

If you want to have your system check if there is an oops log available, and you

are using Nerves, you can add this to your `rootfs_overlay/etc/iex.exs` file in

your firmware project:

```elixir

if RamoopsLogger.available_log?() do

  IO.puts("Oops! There's something in the oops log. Check with RamoopsLogger.dump()")

end

```

## License

Copyright (C) 2020-21 SmartRent

    Licensed under the Apache License, Version 2.0 (the "License");

    you may not use this file except in compliance with the License.

    You may obtain a copy of the License at [http://www.apache.org/licenses/LICENSE-2.0](http://www.apache.org/licenses/LICENSE-2.0)

    Unless required by applicable law or agreed to in writing, software

    distributed under the License is distributed on an "AS IS" BASIS,

    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

    See the License for the specific language governing permissions and

    limitations under the License.