lib/systems: add mips64el definitions

MIPS has a large space of {architecture,abi,endianness}; this commit
adds all of them to lib/systems/platforms.nix so we can be done with
it.

Currently lib/systems/inspect.nix has a single "isMips" predicate,
which is a bit ambiguous now that we will have both mips32 and mips64
support, with the latter having two ABIs.  Let's add four new
predicates (isMips32, isMips64, isMips64n32, and isMips64n64) and
treat the now-ambiguous isMips as deprecated in favor of the
more-specific predicates.  These predicates are used mainly for
enabling/disabling target-specific workarounds, and it is extremely
rare that a platform-specific workaround is needed, and both mips32
and mips64 need exactly the same workaround.

The separate predicates (isMips64n32 and isMips64n64) for ABI
distinctions are, unfortunately, useful.  Boost's user-scheduled
threading (used by nix) does does not currently supports mips64n32,
which is a very desirable ABI on routers since they rarely have
more than 2**32 bytes of DRAM.

lib/systems/default.nix

@@ -105,7 +105,8 @@ rec {
         else if final.isAarch64 then "arm64"
         else if final.isx86_32 then "i386"
         else if final.isx86_64 then "x86_64"
-        else if final.isMips then "mips"
+        else if final.isMips32 then "mips"
+        else if final.isMips64 then "mips"    # linux kernel does not distinguish mips32/mips64
         else if final.isPower then "powerpc"
         else if final.isRiscV then "riscv"
         else if final.isS390 then "s390"

lib/systems/doubles.nix

@@ -26,7 +26,7 @@ let
 
     # Linux
     "aarch64-linux" "armv5tel-linux" "armv6l-linux" "armv7a-linux"
-    "armv7l-linux" "i686-linux" "m68k-linux" "mipsel-linux"
+    "armv7l-linux" "i686-linux" "m68k-linux" "mipsel-linux" "mips64el-linux"
     "powerpc64-linux" "powerpc64le-linux" "riscv32-linux"
     "riscv64-linux" "s390-linux" "s390x-linux" "x86_64-linux"
 
@@ -87,7 +87,11 @@ in {
   darwin        = filterDoubles predicates.isDarwin;
   freebsd       = filterDoubles predicates.isFreeBSD;
   # Should be better, but MinGW is unclear.
-  gnu           = filterDoubles (matchAttrs { kernel = parse.kernels.linux; abi = parse.abis.gnu; }) ++ filterDoubles (matchAttrs { kernel = parse.kernels.linux; abi = parse.abis.gnueabi; }) ++ filterDoubles (matchAttrs { kernel = parse.kernels.linux; abi = parse.abis.gnueabihf; });
+  gnu           = filterDoubles (matchAttrs { kernel = parse.kernels.linux; abi = parse.abis.gnu; })
+                  ++ filterDoubles (matchAttrs { kernel = parse.kernels.linux; abi = parse.abis.gnueabi; })
+                  ++ filterDoubles (matchAttrs { kernel = parse.kernels.linux; abi = parse.abis.gnueabihf; })
+                  ++ filterDoubles (matchAttrs { kernel = parse.kernels.linux; abi = parse.abis.gnuabin32; })
+                  ++ filterDoubles (matchAttrs { kernel = parse.kernels.linux; abi = parse.abis.gnuabi64; });
   illumos       = filterDoubles predicates.isSunOS;
   linux         = filterDoubles predicates.isLinux;
   netbsd        = filterDoubles predicates.isNetBSD;

lib/systems/examples.nix

@@ -93,6 +93,10 @@ rec {
     config = "mipsel-unknown-linux-gnu";
   } // platforms.fuloong2f_n32;
 
+  mips64el-linux-gnuabin32      = platforms.mips64el-linux-gnuabin32;
+  mips64el-linux-gnuabi64       = platforms.mips64el-linux-gnuabi64  // { rustc.config = "mips64el-unknown-linux-gnuabi64"; };
+  mips64el-qemu-linux-gnuabi64  = platforms.mips64el-qemu-linux-gnuabi64;
+
   muslpi = raspberryPi // {
     config = "armv6l-unknown-linux-musleabihf";
   };

