Hey, I'm trying to write an OS in a mix between FASM/C and was wondering if there's a way I can call my C main function from my bootloader in FASM (I'm using ld to link everything and am using ELF .o output files).

Thanks!

-Ryan

so bootloader is in FASM. Bootloader should execute main() function of your kernel.

Where is your OS kernel stored? In what format? On what filesystem?

Piece of advice: don't call your kernel entry "main". Main is for C programs linked with libc, OS kernels generally don't (and shouldn't, imho) link against libc.

How do you call your entrypoint, though? Grab a copy of the ELF specs

Right now I'm not using a filesystem on it. I'm moreso focused on getting interrupts going before I worry about the HD. I want to compile everything to a flat binary right now. Now if I need to have a filesystem, I need to learn how to do filesystem programming (and if there are any good resources, please tell me if necessary right now).

Thanks, and my apologies if I make no sense, I have my obnoxious sister behind me.

Don't do a flat binary, using a proper file format (PE or ELF) for the kernel has a lot of advantages. And the difference in code for loading a raw kernel or a PE kernel is very small - I posted mine in some other topic.

f0dder - For this to happen, I would need a filesystem. Do you know a good filesystem I could use and some docs explaining it?

Nah, you don't necessarily need a filesystem, there's plenty of ways you can load your kernel:

*) etherboot with NBI format kernel - super fast load, and really great if you have a NIC with flash memory. I do (or did, considering how long it is since I worked on my kernel) this when testing with my dedicated testbox with an intel eepro100 card.

*) transfer across serial cable - slow. Did this before getting the eepro.

*) put the kernel on a (no-filesystem) floppy right after the bootsector and read in directly.

*) load your kernel from DOS (and use FAT filesystem or whatever). Feels somewhat "dirty", but means you can focus on writing your kernel, instead of getting it loaded .

*) iirc bochs has some "load kernel" hack mainly meant for linux, but which could be used for other stuff as well.

Cool, thanks.