This make the process of applying overlays more reliable by:
1. Ignoring dtb files that are not really device trees. [^1]
2. Adding a `filter` option (per-overlay, there already is a global one)
to limit the files to which the overlay applies. This is useful
in cases where the `compatible` string is ambiguous and multiple
unrelated files match.
Previously the script would fail in both cases.
[^1]: For example, there is dtbs/overlays/overlay_map.dtb in the
Raspberry Pi 1 kernel.
the conversion procedure is simple:
- find all things that look like options, ie calls to either `mkOption`
or `lib.mkOption` that take an attrset. remember the attrset as the
option
- for all options, find a `description` attribute who's value is not a
call to `mdDoc` or `lib.mdDoc`
- textually convert the entire value of the attribute to MD with a few
simple regexes (the set from mdize-module.sh)
- if the change produced a change in the manual output, discard
- if the change kept the manual unchanged, add some text to the
description to make sure we've actually found an option. if the
manual changes this time, keep the converted description
this procedure converts 80% of nixos options to markdown. around 2000
options remain to be inspected, but most of those fail the "does not
change the manual output check": currently the MD conversion process
does not faithfully convert docbook tags like <code> and <package>, so
any option using such tags will not be converted at all.
Run the device tree overlays through the preprocessor before compiling it, as
is done in the kernel. This helps make overlays easier to understand, and
improves compatibility with those found in the wild.
I found the correct command line by running the kernel build with V=1, and then
removing all the arguments related to dependency tracking.
Since dtc 1.4.7 (released in 2018), there has been a much nicer syntax for
device tree overlays. This commit converts the dtsText example to use this
syntax.
The `platform` field is pointless nesting: it's just stuff that happens
to be defined together, and that should be an implementation detail.
This instead makes `linux-kernel` and `gcc` top level fields in platform
configs. They join `rustc` there [all are optional], which was put there
and not in `platform` in anticipation of a change like this.
`linux-kernel.arch` in particular also becomes `linuxArch`, to match the
other `*Arch`es.
The next step after is this to combine the *specific* machines from
`lib.systems.platforms` with `lib.systems.examples`, keeping just the
"multiplatform" ones for defaulting.
Now allows applying external overlays either in form of
.dts file, literal dts context added to store or precompiled .dtbo.
If overlays are defined, kernel device-trees are compiled with '-@'
so the .dtb files contain symbols which we can reference in our
overlays.
Since `fdtoverlay` doesn't respect `/ compatible` by itself
we query compatible strings of both `dtb` and `dtbo(verlay)`
and apply only if latter is substring of the former.
Also adds support for filtering .dtb files (as there are now nearly 1k
dtbs).
Co-authored-by: georgewhewell <georgerw@gmail.com>
Co-authored-by: Kai Wohlfahrt <kai.wohlfahrt@gmail.com>
This can be used to explicitly specify a specific dtb file, relative to
the dtb base.
Update the generic-extlinux-compatible module to make use of this option.
Add support for custom device-tree files, and applying overlays to them.
This is useful for supporting non-discoverable hardware, such as sensors
attached to GPIO pins on a Raspberry Pi.
