kopia lustrzana https://github.com/espressif/esp-idf
36 wiersze
1.4 KiB
Markdown
36 wiersze
1.4 KiB
Markdown
# Custom bootloader examples
|
|
|
|
The following directory contains two examples presenting the different ways
|
|
we provide in order to override the second stage bootloader or complete it
|
|
with few hooks.
|
|
|
|
## Extending the bootloader
|
|
|
|
In both cases, a project can define custom bootloader components by creating
|
|
them within a directory called `bootloader_components`.
|
|
|
|
Naming one of them `main` would let the compiler entirely override the
|
|
2nd stage bootloader with the implementation provided.
|
|
|
|
The bootloader components containing the hooks can have any name, as long
|
|
as it is part of `bootloader_components`, it will be taken into account
|
|
in the build.
|
|
|
|
## Hooks vs overriding the bootloader
|
|
|
|
In brief, using hooks will let the application add code to the bootloader.
|
|
They cannot replace the code that is already executed within bootloader.
|
|
|
|
Two hooks are available at the moment, the first one is called before the
|
|
initialization, and the second one is performed after the bootloader
|
|
initialization, before choosing and loading any partition. The
|
|
signature for these hooks can be found in `bootloader_hooks.h` file in
|
|
`components/bootloader/subproject/main/`.
|
|
|
|
|
|
On the other hand, overriding the bootloader offers the possibility to
|
|
totally or partially re-write it, in order to include, remove or modify
|
|
parts of it. Thanks to this, it will be fully customizable.
|
|
This shall only be used if heavy changes are required and they cannot
|
|
be done with hooks or within an application.
|