From be4a7a3e8062483e252907a816a36798c42583c7 Mon Sep 17 00:00:00 2001
From: Michael Zhang <mail@mzhang.io>
Date: Thu, 5 Dec 2024 16:58:05 -0600
Subject: [PATCH] wip

---
 .cargo/config.toml | 10 ++++++++--
 Cargo.lock         |  2 +-
 Cargo.toml         |  5 ++++-
 Makefile           | 11 +++++------
 scripts/start.sh   |  9 ++++++---
 src/asm/entry.S    |  3 +++
 src/ld/kernel.ld   |  9 +++++++--
 src/main.rs        |  3 +--
 8 files changed, 35 insertions(+), 17 deletions(-)
 create mode 100644 src/asm/entry.S

diff --git a/.cargo/config.toml b/.cargo/config.toml
index 74fc137..7455ae8 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -2,8 +2,14 @@
 target = "riscv64gc-unknown-none-elf"
 
 [target.riscv64gc-unknown-none-elf]
-rustflags = ["-C", "link-arg=-Tsrc/ld/kernel.ld"]
-runner = "./scripts/start.sh"
+rustflags = [
+    "--print",
+    "link-args",
+    "-C",
+    "link-arg=--script",
+    "-C",
+    "link-arg=src/ld/kernel.ld",
+]
 
 [term]
 verbose = true
diff --git a/Cargo.lock b/Cargo.lock
index 09719f8..0dd1539 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3,5 +3,5 @@
 version = 3
 
 [[package]]
-name = "eos0"
+name = "kernel"
 version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
index 3045943..350045b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,9 @@
 [package]
-name = "eos0"
+name = "kernel"
 version = "0.1.0"
 edition = "2021"
 
+[profile.dev]
+panic = "abort"
+
 [dependencies]
diff --git a/Makefile b/Makefile
index 030026e..d1e4940 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,7 @@
-KERNEL = target/riscv64gc-unknown-none-elf/debug/xv6-riscv-rust
-SOURCES := $(shell find -name "*.rs")
+KERNEL = target/riscv64gc-unknown-none-elf/debug/kernel
+SOURCES := $(shell find . -name "*.rs")
+
+.PHONY: $(KERNEL)
 
 $(KERNEL): $(SOURCES)
-	cargo build
-
-fs.img: mkfs/mkfs README.md $(UPROGS)
-	mkfs/mkfs fs.img README.md $(UPROGS)
+	cargo rustc
diff --git a/scripts/start.sh b/scripts/start.sh
index d4adc4f..c9d7e36 100755
--- a/scripts/start.sh
+++ b/scripts/start.sh
@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
+set -x
+
 KERNEL=$1
 shift
 
@@ -8,7 +10,8 @@ qemu-system-riscv64 \
     -machine virt \
     -bios none \
     -m 3G \
-    -smp 3 \
-    # -drive file=fs.img,if=none,format=raw,id=x0 \
-    -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0 \
+    -d trace:exec_tb \
     -kernel "$KERNEL"
+
+    # -smp 3 \
+    # -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0 \
diff --git a/src/asm/entry.S b/src/asm/entry.S
new file mode 100644
index 0000000..ea3b692
--- /dev/null
+++ b/src/asm/entry.S
@@ -0,0 +1,3 @@
+.global _entry
+_entry:
+    call start
diff --git a/src/ld/kernel.ld b/src/ld/kernel.ld
index 9207f40..03d4625 100644
--- a/src/ld/kernel.ld
+++ b/src/ld/kernel.ld
@@ -3,10 +3,15 @@ ENTRY(_entry)
 
 SECTIONS {
     /*
-    It seems that QEMU jumps to 0x8000000 after setting up memory, so we want
+    It seems that QEMU jumps to 0x80000000 after setting up memory, so we want
     our kernel code to begin here.
 
     TODO: Is there an authoritative source that says that this is the address?
+    How to test this: Run QEMU using -d trace:exec_tb and see where the PC goes
     */
-    . = 0x8000000;
+    . = 0x80000000;
+
+    .text : {
+        *(.text)
+    }
 }
diff --git a/src/main.rs b/src/main.rs
index 0587db5..5559c4f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,8 +10,7 @@ fn panic_handler(_: &PanicInfo) -> ! {
 
 static HELLO: &[u8] = b"Hello World!";
 
-#[no_mangle]
-pub extern "C" fn _start() -> ! {
+pub extern "C" fn start() -> ! {
     let vga_buffer = 0xb8000 as *mut u8;
 
     for (i, &byte) in HELLO.iter().enumerate() {