Build upon the limine Rust template and a working pipeline, display an orange background on load.

kernel/.gitignore

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+/kernel
+/target

kernel/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "bitflags"
+version = "2.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b8e56985ec62d17e9c1001dc89c88ecd7dc08e47eba5ec7c29c7b5eeecde967"
+
+[[package]]
+name = "limine"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "af6d2ee42712e7bd2c787365cd1dab06ef59a61becbf87bec7b32b970bd2594b"
+dependencies = [
+ "bitflags",
+]
+
+[[package]]
+name = "limine-rust-template"
+version = "0.1.0"
+dependencies = [
+ "limine",
+]

kernel/Cargo.toml

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+[package]
+name = "limine-rust-template"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+limine = "0.5"

kernel/GNUmakefile

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+# Nuke built-in rules and variables.
+MAKEFLAGS += -rR
+.SUFFIXES:
+
+# This is the name that our final executable will have.
+# Change as needed.
+override OUTPUT := kernel
+
+# Convenience macro to reliably declare user overridable variables.
+override USER_VARIABLE = $(if $(filter $(origin $(1)),default undefined),$(eval override $(1) := $(2)))
+
+# Target architecture to build for. Default to x86_64.
+$(call USER_VARIABLE,KARCH,x86_64)
+
+ifeq ($(RUST_TARGET),)
+    override RUST_TARGET := $(KARCH)-unknown-none
+	ifeq ($(KARCH),riscv64)
+    	override RUST_TARGET := riscv64gc-unknown-none-elf
+	endif
+endif
+
+ifeq ($(RUST_PROFILE),)
+    override RUST_PROFILE := dev
+endif
+
+override RUST_PROFILE_SUBDIR := $(RUST_PROFILE)
+ifeq ($(RUST_PROFILE),dev)
+    override RUST_PROFILE_SUBDIR := debug
+endif
+
+# Default target.
+.PHONY: all
+all:
+	RUSTFLAGS="-C relocation-model=static" cargo build --target $(RUST_TARGET) --profile $(RUST_PROFILE)
+	cp target/$(RUST_TARGET)/$(RUST_PROFILE_SUBDIR)/$$(cd target/$(RUST_TARGET)/$(RUST_PROFILE_SUBDIR) && find -maxdepth 1 -perm -111 -type f) kernel
+
+# Remove object files and the final executable.
+.PHONY: clean
+clean:
+	cargo clean
+	rm -rf kernel
+
+.PHONY: distclean
+distclean: clean

kernel/build.rs

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+fn main() {
+    let arch = std::env::var("CARGO_CFG_TARGET_ARCH").unwrap();
+    // Tell cargo to pass the linker script to the linker..
+    println!("cargo:rustc-link-arg=-Tlinker-{arch}.ld");
+    // ..and to re-run if it changes.
+    println!("cargo:rerun-if-changed=linker-{arch}.ld");
+}

kernel/linker-aarch64.ld

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+/* Tell the linker that we want an aarch64 ELF64 output file */
+OUTPUT_FORMAT(elf64-littleaarch64)
+
+/* We want the symbol kmain to be our entry point */
+ENTRY(kmain)
+
+/* Define the program headers we want so the bootloader gives us the right */
+/* MMU permissions; this also allows us to exert more control over the linking */
+/* process. */
+PHDRS
+{
+    text    PT_LOAD;
+    rodata  PT_LOAD;
+    data    PT_LOAD;
+}
+
+SECTIONS
+{
+    /* We want to be placed in the topmost 2GiB of the address space, for optimisations */
+    /* and because that is what the Limine spec mandates. */
+    /* Any address in this region will do, but often 0xffffffff80000000 is chosen as */
+    /* that is the beginning of the region. */
+    . = 0xffffffff80000000;
+
+    .text : {
+        *(.text .text.*)
+    } :text
+
+    /* Move to the next memory page for .rodata */
+    . = ALIGN(CONSTANT(MAXPAGESIZE));
+
+    .rodata : {
+        *(.rodata .rodata.*)
+    } :rodata
+
+    /* Move to the next memory page for .data */
+    . = ALIGN(CONSTANT(MAXPAGESIZE));
+
+    .data : {
+        *(.data .data.*)
+
+        /* Place the sections that contain the Limine requests as part of the .data */
+        /* output section. */
+        KEEP(*(.requests_start_marker))
+        KEEP(*(.requests))
+        KEEP(*(.requests_end_marker))
+    } :data
+
+    /* NOTE: .bss needs to be the last thing mapped to :data, otherwise lots of */
+    /* unnecessary zeros will be written to the binary. */
+    /* If you need, for example, .init_array and .fini_array, those should be placed */
+    /* above this. */
+    .bss : {
+        *(.bss .bss.*)
+        *(COMMON)
+    } :data
+
+    /* Discard .note.* and .eh_frame* since they may cause issues on some hosts. */
+    /DISCARD/ : {
+        *(.eh_frame*)
+        *(.note .note.*)
+    }
+}

