gnu: Add toolchain support for 'armhf-linux'.

Based on preliminary work by John Darrington <john@darrington.wattle.id.au>.

* gnu/packages/cross-base.scm (xgcc-armhf): New variable.
* gnu/packages/gcc.scm (gcc-configure-flags-for-triplet): Add armhf case.
  (gcc-4.7)[pre-configure]: Add gcc/config/*/linux-eabi.h to the list
  of files in which to patch GLIBC_DYNAMIC_LINKER.
* gnu/packages/bootstrap.scm (glibc-dynamic-linker): Add armhf case.
* guix/utils.scm (gnu-triplet->nix-system, nix-system->gnu-triplet):
  Add armhf cases.

gnu/packages/bootstrap.scm

@@ -162,6 +162,7 @@ successful, or false to signal an error."
   "Return the name of Glibc's dynamic linker for SYSTEM."
   (cond ((string=? system "x86_64-linux") "/lib/ld-linux-x86-64.so.2")
         ((string=? system "i686-linux") "/lib/ld-linux.so.2")
+        ((string=? system "armhf-linux") "/lib/ld-linux-armhf.so.3")
         ((string=? system "mips64el-linux") "/lib/ld.so.1")
 
         ;; XXX: This one is used bare-bones, without a libc, so add a case

gnu/packages/cross-base.scm

@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2014, 2015 Mark H Weaver <mhw@netris.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -322,6 +323,12 @@ XBINUTILS and the cross tool chain."
   ;; Bare-bones Xtensa cross-compiler, used to build the Atheros firmware.
   (cross-gcc "xtensa-elf"))
 
+(define-public xgcc-armhf
+  (let ((triplet "arm-linux-gnueabihf"))
+    (cross-gcc triplet
+               (cross-binutils triplet)
+               (cross-libc triplet))))
+
 ;; (define-public xgcc-armel
 ;;   (let ((triplet "armel-linux-gnueabi"))
 ;;     (cross-gcc triplet

gnu/packages/gcc.scm

@@ -46,8 +46,17 @@ where the OS part is overloaded to denote a specific ABI---into GCC
          ;; Triplets recognized by glibc as denoting the N64 ABI; see
          ;; ports/sysdeps/mips/preconfigure.
          '("--with-abi=64"))
+
+        ((string-match "^arm.*-gnueabihf$" target)
+         '("--with-arch=armv7-a"
+           "--with-float=hard"
+           "--with-mode=thumb"
+
+           ;; See <https://wiki.debian.org/ArmHardFloatPort/VfpComparison#FPU>
+           "--with-fpu=vfpv3-d16"))
+
         (else
-         ;; TODO: Add `armel.*gnueabi', `hf', etc.
+         ;; TODO: Add `arm.*-gnueabi', etc.
          '())))
 
 (define-public gcc-4.7
@@ -184,14 +193,14 @@ where the OS part is overloaded to denote a specific ABI---into GCC
                 (for-each
                  (lambda (x)
                    (substitute* (find-files "gcc/config"
-                                            "^linux(64|-elf)?\\.h$")
+                                            "^linux(64|-elf|-eabi)?\\.h$")
                      (("(#define GLIBC_DYNAMIC_LINKER.*)\\\\\n$" _ line)
                       line)))
                  '(1 2 3))
 
                 ;; Fix the dynamic linker's file name.
                 (substitute* (find-files "gcc/config"
-                                         "^linux(64|-elf)?\\.h$")
+                                         "^linux(64|-elf|-eabi)?\\.h$")
                   (("#define GLIBC_DYNAMIC_LINKER([^ ]*).*$" _ suffix)
                    (format #f "#define GLIBC_DYNAMIC_LINKER~a \"~a\"~%"
                            suffix

guix/utils.scm

@@ -1,6 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2012, 2013, 2014 Ludovic Courtès <ludo@gnu.org>
-;;; Copyright © 2013 Mark H Weaver <mhw@netris.org>
+;;; Copyright © 2013, 2014, 2015 Mark H Weaver <mhw@netris.org>
 ;;; Copyright © 2014 Eric Bavier <bavier@member.fsf.org>
 ;;; Copyright © 2014 Ian Denhardt <ian@zenhack.net>
 ;;;
@@ -481,14 +481,18 @@ previous value of the keyword argument."
           #:optional (system (%current-system)) (vendor "unknown"))
   "Return a guess of the GNU triplet corresponding to Nix system
 identifier SYSTEM."
-  (let* ((dash (string-index system #\-))
+  (match system
-         (arch (substring system 0 dash))
+    ("armhf-linux"
-         (os   (substring system (+ 1 dash))))
+     (string-append "arm-" vendor "-linux-gnueabihf"))
-    (string-append arch
+    (_
-                   "-" vendor "-"
+     (let* ((dash (string-index system #\-))
-                   (if (string=? os "linux")
+            (arch (substring system 0 dash))
-                       "linux-gnu"
+            (os   (substring system (+ 1 dash))))
-                       os))))
+       (string-append arch
+                      "-" vendor "-"
+                      (if (string=? os "linux")
+                          "linux-gnu"
+                          os))))))
 
 (define (gnu-triplet->nix-system triplet)
   "Return the Nix system type corresponding to TRIPLET, a GNU triplet as
@@ -498,7 +502,9 @@ returned by `config.guess'."
                         (lambda (m)
                           (string-append "i686-" (match:substring m 1))))
                        (else triplet))))
-    (cond ((string-match "^([^-]+)-([^-]+-)?linux-gnu.*" triplet)
+    (cond ((string-match "^arm[^-]*-([^-]+-)?linux-gnueabihf" triplet)
+           "armhf-linux")
+          ((string-match "^([^-]+)-([^-]+-)?linux-gnu.*" triplet)
            =>
            (lambda (m)
              ;; Nix omits `-gnu' for GNU/Linux.