Try to link as ELF64

Author: phil-opp

real_mode/.cargo/config

@@ -1,2 +1,2 @@
 [build]
-target = "x86_64-bootloader-real-mode.json"
+target = "x86_64-bootloader.json"

real_mode/Cargo.lock

@@ -1,5 +1,5 @@
 [package]
-name = "real_mode"
+name = "bootloader"
 version = "0.1.0"
 authors = ["Philipp Oppermann <[email protected]>"]
 edition = "2018"

real_mode/Cargo.toml

@@ -9,7 +9,7 @@ fn main() {
     let objcopy = llvm_tools.tool(&exe("llvm-objcopy")).expect("llvm-objcopy not found");
 
     build_subproject(Path::new("first_stage"), &["_start", "print_char"], &out_dir, &objcopy);
-    build_subproject(Path::new("second_stage"), &["second_stage"], &out_dir, &objcopy);
+    build_subproject(Path::new("real_mode"), &["second_stage"], &out_dir, &objcopy);
 }
 
 fn build_subproject(dir: &Path, global_symbols: &[&str], out_dir: &str, objcopy: &Path) {
@@ -21,11 +21,14 @@ fn build_subproject(dir: &Path, global_symbols: &[&str], out_dir: &str, objcopy:
     // build
     let mut cmd = Command::new("cargo");
     cmd.arg("xbuild").arg("--release");
+    cmd.arg("--verbose");
     cmd.arg(format!("--manifest-path={}", manifest_path.display()));
+    cmd.arg(format!("--target={}", dir.join("x86_64-target.json").display()));
     cmd.arg("-Z").arg("unstable-options");
     cmd.arg("--out-dir").arg(&out_dir);
-    cmd.arg("--target-dir").arg("target");
-    cmd.env("XBUILD_SYSROOT_PATH", format!("target/{}-sysroot", dir_name));
+    cmd.arg("--target-dir").arg(out_path.join("target").join(dir_name));
+    cmd.env_remove("RUSTFLAGS");
+    cmd.env("XBUILD_SYSROOT_PATH", out_path.join("target").join(dir_name).join("sysroot"));
     let status = cmd.status().unwrap();
     assert!(status.success());
 
@@ -37,6 +40,13 @@ fn build_subproject(dir: &Path, global_symbols: &[&str], out_dir: &str, objcopy:
     cmd.arg(out_path.join(format!("lib{}.a", dir_name)));
     let status = cmd.status().unwrap();
     assert!(status.success());
+    
+    // convert to ELF64
+    let mut cmd = Command::new(objcopy);
+    cmd.arg("-I").arg("elf32-i386").arg("-O").arg("elf64-x86-64");
+    cmd.arg(out_path.join(format!("lib{}.a", dir_name)));
+    let status = cmd.status().unwrap();
+    assert!(status.success());
 
     // emit linker flags
     println!("cargo:rustc-link-search=native={}", out_dir);

real_mode/build.rs

@@ -0,0 +1,26 @@
+{
+	"arch": "x86",
+	"cpu": "i386",
+	"data-layout": "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128",
+	"dynamic-linking": false,
+	"executables": true,
+	"linker-flavor": "ld.lld",
+	"linker": "rust-lld",
+	"llvm-target": "i386-unknown-none-code16",
+	"pre-link-args": {
+		"ld.lld": [
+			"-Tlinker.ld"
+		]
+	},
+	"max-atomic-width": 64,
+	"position-independent-executables": false,
+	"disable-redzone": true,
+	"target-c-int-width": "32",
+	"target-pointer-width": "32",
+	"target-endian": "little",
+	"panic-strategy": "abort",
+	"os": "none",
+	"vendor": "unknown",
+	"relocation_model": "static",
+	"eliminate_frame_pointer": true
+}

real_mode/first_stage/x86_64-target.json

@@ -30,15 +30,15 @@ SECTIONS {
 
     _second_stage_start = .;
 
-    .second_stage_text :
+    .real_mode_text :
     {
-        *second_stage*(.text .text.*)
+        *real_mode*(.text .text.*)
     }
-    .second_stage_data :
+    .real_mode_data :
     {
-        *second_stage*(.rodata .rodata.*)
-        *second_stage*(.data .data.*)
-        *second_stage*(.got .got.*)
+        *real_mode*(.rodata .rodata.*)
+        *real_mode*(.data .data.*)
+        *real_mode*(.got .got.*)
     }
 
     .text :

real_mode/linker.ld

@@ -1,13 +1,13 @@
 [package]
-name = "second_stage"
+name = "real_mode"
 version = "0.1.0"
 authors = ["Philipp Oppermann <[email protected]>"]
 edition = "2018"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [lib]
-name = "second_stage"
+name = "real_mode"
 crate-type = ["staticlib"]
 
 [dependencies]