Build as a 'bin' crate, linking with rust-lld

This eliminated the two awkward `ld` steps from the Makefile, and seems
to produce a smaller `.efi`. It seems to work, based on quick testing in
qemu.

Using 'uefi' for target because apparently Rust cares:
rust-lang/rust#71881

Some changes to the target specification here are from
`rustc -Z unstable-options --print target-spec-json --target x86_64-unknown-uefi`.
We probably want more of the settings from there, but most likely still
need our own custom target to change some things.

Author: ids1024

Cargo.toml

@@ -3,11 +3,6 @@ name = "system76_firmware_setup"
 version = "1.0.0"
 edition = "2018"
 
-[lib]
-name = "system76_firmware_setup"
-path = "src/lib.rs"
-crate-type = ["staticlib"]
-
 [profile.release]
 lto = true
 

Makefile

@@ -1,4 +1,4 @@
-TARGET?=x86_64-efi-pe
+TARGET?=x86_64-uefi-pe
 
 export LD=ld
 export RUST_TARGET_PATH=$(CURDIR)/targets
@@ -40,40 +40,10 @@ $(BUILD)/efi.img: $(BUILD)/boot.efi
 	mcopy -i $@.tmp res/startup.nsh ::startup.nsh
 	mv $@.tmp $@
 
-$(BUILD)/boot.efi: $(BUILD)/boot.o
-	$(LD) \
-		-m i386pep \
-		--oformat pei-x86-64 \
-		--dll \
-		--image-base 0 \
-		--section-alignment 32 \
-		--file-alignment 32 \
-		--major-os-version 0 \
-		--minor-os-version 0 \
-		--major-image-version 0 \
-		--minor-image-version 0 \
-		--major-subsystem-version 0 \
-		--minor-subsystem-version 0 \
-		--subsystem 11 \
-		--heap 0,0 \
-		--stack 0,0 \
-		--pic-executable \
-		--entry _start \
-		--no-insert-timestamp \
-		$< -o $@
-		#--subsystem 10
-
-$(BUILD)/boot.o: $(BUILD)/boot.a
-	rm -rf $(BUILD)/boot
-	mkdir $(BUILD)/boot
-	cd $(BUILD)/boot && ar x ../boot.a
-	ld -r $(BUILD)/boot/*.o -o $@
-
-$(BUILD)/boot.a: Cargo.lock Cargo.toml res/* src/* src/*/*
+$(BUILD)/boot.efi: Cargo.lock Cargo.toml res/* src/* src/*/*
 	mkdir -p $(BUILD)
 	cargo rustc \
 		-Z build-std=core,alloc \
-		--lib \
 		--target $(TARGET) \
 		--release \
 		-- \

firmware-setup.inf

@@ -14,5 +14,5 @@
   VALID_ARCHITECTURES           = X64
 
 [Binaries.X64]
-  PE32|build/x86_64-efi-pe/boot.efi|*
+  PE32|build/x86_64-uefi-pe/boot.efi|*
 

src/lib.rs renamed to src/main.rs

@@ -1,4 +1,5 @@
 #![no_std]
+#![no_main]
 #![feature(llvm_asm)]
 #![feature(const_fn)]
 #![feature(core_intrinsics)]

targets/x86_64-efi-pe.json renamed to targets/x86_64-uefi-pe.json

@@ -1,27 +1,37 @@
 {
-    "linker": "false",
-    "linker-flavor": "ld",
-    "llvm-target": "x86_64-efi-pe",
+    "linker": "rust-lld",
+    "linker-flavor": "lld-link",
+    "lld-flavor": "link",
+    "llvm-target": "x86_64-unknown-windows",
     "target-endian": "little",
     "target-pointer-width": "64",
     "target-c-int-width": "32",
     "data-layout": "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128",
     "arch": "x86_64",
-    "os": "efi",
+    "os": "uefi",
     "env": "pe",
     "vendor": "unknown",
     "target-family": "none",
     "pre-link-args": {
-        "ld": ["-m64", "-nostdlib", "-static"]
+        "lld-link": [
+            "/entry:_start",
+            "/heap:0,0",
+            "/stack:0,0",
+            "/dll",
+            "/base:0",
+            "/align:32",
+            "/filealign:32",
+            "/subsystem:efi_boot_service_driver"
+        ]
     },
     "cpu": "core2",
     "features": "-mmx,-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-3dnow,-3dnowa,-avx,-avx2,+soft-float",
     "dynamic-linking": false,
-    "executables": false,
+    "executables": true,
     "relocation-model": "pic",
     "disable-redzone": true,
     "eliminate-frame-pointer": false,
-    "exe-suffix": "",
+    "exe-suffix": ".efi",
     "has-rpath": false,
     "no-compiler-rt": true,
     "no-default-libraries": true,