Nim's syntax looks like it would be great for writing a toy x86 kernel after the initial hurdles. I wrote a simple file, kernel.nim:
proc kmain {.exportc.} = discard
nim cc --cc:clang --cpu:i386 --noLinking:on --nimcache:"." --passC:"-m32 -ffreestanding -fno-stack-protector" --os:standalone --noMain:on kernel.nim
proc rawoutput(s: string) = discard
proc panic(s: string) = discard
But then when I link it, like this:
ld -m elf_i386 -T linker.ld -o kernel boot.o @mkernel.nim.c.o
ld: @mkernel.nim.c.o: in function `PreMain':
@mkernel.nim.c:(.text+0xa2): undefined reference to `systemInit000'
ld: kernel: hidden symbol `systemInit000' isn't defined
Here's the reference to that in the generated source code:
void PreMainInner() {
systemInit000();
testDatInit000();
}
void PreMain() {
void (*volatile inner)();
systemDatInit000();
inner = PreMainInner;
initStackBottomWith((void *)&inner);
(*inner)();
}
I also had to install lib32-glibc on my Arch system to get it to compile (it needed the gnu/stubs-32.h header) despite not linking libc, curious why.
Any help is appreciated!
This command:
nim cc --cc:clang --cpu:i386 --noLinking:on --nimcache:"." --passC:"-m32 -ffreestanding -fno-stack-protector" --os:any -d:useMalloc -d:StandAloneHeap=1047856 --noMain:on kernel.nim
You may need to choose useMalloc or standAloneHeap. Also, I'd set --gc:arc (though orc should be fine too).
The value in -d:StandAloneHeap=1047856 is a bit over 1megabyte. It's was just a simple array based memory heap that's setup in the executable.
I encounter the same issue not using malloc but using standAloneHeap (with or without arc):
nim cc --cc:clang --cpu:i386 --noLinking:on --nimcache:"." --passC:"-m32 -ffreestanding -fno-stack-protector" --os:any -d:StandAloneHeap=1047856 --gc:arc --noMain:on kernel.nim
I see, so it's just a temporary fixed buffer. That's quite handy