fill in all those options.

src/librustc_target/spec/thumbv4t_nintendo_gba.rs

@@ -1,12 +1,11 @@
-//! Targets the Nintendo Game Boy Advance (GBA).
+//! Targets the Nintendo Game Boy Advance (GBA), a handheld game device from 2001.
 //!
-//! The GBA is a handheld game device from 2001. Inside, the CPU is an ARM7TDMI.
-//! That's in the ARMv4T architecture family.
+//! Please ping @Lokathor if changes are needed.
 //!
-//! Technically the device has no OS, however we're going to copy the
-//! `mipsel_sony_psp` target setup and set the OS string to be "GBA". Other than
-//! the setting of the `target_os` and `target_vendor` values, this target is a
-//! fairly standard configuration for `thumbv4t`
+//! Important: This target **does not** specify a linker script or the ROM
+//! header. You'll still need to provide these yourself to construct a final
+//! binary. Generally you'd do this with something like
+//! `-Clink-arg=-Tmy_script.ld` and `-Clink-arg=my_crt.o`.
 
 use crate::spec::{LinkerFlavor, LldFlavor, Target, TargetOptions, TargetResult};
 
@@ -16,14 +15,65 @@ pub fn target() -> TargetResult {
         target_endian: "little".to_string(),
         target_pointer_width: "32".to_string(),
         target_c_int_width: "32".to_string(),
-        target_os: "gba".to_string(),
-        target_env: String::new(),
+        target_os: "none".to_string(),
+        target_env: "gba".to_string(),
         target_vendor: "nintendo".to_string(),
         arch: "arm".to_string(),
-        data_layout: "TODO".to_string(),
+        /* Data layout args are '-' separated:
+         * little endian
+         * stack is 64-bit aligned (EABI)
+         * pointers are 32-bit
+         * i64 must be 64-bit aligned (EABI)
+         * mangle names with ELF style
+         * native integers are 32-bit
+         * All other elements are default
+         */
+        data_layout: "e-S64-p:32:32-i64:64-m:e-n32".to_string(),
         linker_flavor: LinkerFlavor::Ld,
         options: TargetOptions {
-            // TODO
+            linker: Some("arm-none-eabi-ld".to_string()),
+            linker_is_gnu: true,
+
+            // extra args passed to the external assembler
+            asm_args: vec!["-mcpu=arm7tdmi".to_string(), "-mthumb-interwork".to_string()],
+
+            cpu: "arm7tdmi".to_string(),
+
+            // minimum extra features, these cannot be disabled via -C
+            features: "+soft-float,+strict-align".to_string(),
+
+            executables: true,
+
+            relocation_model: RelocModel::Static,
+
+            //function_sections: bool,
+            //exe_suffix: String,
+            main_needs_argc_argv: false,
+
+            // if we have thread-local storage
+            has_elf_tls: false,
+
+            // don't have atomic compare-and-swap
+            atomic_cas: false,
+
+            // always just abort
+            panic_strategy: PanicStrategy::Abort,
+
+            // ABIs to not use
+            unsupported_abis: super::arm_base::unsupported_abis(),
+
+            // The minimum alignment for global symbols.
+            min_global_align: Some(4),
+
+            // no threads here
+            singlethread: true,
+
+            // GBA has no builtins
+            no_builtins: true,
+
+            // this is off just like in the `thumb_base`
+            emit_debug_gdb_scripts: false,
+
             ..TargetOptions::default()
         },
     })