Making a Stand Alone Binary [OS] - The LearnixOS Book

[giscus[bot]]

ch01-01-making-stand-alone-binary

https://www.learnix-os.com/ch01-01-making-stand-alone-binary.html

[Zhomart]

Trying to build this on macos with rustc (1.92.0), I see this error:

❯ cargo build
   Compiling os1 v0.1.0 (/Users/user/Work/learnix-os/os1)
error: linking with `cc` failed: exit status: 1
  |
  = note:  "cc" "/var/folders/gf/4651d3x97j18dln7551m6z080000gn/T/rustccH6TIW/symbols.o" "<2 object files omitted>" "<sysroot>/lib/rustlib/aarch64-apple-darwin/lib/{libcore-*,libcompiler_builtins-*}.rlib" "-arch" "arm64" "-mmacosx-version-min=11.0.0" "-o" "/Users/user/Work/learnix-os/os1/target/debug/deps/os1-25407a216bf9bd26" "-Wl,-dead_strip" "-nodefaultlibs" "--script=/Users/user/Work/learnix-os/os1/linker.ld"
  = note: some arguments are omitted. use `--verbose` to show all linker arguments
  = note: clang: error: unknown argument: '--script=/Users/user/Work/learnix-os/os1/linker.ld'

error: could not compile `os1` (bin "os1") due to 1 previous error

what are the prerequisites for this to work?

[joelpeapen]

you need to change --script={} to -T={}. --script doesn't look like a valid flag for cc.

[sagi21805]

Hi, thanks for pointing that out. The initial version was build on my own windows machine in which I didn't had this problem.

The problem is that the argument for adding a script for Mac is different.

In the next chapter we define a custom build target which uses rust default linker, and thus avoids this problem in all platforms.

Also, I might have forgotten to mention that this uses nightly.

The general solution:

Take the 16bit target (Can be also the 32bit or 64 bit one) from the next chapter, and put it in a file custom-target.json

Then use the following command to run:

cargo +nightly build --target custom-target.json -Zbuild-std=core

I will add this to the current chapter, thank for the comment

[sagi21805]

Hopefully fixed in #23

[Zhomart]

thanks!

Btw, this needs to be fixed as well:

Note: Build targets will be discussed in more detail in the next chapter. You might have to install the target with rustup add target x86_64-unknown-none

to: rustup target add x86_64-unknown-none

[michuhu]

This build.rs solves the problem for macOS with ARM.
btw, don't forget to rustup target add aarch64-apple-darwin

fn main() {
    // Tell the linker to not use standard startup files
    println!("cargo:rustc-link-arg=-nostartfiles");
    
    // Set the entry point
    println!("cargo:rustc-link-arg=-e");
    println!("cargo:rustc-link-arg=_main");
    
    // Make it static
    println!("cargo:rustc-link-arg=-static");
}

[liamdiprose]

Who is the target audience? I think these topics are more interesting after people have experienced blinking led. Why do people come to programmable devices? Control, automation, compression.

[sagi21805]

I wanted the target audience to be people who want to engage with the topic, and might be even new to low level programming, this book aims to explain almost everything about how to create a working bootable OS without hiding any details

[liamdiprose]

My mistake - This section is very similar to an embedded devices course though!

I've been hired to teach a bunch of engineers how to program embedded devices with Rust, While I believe the connection between the virtual and physical needs to be made as soon as possible, I'll definitely direct them here if they reject my boilerplate :)

[superboum]

Thanks a lot for this project: I want to run code on computer since a long time and your approach seems easy enough that I felt confident enough to finally try for the first time.

A minor comment: your linker script is called linker_script.ld but, just below, it is called with linker.ld.
So you will have the following error:

  = note: rust-lld: error: cannot open <redacted>/learnix/linker.ld: No such file or directory

[sagi21805]

Thanks, will fix!

[sagi21805]

fixed in #23