Undefined symbols __zig_probe_stack and others

[solar stirrup]

I'm making a kernel in zig but I'm getting those linker errors. Is there anything I can add to the build script to disable stack checking ? I'm currently building a static library.

I'm also getting undefined references for memset and memcpy despite setting the target to freestanding and link_libc to false

Can anyone please help me ? Thanks in advance !

I got it to stop by adding setRuntimeSafety to false in my function but I'd like to find a way to just have it happen without me needing to add it to every function

[cobalt dagger]

You can either bundle compiler_rt in the static lib

lib.bundle_compiler_rt = true;
lib.pie = true;

or set the .optimize = ReleaseSmall, for b.addStaticLibrary to disable safety checks

[solar stirrup]

What does compiler rt do exactly ?

[cobalt dagger]

it's runtime for safety checks and emulations for things that hardware don't support natively

[solar stirrup]

Would add interact ok with my freestanding target ? Suppose some check fails, won't it try to print something to the console ?

[cobalt dagger]

it will call panic

[solar stirrup]

So that's all I need to provide ?

[cobalt dagger]

yeah

[solar stirrup]

Alright thank you very much, I'll test all that once I get home

[cobalt dagger]

source for the compiler_rt is here btw if interested https://github.com/ziglang/zig/tree/d5db02728ce3ff3ba74a3e3f9050c3ea9ed34752/lib/compiler_rt

[solar stirrup]

I'm seeing it provides panic with a stack trace but I'm unsure of how it constructs it ?

My stack is currently set up a bit weird

I just have a big block of memory I set sp to before jumping into the kernel entry point which is a naked c function which then calls the main zig function with the sysv abi

I'm not sure how it'll try to build a stack trace from that

[cobalt dagger]

it doesn't https://github.com/ziglang/zig/blob/master/lib/std/builtin.zig#L48

[solar stirrup]

Ah so I can just ignore the stack trace parameter in panic ?

I see

[cobalt dagger]

yeah

[solar stirrup]

Neat ! Thank you

[cobalt dagger]

https://andrewkelley.me/post/zig-stack-traces-kernel-panic-bare-bones-os.html (older zig)

[solar stirrup]

Sorry I've only skimmed through all this, I'm still on my way home, but it seems like it's using debugging symbols and all that ? If so that'll be for way later I'm currently compiling my kernel into a flat binary and I'm pretty sure those symbols are stripped somewhere along the way

[cobalt dagger]

the zig std itself won't do anything for you (except giving useful utility functions), but that's showcasing approach to have stacktraces on baremetal in custom panic

also, the panic function is deprecated, it's going to be replaced by Panic namespace after 0.14

https://github.com/ziglang/zig/blob/master/lib/std/debug/FormattedPanic.zig example of such namespace

[solar stirrup]

I'm assuming I can't use it yet in 0.13 ?

[cobalt dagger]

Not sure, might not be in 0.13 indeed

can always pub const panic = Panic.call; in your main.zig to prepare for it though

[lime hemlock]

nah it's a 0.14 thing

[solar stirrup]

it's true I prolly should

[solar stirrup]

this worked btw

Thank you again !

[solar stirrup]

I do still have a question though : I tried triggering undefined behavior by writing into an array outside of its bounds but it just gave me a page fault instead of panicking

Is that normal ?

[cobalt dagger]

you are compiling with Debug or Safe mode right?

[solar stirrup]

I tried ReleaseSafe

[cobalt dagger]

can you show the code you tried to trigger panic with

[solar stirrup]

that's never 0

[cobalt dagger]

what is framebuffer_phys?

[solar stirrup]

physical address of the framebuffer, but I'm just using it because it's an external symbol that's never 0

[cobalt dagger]

I tried triggering undefined behavior by writing into an array outside of its bounds but it just gave me a page fault instead of panicking
I don't see any write here though

[solar stirrup]

I changed it to just use unreachable because it should be the same, still triggering a panic

[cobalt dagger]

Did you remove the @setRuntimeSafety(false) from your code?

[solar stirrup]

the old code was

var a = [_]i32{ 1, 2, 3 };
a[kinput.kinput.framebuffer_phys] = 123;

[solar stirrup]

Yes

oh wait

uh

maybe not in that specific function

:P

well now I feel stupid

thanks x)

[cobalt dagger]