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concepts/initcalls: add module_init macro information

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While reading about initcalls around the web and kernel source code I found
that the information of what happens to __init functions not explicitly set to
any initcall list pretty useful. With this patch such information is added.

Signed-off-by: Bruno Meneguele <bmeneguele@gmail.com>
This commit is contained in:
Bruno Meneguele 2020-02-21 17:03:12 -03:00
parent cbc004adde
commit cdbc603fbd
1 changed files with 14 additions and 0 deletions
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Concepts/linux-cpu-3.md
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@ -381,6 +381,20 @@ Besides the `rootfs_initcall` level, there are additional `console_initcall`, `s
The main goal of these additional levels is to wait for completion of all modules related initialization routines for a certain level.
Another point worthy of mention is the `module_init(x)` macro, defined at [include/linux/module.h](https://github.com/torvalds/linux/blob/16f73eb02d7e1765ccab3d2018e0bd98eb93d973/include/linux/module.h) as:
```C
#define module_init(x) __initcall(x);
```
If we follow and check what's the definition of `__initcall(x)` at [include/linux/init.h](https://github.com/torvalds/linux/blob/16f73eb02d7e1765ccab3d2018e0bd98eb93d973/include/linux/init.h) we can see that it's being set as an `device_initcall`:
```C
#define __initcall(fn) device_initcall(fn)
```
With that we can conclude that when a function set as `__init` of certain module isn't explicitly added to a specific initcall category, but using `module_init()` macro, it is added to device initcall list by default.
That's all.
Conclusion