kernel/linker-loongarch64.ld

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+/* Tell the linker that we want a loongarch64 ELF64 output file */
+OUTPUT_FORMAT(elf64-loongarch)
+
+/* We want the symbol kmain to be our entry point */
+ENTRY(kmain)
+
+/* Define the program headers we want so the bootloader gives us the right */
+/* MMU permissions; this also allows us to exert more control over the linking */
+/* process. */
+PHDRS
+{
+    text    PT_LOAD;
+    rodata  PT_LOAD;
+    data    PT_LOAD;
+}
+
+SECTIONS
+{
+    /* We want to be placed in the topmost 2GiB of the address space, for optimisations */
+    /* and because that is what the Limine spec mandates. */
+    /* Any address in this region will do, but often 0xffffffff80000000 is chosen as */
+    /* that is the beginning of the region. */
+    . = 0xffffffff80000000;
+
+    .text : {
+        *(.text .text.*)
+    } :text
+
+    /* Move to the next memory page for .rodata */
+    . = ALIGN(CONSTANT(MAXPAGESIZE));
+
+    .rodata : {
+        *(.rodata .rodata.*)
+    } :rodata
+
+    /* Move to the next memory page for .data */
+    . = ALIGN(CONSTANT(MAXPAGESIZE));
+
+    .data : {
+        *(.data .data.*)
+
+        /* Place the sections that contain the Limine requests as part of the .data */
+        /* output section. */
+        KEEP(*(.requests_start_marker))
+        KEEP(*(.requests))
+        KEEP(*(.requests_end_marker))
+    } :data
+
+    /* NOTE: .bss needs to be the last thing mapped to :data, otherwise lots of */
+    /* unnecessary zeros will be written to the binary. */
+    /* If you need, for example, .init_array and .fini_array, those should be placed */
+    /* above this. */
+    .bss : {
+        *(.bss .bss.*)
+        *(COMMON)
+    } :data
+
+    /* Discard .note.* and .eh_frame* since they may cause issues on some hosts. */
+    /DISCARD/ : {
+        *(.eh_frame*)
+        *(.note .note.*)
+    }
+}

kernel/linker-riscv64.ld

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+/* Tell the linker that we want a riscv64 ELF64 output file */
+OUTPUT_FORMAT(elf64-littleriscv)
+
+/* We want the symbol kmain to be our entry point */
+ENTRY(kmain)
+
+/* Define the program headers we want so the bootloader gives us the right */
+/* MMU permissions; this also allows us to exert more control over the linking */
+/* process. */
+PHDRS
+{
+    text    PT_LOAD;
+    rodata  PT_LOAD;
+    data    PT_LOAD;
+}
+
+SECTIONS
+{
+    /* We want to be placed in the topmost 2GiB of the address space, for optimisations */
+    /* and because that is what the Limine spec mandates. */
+    /* Any address in this region will do, but often 0xffffffff80000000 is chosen as */
+    /* that is the beginning of the region. */
+    . = 0xffffffff80000000;
+
+    .text : {
+        *(.text .text.*)
+    } :text
+
+    /* Move to the next memory page for .rodata */
+    . = ALIGN(CONSTANT(MAXPAGESIZE));
+
+    .rodata : {
+        *(.rodata .rodata.*)
+    } :rodata
+
+    /* Move to the next memory page for .data */
+    . = ALIGN(CONSTANT(MAXPAGESIZE));
+
+    .data : {
+        *(.data .data.*)
+
+        /* Place the sections that contain the Limine requests as part of the .data */
+        /* output section. */
+        KEEP(*(.requests_start_marker))
+        KEEP(*(.requests))
+        KEEP(*(.requests_end_marker))
+
+        *(.sdata .sdata.*)
+    } :data
+
+    /* NOTE: .bss needs to be the last thing mapped to :data, otherwise lots of */
+    /* unnecessary zeros will be written to the binary. */
+    /* If you need, for example, .init_array and .fini_array, those should be placed */
+    /* above this. */
+    .bss : {
+        *(.sbss .sbss.*)
+        *(.bss .bss.*)
+        *(COMMON)
+    } :data
+
+    /* Discard .note.* and .eh_frame* since they may cause issues on some hosts. */
+    /DISCARD/ : {
+        *(.eh_frame*)
+        *(.note .note.*)
+    }
+}

