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Griwes wrote:Note: `int` does not have the same size as `byte`.

benjii wrote:First three lines are printed in assembly code. The fourth line is printed in C code with my printf function.

Combuster wrote:

benjii wrote:First three lines are printed in assembly code. The fourth line is printed in C code with my printf function.

And I assume it's in that order? My crystal ball suggests your linking is off and it executes stray printf code before entering your bootstrap... Can you post the commands you use to compile, link and build your image? Include linker scripts if you have them.

----------ASM----------

nasm loader/booter/bootsector.asm -f bin -o bootsector
nasm loader/booter/stage2.asm -f bin -o stage2.bin
nasm loader/booter/idt.asm -f elf -o idt.o
 
----------C----------
 
gcc loader/booter/i386.c -c -m32 -nostdlib -nostartfiles -nodefaultlibs -I include -o i386.o
gcc loader/booter/pic.c -c -m32 -nostdlib -nostartfiles -nodefaultlibs -I include -o pic.o
gcc loader/booter/main.c -c -m32 -nostdlib -nostartfiles -nodefaultlibs -I include -o main.o
gcc clib/printf.c -c -m32 -nostdlib -nostartfiles -nodefaultlibs -I include -o printf.o
gcc clib/string.c -c -m32 -nostdlib -nostartfiles -nodefaultlibs -I include -o string.o
gcc clib/stdlib.c -c -m32 -nostdlib -nostartfiles -nodefaultlibs -I include -o stdlib.o
 
----------LD----------
 
ld printf.o stdlib.o string.o i386.o idt.o pic.o main.o -m elf_i386 -e main -T link.ld --strip-all -o stage2.elf

    ENTRY (main)
    SECTIONS {
        . = 0x100000;          
        .text : {
            *(.text)
        }
        .data : {
            *(.rodata)
            *(.rdata)
            *(.data)
        }
        .bss : {
            *(.bss)
        }
        /DISCARD/ : {
            *(.comment)
        }
    }

P.S. I tried adding magic breakpoint before calling printf function, but that damn space was already there...

Combuster wrote:1) I see a 64-bit Linux host and a lack of a crosscompiler... And especially since you're using "main" (special name!), there will probably be setup code added that you don't find in regular functions.

2) I also see an ELF-formatted kernel binary combined with a custom bootstrap, of which I'm guessing doesn't know what ELF is.

3) And there's that magic printf.o coming first on the command line, which often means it is also the first thing in the binary, and hence the first thing getting executed assuming I'm right about part 2.

4) The entry point is in C land. That means your second stage must be taking care of everything C need, including all segment registers and a valid ESP.

P.S. I tried adding magic breakpoint before calling printf function, but that damn space was already there...

Put your magic breakpoint just before leaving stage2, then go figure where it actually ends up, you'll probably be surprised

Combuster wrote:With that shortlist of features I'm guessing your problem is not on my list of things I'd have seen from a <10 post forum member before.

Since the obvious bugs are out of the way, are you comfortable with zipping the whole thing up so I can build it locally and see how it really behaves?

Combuster wrote:What address is that stack pointing to?

Combuster wrote:If you read that article properly, you'll see that 0x9FC00 isn't going to be a stable fix.

I'll go check if there's a buildscript when I get out of work and test the thing for myself. If not, I'll have to expire my offer because the rest of the week is going to be epically busy.