Kernelnewbies Digest, Vol 107, Issue 9

Send Kernelnewbies mailing list submissions to
[email protected]

To subscribe or unsubscribe via the World Wide Web, visit
https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
or, via email, send a message with subject or body 'help' to
[email protected]

You can reach the person managing the list at
[email protected]

When replying, please edit your Subject line so it is more specific than "Re: Contents of Kernelnewbies digest..."

Today's Topics:

1. Re: Are there global constructors in the Linux kernel? (Konstantin Andreev)

----------------------------------------------------------------------

Message: 1
Date: Wed, 09 Oct 2019 11:54:26 +0300
From: Konstantin Andreev <[email protected]>
To: CRISTIAN ANDRES VARGAS GONZALEZ <[email protected]>,
[email protected]
Subject: Re: Are there global constructors in the Linux kernel?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=utf-8; format=flowed

Hi, Cristian. There are, a kinda of ...

kernel/taskstats.c:
| late_initcall(taskstats_init);

kernel/rcu/update.c:
| early_initcall(check_cpu_stall_init);

There is a whole set of macros STAGE_initcall() in include/linux/init.h

Arguments to these macros invokations are accounted and called by kernel initialization code at strictly defined stages of initialization. See
https://0xax.gitbooks.io/linux-insides/content/Concepts/linux-cpu-3.html

The only thing that is run before kernel is <a series of> platform-specific boot loaders, maybe under hypervisor control. Compiler has no power to insert something in between.

Regards, Konstantin.

CRISTIAN ANDRES VARGAS GONZALEZ, 09 Oct 2019 06:44 MSK:

Quoted 4 lines

Good day

I have been doing a little kernel following some repositories of

GitHub, videos and wikis, and I have found a topic that leaves me with doubts, the theme is the global constructors.

Quoted 2 lines

Suppose I write a program in c, for the user space, for my code to run I

must have the main function

Quoted 3 lines

int main() { /*Code*/}

The gcc compiler searches for this function to run my program, but

before that happens, I can use the global constructors and write a code that runs before the main function, but in the case of writing a kernel, why do I need to run lines of code before the kernel is executed ?, I understand that when writing a kernel there is no main function and that it is disabled to indicate it to the compiler. In the Linux kernel are there global constructors? If so, what things are executed before starting the kernel?

Quoted 1 line

att: cristian vargas.

------------------------------

Subject: Digest Footer

_______________________________________________
Kernelnewbies mailing list
[email protected]
https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

------------------------------

End of Kernelnewbies Digest, Vol 107, Issue 9
*********************************************