configure: Allow builds without any system or user emulation

The old code aborted configure when no emulation target was selected.
Even after removing the 'exit 1', it tried to read from STDIN
when QEMU was configured with

    configure' '--disable-user' '--disable-system'

This is fixed here.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
(cherry picked from commit 8bdd3d499fe0ddffa9901c56ab3bc8911d5b8be0)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

2 files changed, 5 insertions, 4 deletions

diff --git a/Makefile b/Makefile
index 1cd5bc80d5..dd11e3c2d5 100644
--- a/Makefile
+++ b/Makefile
@@ -52,8 +52,13 @@ SUBDIR_MAKEFLAGS=$(if $(V),,--no-print-directory) BUILD_DIR=$(BUILD_DIR)
 SUBDIR_DEVICES_MAK=$(patsubst %, %/config-devices.mak, $(TARGET_DIRS))
 SUBDIR_DEVICES_MAK_DEP=$(patsubst %, %/config-devices.mak.d, $(TARGET_DIRS))
 
+ifeq ($(SUBDIR_DEVICES_MAK),)
+config-all-devices.mak:
+	$(call quiet-command,echo '# no devices' > $@,"  GEN   $@")
+else
 config-all-devices.mak: $(SUBDIR_DEVICES_MAK)
 	$(call quiet-command,cat $(SUBDIR_DEVICES_MAK) | grep =y | sort -u > $@,"  GEN   $@")
+endif
 
 -include $(SUBDIR_DEVICES_MAK_DEP)
 
diff --git a/configure b/configure
index ddf177a248..bf1863e408 100755
--- a/configure
+++ b/configure
@@ -1286,10 +1286,6 @@ if test -z "$target_list" ; then
 else
     target_list=`echo "$target_list" | sed -e 's/,/ /g'`
 fi
-if test -z "$target_list" ; then
-    echo "No targets enabled"
-    exit 1
-fi
 # see if system emulation was really requested
 case " $target_list " in
   *"-softmmu "*) softmmu=yes