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POYet another 'undefined reference to _main'
 

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  1. POYet another 'undefined reference to _main'
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    <p>I've been attempting to convert the bulk of my current OS project from x86 Assembly over to C and assemble with NASM and compile with MinGW. When linking, I get these errors:</p> <pre><code>ld: warning: cannot find entry symbol start; defaulting to 00100000 o\main.o:main.c:(.text+0x7): undefined reference to `_main' </code></pre> <p>Here's the script I'm compilng, assembling and linking with:</p> <pre><code>gcc -c main.c -o o\main.o -fno-leading-underscore nasm boot.asm -o o\boot.o -fcoff ld -o bin\kernel.bin o\boot.o o\main.o -Tlink.ld </code></pre> <p>...and my linker script is the following:</p> <pre><code>ENTRY(start) SECTIONS { .text 0x100000 : { code = .; _code = .; __code = .; *(.text) . = ALIGN(4096); } .data : { data = .; _data = .; __data = .; *(.data) *(.rodata) . = ALIGN(4096); } .bss : { bss = .; _bss = .; __bss = .; *(.bss) . = ALIGN(4096); } end = .; _end = .; __end = .; } </code></pre> <p>When I use nm on main.o, it says that there is something with the symbol '__main', but I've declared it like this:</p> <pre><code>int main() { return 0xDEADBABA; } </code></pre> <p>Here's boot.asm:</p> <pre><code>MBOOT_PAGE_ALIGN equ 1&lt;&lt;0 ; Load kernel and modules on a page boundary MBOOT_MEM_INFO equ 1&lt;&lt;1 ; Provide your kernel with memory info MBOOT_HEADER_MAGIC equ 0x1BADB002 ; Multiboot Magic value MBOOT_HEADER_FLAGS equ MBOOT_PAGE_ALIGN | MBOOT_MEM_INFO MBOOT_CHECKSUM equ -(MBOOT_HEADER_MAGIC + MBOOT_HEADER_FLAGS) [bits 32] [global mboot] [extern code] [extern bss] [extern end] mboot: dd MBOOT_HEADER_MAGIC dd MBOOT_HEADER_FLAGS dd MBOOT_CHECKSUM dd mboot dd code dd bss dd end dd start [extern main] [global start] start: push ebx cli call main jmp $ </code></pre> <p>I suspect that this problem I'm having is because of Microsoft being their usual, stupid selves and requiring some sort of underscore prefix or something. Can anyone please provide a solution to this problem? Cheers.</p>
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    1. COShow us `boot.asm`.
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      1. POYet another 'undefined reference to _main'
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    2. COSure, just edited my question and added it
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      1. POYet another 'undefined reference to _main'
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    3. COHmm I bet Microsoft has it done just fine :D. What does the 'main' symbol look like if you dont use -fno-leading-underscore?
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      1. POYet another 'undefined reference to _main'
      1. USPyjong
 

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