define custom target, use with cargo-xbuild

requires nixpkgs master now

.cargo/config

@@ -1,11 +1,11 @@
-[target.armv7-unknown-linux-gnueabihf]
+[target.armv7-none-eabihf]
 runner = "./runner.sh"
 linker = "arm-none-eabihf-gcc"
 rustflags = [
-  "-C", "link-arg=-Wl,-Tlink.x,-N",
+  "-C", "link-arg=-Tlink.x",
   "-C", "target-feature=a9,armv7-a,neon",
   "-C", "target-cpu=cortex-a9",
 ]
 
 [build]
-target = "armv7-unknown-linux-gnueabihf"
+target = "armv7-none-eabihf.json"

armv7-none-eabihf.json

@@ -0,0 +1,28 @@
+{
+  "abi-blacklist": [
+    "stdcall",
+    "fastcall",
+    "vectorcall",
+    "thiscall",
+    "win64",
+    "sysv64"
+  ],
+  "arch": "arm",
+  "data-layout": "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64",
+  "emit-debug-gdb-scripts": false,
+  "env": "",
+  "executables": true,
+  "features": "+v7,+vfp3,-d32,+thumb2,-neon",
+  "is-builtin": false,
+  "linker": "rust-lld",
+  "linker-flavor": "ld.lld",
+  "llvm-target": "armv7-unknown-none-eabihf",
+  "max-atomic-width": 32,
+  "os": "none",
+  "panic-strategy": "abort",
+  "relocation-model": "static",
+  "target-c-int-width": "32",
+  "target-endian": "little",
+  "target-pointer-width": "32",
+  "vendor": ""
+}

default.nix

@@ -1,6 +1,5 @@
 { # Use master branch of the overlay by default
   mozillaOverlay ? import (builtins.fetchTarball https://github.com/mozilla/nixpkgs-mozilla/archive/master.tar.gz),
-  rustSrc ? https://github.com/rustlang/rust/archive/master.tar.gz,
 }:
 
 let
@@ -8,15 +7,21 @@ let
 in
 with pkgs;
 let
+  rustcSrc = fetchgit {
+    url = https://github.com/rust-lang/rust.git;
+    # master of 2019-08-06
+    rev = "8996328ebf34aa73e83a1db326767c11041f811d";
+    sha256 = "1daz0y97dm35nfy7ip0wqvyax0g36szm25n77rcg20k6wab4fqi7";
+    fetchSubmodules = true;
+  };
   targets = [
-    "armv7-unknown-linux-gnueabihf"
   ];
   rust =
     rustChannelOfTargets "nightly" null targets;
   rustPlatform = recurseIntoAttrs (makeRustPlatform {
-    rustc = rust // { src = rustSrc; };
+    rustc = rust // { src = rustcSrc; };
     cargo = rust;
   });
 in {
-  inherit pkgs rustPlatform;
+  inherit pkgs rustPlatform rustcSrc;
 }

link.x

@@ -20,36 +20,45 @@ MEMORY
 
 SECTIONS
 {
-    .exceptions (0x0) :
+    .exceptions ORIGIN(OCM) :
     {
         KEEP(*(.text.exceptions));
     } > OCM
-    .text (0x8000) :
-    {
-        KEEP(*(.text.boot))
-        *(.text .text.*)
+
+    .__fill (NOLOAD) : {
+          . = ORIGIN(OCM) + 0x8000;
     } > OCM
 
-    .rodata ALIGN(0x1000) :
+    .text (ORIGIN(OCM) + 0x8000) :
     {
-        *(.rodata)
+        *(.text.boot);
+        *(.text .text.*);
+        . = ALIGN(4);
     } > OCM
  
-    .data ALIGN(0x1000) :
+    .rodata : ALIGN(4)
     {
-        *(.data)
+        *(.rodata .rodata.*);
+        . = ALIGN(4);
     } > OCM
  
-    .bss ALIGN(0x4000) (NOLOAD) :
+    .data : ALIGN(4)
+    {
+        *(.data .data.*);
+        . = ALIGN(4);
+    } > OCM
+ 
+    .bss (NOLOAD) : ALIGN(0x4000)
     {
         /* Aligned to 16 kB */
         KEEP(*(.bss.l1_table));
-        *(.bss)
+        *(.bss .bss.*);
+        . = ALIGN(4);
     } > OCM
     __bss_start = ADDR(.bss);
     __bss_end = ADDR(.bss) + SIZEOF(.bss);
 
-    .stack ALIGN(0x1000) (NOLOAD) : {
+    .stack (NOLOAD) : ALIGN(0x1000) {
       . += STACK_SIZE;
     } > OCM
     __stack_end = ADDR(.stack);
@@ -58,6 +67,7 @@ SECTIONS
   /DISCARD/ :
   {
     /* Unused exception related info that only wastes space */
+    *(.ARM.exidx);
     *(.ARM.exidx.*);
     *(.ARM.extab.*);
   }

shell.nix

@@ -11,6 +11,7 @@ stdenv.mkDerivation {
   name = "adc2tcp-env";
   buildInputs = with rustPlatform.rust; [
     rustc cargo
+    cargo-xbuild rustcSrc
     pkgsCross.armhf-embedded.buildPackages.gcc
     #pkgsCross.armv7l-hf-multiplatform.buildPackages.gcc
     #pkgsCross.armhf-embedded.buildPackages.binutils
@@ -18,7 +19,9 @@ stdenv.mkDerivation {
 
   # Set Environment Variables
   RUST_BACKTRACE = 1;
+  XARGO_RUST_SRC = "${rustcSrc}/src";
 
   shellHook = ''
+    echo "Run 'cargo xbuild --release' to build."
   '';
 }