kernel/linker-x86_64.ld

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+/* Tell the linker that we want an x86_64 ELF64 output file */
+OUTPUT_FORMAT(elf64-x86-64)
+
+/* We want the symbol kmain to be our entry point */
+ENTRY(kmain)
+
+/* Define the program headers we want so the bootloader gives us the right */
+/* MMU permissions; this also allows us to exert more control over the linking */
+/* process. */
+PHDRS
+{
+    text    PT_LOAD;
+    rodata  PT_LOAD;
+    data    PT_LOAD;
+}
+
+SECTIONS
+{
+    /* We want to be placed in the topmost 2GiB of the address space, for optimisations */
+    /* and because that is what the Limine spec mandates. */
+    /* Any address in this region will do, but often 0xffffffff80000000 is chosen as */
+    /* that is the beginning of the region. */
+    . = 0xffffffff80000000;
+
+    .text : {
+        *(.text .text.*)
+    } :text
+
+    /* Move to the next memory page for .rodata */
+    . = ALIGN(CONSTANT(MAXPAGESIZE));
+
+    .rodata : {
+        *(.rodata .rodata.*)
+    } :rodata
+
+    /* Move to the next memory page for .data */
+    . = ALIGN(CONSTANT(MAXPAGESIZE));
+
+    .data : {
+        *(.data .data.*)
+
+        /* Place the sections that contain the Limine requests as part of the .data */
+        /* output section. */
+        KEEP(*(.requests_start_marker))
+        KEEP(*(.requests))
+        KEEP(*(.requests_end_marker))
+    } :data
+
+    /* NOTE: .bss needs to be the last thing mapped to :data, otherwise lots of */
+    /* unnecessary zeros will be written to the binary. */
+    /* If you need, for example, .init_array and .fini_array, those should be placed */
+    /* above this. */
+    .bss : {
+        *(.bss .bss.*)
+        *(COMMON)
+    } :data
+
+    /* Discard .note.* and .eh_frame* since they may cause issues on some hosts. */
+    /DISCARD/ : {
+        *(.eh_frame*)
+        *(.note .note.*)
+    }
+}

kernel/rust-toolchain.toml

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+[toolchain]
+channel = "nightly"
+targets = [
+    "x86_64-unknown-none",
+    # "aarch64-unknown-none",
+    # "riscv64gc-unknown-none-elf",
+    # "loongarch64-unknown-none",
+]

kernel/src/graphics.rs

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+use limine::framebuffer::Framebuffer;
+
+pub fn rgb(r: u8, g: u8, b: u8) -> u32 {
+    ((r as u32) << 16) | ((g as u32) << 8) | (b as u32)
+}
+
+pub fn create_rect(framebuffer: &Framebuffer, x: u64, y: u64, width: u64, height: u64, color: u32) {
+    for fb_x in x..x+width {
+        for fb_y in y..y+height {
+            // Calculate the pixel offset using the framebuffer information we obtained above.
+            // We skip `i` scanlines (pitch is provided in bytes) and add `i * 4` to skip `i` pixels forward.
+            let bytes_per_pixel = framebuffer.bpp() as u64 / 8;
+            let pixel_offset = fb_y * framebuffer.pitch() + fb_x * bytes_per_pixel;
+
+            // Write 0xFFFFFFFF to the provided pixel offset to fill it white.
+            unsafe {
+                framebuffer
+                    .addr()
+                    .add(pixel_offset as usize)
+                    .cast::<u32>()
+                    .write(color)
+            };
+        }
+    }
+}

kernel/src/main.rs

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+#![no_std]
+#![no_main]
+
+use core::arch::asm;
+
+use limine::BaseRevision;
+use limine::request::{FramebufferRequest, RequestsEndMarker, RequestsStartMarker};
+
+mod graphics;
+use crate::graphics::*;
+
+
+/// Sets the base revision to the latest revision supported by the crate.
+/// See specification for further info.
+/// Be sure to mark all limine requests with #[used], otherwise they may be removed by the compiler.
+#[used]
+// The .requests section allows limine to find the requests faster and more safely.
+#[unsafe(link_section = ".requests")]
+static BASE_REVISION: BaseRevision = BaseRevision::new();
+
+#[used]
+#[unsafe(link_section = ".requests")]
+static FRAMEBUFFER_REQUEST: FramebufferRequest = FramebufferRequest::new();
+
+/// Define the stand and end markers for Limine requests.
+#[used]
+#[unsafe(link_section = ".requests_start_marker")]
+static _START_MARKER: RequestsStartMarker = RequestsStartMarker::new();
+#[used]
+#[unsafe(link_section = ".requests_end_marker")]
+static _END_MARKER: RequestsEndMarker = RequestsEndMarker::new();
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn kmain() -> ! {
+    // All limine requests must also be referenced in a called function, otherwise they may be
+    // removed by the linker.
+    assert!(BASE_REVISION.is_supported());
+
+    if let Some(framebuffer_response) = FRAMEBUFFER_REQUEST.get_response() {
+        if let Some(framebuffer) = framebuffer_response.framebuffers().next() {
+            graphics::create_rect(&framebuffer, 0, 0, framebuffer.width(), framebuffer.height(), graphics::rgb(253, 129, 0));
+        }
+    }
+
+    hcf();
+}
+
+#[panic_handler]
+fn rust_panic(_info: &core::panic::PanicInfo) -> ! {
+    hcf();
+}
+
+fn hcf() -> ! {
+    loop {
+        unsafe {
+            #[cfg(target_arch = "x86_64")]
+            asm!("hlt");
+            #[cfg(any(target_arch = "aarch64", target_arch = "riscv64"))]
+            asm!("wfi");
+            #[cfg(target_arch = "loongarch64")]
+            asm!("idle 0");
+        }
+    }
+}