lib/systems/inspect.nix

@@ -17,6 +17,10 @@ rec {
     isAarch32      = { cpu = { family = "arm"; bits = 32; }; };
     isAarch64      = { cpu = { family = "arm"; bits = 64; }; };
     isMips         = { cpu = { family = "mips"; }; };
+    isMips32       = { cpu = { family = "mips"; bits = 32; }; };
+    isMips64       = { cpu = { family = "mips"; bits = 64; }; };
+    isMips64n32    = { cpu = { family = "mips"; bits = 64; }; abi = { abi = "n32"; }; };
+    isMips64n64    = { cpu = { family = "mips"; bits = 64; }; abi = { abi = "64";  }; };
     isMmix         = { cpu = { family = "mmix"; }; };
     isRiscV        = { cpu = { family = "riscv"; }; };
     isSparc        = { cpu = { family = "sparc"; }; };
@@ -57,7 +61,7 @@ rec {
 
     isAndroid      = [ { abi = abis.android; } { abi = abis.androideabi; } ];
     isGnu          = with abis; map (a: { abi = a; }) [ gnuabi64 gnu gnueabi gnueabihf ];
-    isMusl         = with abis; map (a: { abi = a; }) [ musl musleabi musleabihf ];
+    isMusl         = with abis; map (a: { abi = a; }) [ musl musleabi musleabihf muslabin32 muslabi64 ];
     isUClibc       = with abis; map (a: { abi = a; }) [ uclibc uclibceabi uclibceabihf ];
 
     isEfi          = map (family: { cpu.family = family; })

lib/systems/parse.nix

@@ -359,6 +359,13 @@ rec {
       ];
     };
     gnuabi64     = { abi = "64"; };
+    muslabi64    = { abi = "64"; };
+
+    # NOTE: abi=n32 requires a 64-bit MIPS chip!  That is not a typo.
+    # It is basically the 64-bit abi with 32-bit pointers.  Details:
+    # https://www.linux-mips.org/pub/linux/mips/doc/ABI/MIPS-N32-ABI-Handbook.pdf
+    gnuabin32    = { abi = "n32"; };
+    muslabin32   = { abi = "n32"; };
 
     musleabi     = { float = "soft"; };
     musleabihf   = { float = "hard"; };

lib/systems/platforms.nix

@@ -482,6 +482,55 @@ rec {
     };
   };
 
+  # MIPS ABI table transcribed from here: https://wiki.debian.org/Multiarch/Tuples
+
+  # can execute on 32bit chip
+  mips-linux-gnu                = { config = "mips-linux-gnu";                gcc = { arch = "mips32r2"; abi = "o32"; float = "hard"; }; };
+  mipsel-linux-gnu              = { config = "mipsel-linux-gnu";              gcc = { arch = "mips32r2"; abi = "o32"; float = "hard"; }; };
+  mipsisa32r6-linux-gnu         = { config = "mipsisa32r6-linux-gnu";         gcc = { arch = "mips32r6"; abi = "o32"; float = "hard"; }; };
+  mipsisa32r6el-linux-gnu       = { config = "mipsisa32r6el-linux-gnu";       gcc = { arch = "mips32r6"; abi = "o32"; float = "hard"; }; };
+
+  # require 64bit chip (for more registers, 64-bit floating point, 64-bit "long long") but use 32bit pointers
+  mips64-linux-gnuabin32        = { config = "mips64-linux-gnuabin32";        gcc = { arch = "mips64r2"; abi = "n32"; float = "hard"; }; };
+  mips64el-linux-gnuabin32      = { config = "mips64el-linux-gnuabin32";      gcc = { arch = "mips64r2"; abi = "n32"; float = "hard"; }; };
+  mipsisa64r6-linux-gnuabin32   = { config = "mipsisa64r6-linux-gnuabin32";   gcc = { arch = "mips64r6"; abi = "n32"; float = "hard"; }; };
+  mipsisa64r6el-linux-gnuabin32 = { config = "mipsisa64r6el-linux-gnuabin32"; gcc = { arch = "mips64r6"; abi = "n32"; float = "hard"; }; };
+
+  # 64bit pointers
+  mips64-linux-gnuabi64         = { config = "mips64-linux-gnuabi64";         gcc = { arch = "mips64r2"; abi =  "64"; float = "hard"; }; };
+  mips64el-linux-gnuabi64       = { config = "mips64el-linux-gnuabi64";       gcc = { arch = "mips64r2"; abi =  "64"; float = "hard"; }; };
+  mipsisa64r6-linux-gnuabi64    = { config = "mipsisa64r6-linux-gnuabi64";    gcc = { arch = "mips64r6"; abi =  "64"; float = "hard"; }; };
+  mipsisa64r6el-linux-gnuabi64  = { config = "mipsisa64r6el-linux-gnuabi64";  gcc = { arch = "mips64r6"; abi =  "64"; float = "hard"; }; };
+
+  # based on:
+  #   https://www.mail-archive.com/qemu-discuss@nongnu.org/msg05179.html
+  #   https://gmplib.org/~tege/qemu.html#mips64-debian
+  mips64el-qemu-linux-gnuabi64 = mips64el-linux-gnuabi64 // {
+    linux-kernel = {
+      name = "mips64el";
+      baseConfig = "64r2el_defconfig";
+      target = "vmlinuz";
+      autoModules = false;
+      DTB = true;
+      # for qemu 9p passthrough filesystem
+      extraConfig = ''
+        MIPS_MALTA y
+        PAGE_SIZE_4KB y
+        CPU_LITTLE_ENDIAN y
+        CPU_MIPS64_R2 y
+        64BIT y
+        CPU_MIPS64_R2 y
+
+        NET_9P y
+        NET_9P_VIRTIO y
+        9P_FS y
+        9P_FS_POSIX_ACL y
+        PCI y
+        VIRTIO_PCI y
+      '';
+    };
+  };
+
   ##
   ## Other
   ##

