alnyan/yggdrasil: add linker script for yggdrasil target

compiler/rustc_target/src/spec/aarch64_unknown_yggdrasil.rs

@@ -1,12 +1,15 @@
 use crate::spec::{PanicStrategy, Target};
 
+// Have specific requirements about how segments are aligned
+const LINKER_SCRIPT: &str = include_str!("./aarch64_unknown_yggdrasil_linker_script.ld");
+
 pub fn target() -> Target {
     let mut base = super::yggdrasil_base::opts();
 
     base.disable_redzone = true;
     base.panic_strategy = PanicStrategy::Abort;
     base.features = "-fp-armv8,-neon,+strict-align,+v8a".into();
-    base.add_pre_link_args(super::LinkerFlavor::Unix(super::Cc::No), &["--entry=runtime_entry"]);
+    base.link_script = Some(LINKER_SCRIPT.into());
 
     Target {
         llvm_target: "aarch64-unknown-none".into(),

compiler/rustc_target/src/spec/aarch64_unknown_yggdrasil_linker_script.ld

@@ -0,0 +1,34 @@
+OUTPUT_FORMAT(elf64-littleaarch64)
+OUTPUT_ARCH(aarch64)
+ENTRY(runtime_entry)
+
+BASE_ADDR = 0x400000;
+
+SECTIONS {
+    . = BASE_ADDR;
+
+    .text : {
+        *(.text*)
+        *(.plt*)
+    }
+
+    . = ALIGN(4K);
+
+    .rodata : {
+        *(.rodata*)
+    }
+
+    . = ALIGN(4K);
+
+    .data : {
+        *(.data*)
+        *(.got*)
+    }
+
+    . = ALIGN(4K);
+
+    .bss : {
+        *(COMMON)
+        *(.bss*)
+    }
+}

compiler/rustc_target/src/spec/yggdrasil_base.rs

@@ -1,13 +1,13 @@
 use crate::spec::{Cc, LinkerFlavor, RelocModel, StackProbeType, TargetOptions};
 
-use super::LldFlavor;
+use super::{Lld, LldFlavor};
 
 pub fn opts() -> TargetOptions {
     TargetOptions {
         os: "yggdrasil".into(),
         executables: true,
         linker: Some("ld.lld".into()),
-        linker_flavor: LinkerFlavor::Unix(Cc::No),
+        linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
         lld_flavor_json: LldFlavor::Ld,
         stack_probes: StackProbeType::Inline,
         max_atomic_width: Some(128),