gnu: Add qemu-minimal.

* gnu/packages/qemu.scm (qemu): Exchange with former QEMU-HEADLESS.
(qemu-headless): Rename to...
(qemu-minimal): ... this.  New variable.  Pass --target-list.
* gnu/packages/debug.scm (qemu-2.3.0): Inherit from QEMU-MINIMAL.
* gnu/packages/grub.scm (qemu-for-tests): Likewise.
* gnu/system/vm.scm (expression->derivation-in-linux-vm, qemu-image):
Update to name change.

gnu/packages/qemu.scm

@@ -38,7 +38,8 @@
   #:use-module (gnu packages xdisorg)
   #:use-module (gnu packages gl)
   #:use-module (gnu packages sdl)
-  #:use-module (gnu packages perl))
+  #:use-module (gnu packages perl)
+  #:use-module (srfi srfi-1))
 
 (define (qemu-patch commit file-name sha256)
   "Return an origin for COMMIT."
@@ -62,10 +63,9 @@
               (base32
                "1aicbplzdj5s5y13jmqyvfajay05x9dnkzd197waz8v6kha7d9d5")))
 
-(define-public qemu-headless
-  ;; This is QEMU without GUI support.
+(define-public qemu
   (package
-    (name "qemu-headless")
+    (name "qemu")
     (version "2.4.0.1")
     (source (origin
              (method url-fetch)
@@ -123,7 +123,11 @@
                   %standard-phases))))
 
     (inputs                                       ; TODO: Add optional inputs.
-     `(;; ("libaio" ,libaio)
+     `(("sdl" ,sdl)
+       ("mesa" ,mesa)
+       ("libusb" ,libusb)                         ;USB pass-through support
+
+       ;; ("libaio" ,libaio)
        ("glib" ,glib)
        ("ncurses" ,ncurses)
        ("libpng" ,libpng)
@@ -143,7 +147,7 @@
                      ("texinfo" ,texinfo)
                      ("perl" ,perl)))
     (home-page "http://www.qemu-project.org")
-    (synopsis "Machine emulator and virtualizer (without GUI)")
+    (synopsis "Machine emulator and virtualizer")
     (description
      "QEMU is a generic machine emulator and virtualizer.
 
@@ -163,12 +167,17 @@ server and embedded PowerPC, and S390 guests.")
     ;; Several tests fail on MIPS; see <http://hydra.gnu.org/build/117914>.
     (supported-systems (delete "mips64el-linux" %supported-systems))))
 
-(define-public qemu
-  ;; QEMU with GUI support.
-  (package (inherit qemu-headless)
-    (name "qemu")
-    (synopsis "Machine emulator and virtualizer")
-    (inputs `(("sdl" ,sdl)
-              ("mesa" ,mesa)
-              ("libusb" ,libusb)                  ;USB pass-through support
-              ,@(package-inputs qemu-headless)))))
+(define-public qemu-minimal
+  ;; QEMU without GUI support.
+  (package (inherit qemu)
+    (name "qemu-minimal")
+    (synopsis "Machine emulator and virtualizer (without GUI)")
+    (arguments
+     `(#:configure-flags
+       ;; Restrict to the targets supported by Guix.
+       '("--target-list=i386-softmmu,x86_64-softmmu,mips64el-softmmu,arm-softmmu")
+       ,@(package-arguments qemu)))
+
+    ;; Remove dependencies on optional libraries, notably GUI libraries.
+    (inputs (fold alist-delete (package-inputs qemu)
+                  '("sdl" "mesa" "libusb")))))