lib/tests/systems.nix

@@ -17,7 +17,7 @@ with lib.systems.doubles; lib.runTests {
 
   testarm = mseteq arm [ "armv5tel-linux" "armv6l-linux" "armv6l-netbsd" "armv6l-none" "armv7a-linux" "armv7a-netbsd" "armv7l-linux" "armv7l-netbsd" "arm-none" "armv7a-darwin" ];
   testi686 = mseteq i686 [ "i686-linux" "i686-freebsd" "i686-genode" "i686-netbsd" "i686-openbsd" "i686-cygwin" "i686-windows" "i686-none" "i686-darwin" ];
-  testmips = mseteq mips [ "mipsel-linux" "mipsel-netbsd" ];
+  testmips = mseteq mips [ "mips64el-linux" "mipsel-linux" "mipsel-netbsd" ];
   testmmix = mseteq mmix [ "mmix-mmixware" ];
   testx86_64 = mseteq x86_64 [ "x86_64-linux" "x86_64-darwin" "x86_64-freebsd" "x86_64-genode" "x86_64-redox" "x86_64-openbsd" "x86_64-netbsd" "x86_64-cygwin" "x86_64-solaris" "x86_64-windows" "x86_64-none" ];
 
@@ -28,7 +28,7 @@ with lib.systems.doubles; lib.runTests {
   testredox = mseteq redox [ "x86_64-redox" ];
   testgnu = mseteq gnu (linux /* ++ kfreebsd ++ ... */);
   testillumos = mseteq illumos [ "x86_64-solaris" ];
-  testlinux = mseteq linux [ "aarch64-linux" "armv5tel-linux" "armv6l-linux" "armv7a-linux" "armv7l-linux" "i686-linux" "mipsel-linux" "riscv32-linux" "riscv64-linux" "x86_64-linux" "powerpc64-linux" "powerpc64le-linux" "m68k-linux" "s390-linux" "s390x-linux" ];
+  testlinux = mseteq linux [ "aarch64-linux" "armv5tel-linux" "armv6l-linux" "armv7a-linux" "armv7l-linux" "i686-linux" "mips64el-linux" "mipsel-linux" "riscv32-linux" "riscv64-linux" "x86_64-linux" "powerpc64-linux" "powerpc64le-linux" "m68k-linux" "s390-linux" "s390x-linux" ];
   testnetbsd = mseteq netbsd [ "aarch64-netbsd" "armv6l-netbsd" "armv7a-netbsd" "armv7l-netbsd" "i686-netbsd" "m68k-netbsd" "mipsel-netbsd" "powerpc-netbsd" "riscv32-netbsd" "riscv64-netbsd" "x86_64-netbsd" ];
   testopenbsd = mseteq openbsd [ "i686-openbsd" "x86_64-openbsd" ];
   testwindows = mseteq windows [ "i686-cygwin" "x86_64-cygwin" "i686-windows" "x86_64-windows" ];

