Trouble compiling C code: error: expected '=', ',', ';', 'asm' or 'attribute' before 'int'

Question

I'm using James M tutorials on writing a kernel. I writing the code with a cross compiler for the elf-i386 arch on macOS 10.12 with GCC 6.2.0 and Binutils.

Everything compiles except main.c, which fails with this error:

Error: expected '=', ',', ';', 'asm' or '__attribute__' before 'int'.

However, the file is exactly as it is in the tutorial. Can anyone help me figure out why?

/*
Sierra Kernel
kernel.c -- Main kernel file
Copyright (C) 2017  Jacobo Soffer <[email protected]>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>. 
*/

#include <os.h>

int main(struct multiboot *mboot_ptr)
{
    kprint("Welcome to the Sierra Kernel! \n"); // Test VGA Driver
    kprint(BUILD_FULL); // Print version information
    asm volatile ("int $0x3");  // Test interrupts
    asm volatile ("int $0x4");
}

A public repo with all the kernel code is available at: https://gitlab.com/SierraKernel/Core/tree/master

It looks like you have an extra comma: int main(struct multiboot *mboot_ptr) — ad absurdum
Note that you'd need to think carefully about where the highly non-standard struct multiboot * argument to main() is going to come from. You must be working on an embedded system, but if you're writing the kernel, what is going to initialize and pass that structure to the kernel? — Jonathan Leffler

werber bang werber bang · Accepted Answer · 2017-01-24T14:35:33

May be it's a late answer , but generally the error is pointing to something not right in the file included just before int , in your case it's os.h ,try to spot if there are any missing ; in this file or any file that it includes.

Trouble compiling C code: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'int'

4 Answers

Trouble compiling C code: error: expected '=', ',', ';', 'asm' or 'attribute' before 'int'