pkgs/stdenv/default.nix

@@ -53,6 +53,7 @@ in
     armv8m-linux = stagesLinux;
     aarch64-linux = stagesLinux;
     mipsel-linux = stagesLinux;
+    mips64el-linux = stagesLinux;
     powerpc-linux = /* stagesLinux */ stagesNative;
     powerpc64-linux = stagesLinux;
     powerpc64le-linux = stagesLinux;

pkgs/stdenv/linux/make-bootstrap-tools-cross.nix

@@ -17,6 +17,8 @@ in lib.mapAttrs (n: make) (with lib.systems.examples; {
   armv6l-musl  = muslpi;
   aarch64-musl = aarch64-multiplatform-musl;
   riscv64 = riscv64;
+  mips64el-linux-gnuabin32 = lib.systems.platforms.mips64el-linux-gnuabin32;
+  mips64el-linux-gnuabi64  = lib.systems.platforms.mips64el-linux-gnuabi64;
   powerpc64 = ppc64;
   powerpc64-musl = ppc64-musl;
   powerpc64le = powernv;

pkgs/top-level/stage.nix

@@ -64,6 +64,30 @@
 } @args:
 
 let
+  # This is a function from parsed platforms (like
+  # stdenv.hostPlatform.parsed) to parsed platforms.
+  makeStaticParsedPlatform = parsed:
+    # The following line guarantees that the output of this function
+    # is a well-formed platform with no missing fields.  It will be
+    # uncommented in a separate PR, in case it breaks the build.
+    #(x: lib.trivial.pipe x [ (x: builtins.removeAttrs x [ "_type" ]) lib.systems.parse.mkSystem ])
+      (parsed // {
+        abi = {
+          gnu = lib.systems.parse.abis.musl;
+          gnueabi = lib.systems.parse.abis.musleabi;
+          gnueabihf = lib.systems.parse.abis.musleabihf;
+          musleabi = lib.systems.parse.abis.musleabi;
+          musleabihf = lib.systems.parse.abis.musleabihf;
+          gnuabin32 = lib.systems.parse.abis.muslabin32;
+          gnuabi64 = lib.systems.parse.abis.muslabi64;
+          # The following two entries ensure that this function is idempotent.
+          muslabin32 = lib.systems.parse.abis.muslabin32;
+          muslabi64 = lib.systems.parse.abis.muslabi64;
+        }.${parsed.abi.name}
+          or lib.systems.parse.abis.musl;
+      });
+
+
   stdenvAdapters = self: super:
     let
       res = import ../stdenv/adapters.nix {
@@ -188,14 +212,7 @@ let
       })] ++ overlays;
       ${if stdenv.hostPlatform == stdenv.buildPlatform
         then "localSystem" else "crossSystem"} = {
-        parsed = stdenv.hostPlatform.parsed // {
-          abi = {
-            gnu = lib.systems.parse.abis.musl;
-            gnueabi = lib.systems.parse.abis.musleabi;
-            gnueabihf = lib.systems.parse.abis.musleabihf;
-          }.${stdenv.hostPlatform.parsed.abi.name}
-            or lib.systems.parse.abis.musl;
-        };
+        parsed = makeStaticParsedPlatform stdenv.hostPlatform.parsed;
       };
     } else throw "Musl libc only supports Linux systems.";
 
@@ -239,16 +256,7 @@ let
     } // lib.optionalAttrs stdenv.hostPlatform.isLinux {
       crossSystem = {
         isStatic = true;
-        parsed = stdenv.hostPlatform.parsed // {
-          abi = {
-            gnu = lib.systems.parse.abis.musl;
-            gnueabi = lib.systems.parse.abis.musleabi;
-            gnueabihf = lib.systems.parse.abis.musleabihf;
-            musleabi = lib.systems.parse.abis.musleabi;
-            musleabihf = lib.systems.parse.abis.musleabihf;
-          }.${stdenv.hostPlatform.parsed.abi.name}
-            or lib.systems.parse.abis.musl;
-        };
+        parsed = makeStaticParsedPlatform stdenv.hostPlatform.parsed;
       } // lib.optionalAttrs (stdenv.hostPlatform.system == "powerpc64-linux") {
         gcc.abi = "elfv2";
       };