rcutorture: Abstract qemu-flavor identification

The task of working out which flavor of qemu to use gets more complex
as more types of CPUs are supported.  Adding Power makes three in addition
to 32-bit and 64-bit x86, so it is time to pull this out into a function.
This commit therefore creates an identify_qemu function and also adds
a --qemu-cmd command-line argument for the inevitable case where the
identify_qemu cannot figure it out.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>

tools/testing/selftests/rcutorture/bin/functions.sh

@@ -51,3 +51,30 @@ configfrag_hotplug_cpu () {
 	fi
 	grep -q '^CONFIG_HOTPLUG_CPU=y$' "$1"
 }
+
+# identify_qemu builddir
+#
+# Returns our best guess as to which qemu command is appropriate for
+# the kernel at hand.  Override with the RCU_QEMU_CMD environment variable.
+identify_qemu () {
+	local u="`file "$1"`"
+	if test -n "$RCU_QEMU_CMD"
+	then
+		echo $RCU_QEMU_CMD
+	elif echo $u | grep -q x86-64
+	then
+		echo qemu-system-x86_64
+	elif echo $u | grep -q "Intel 80386"
+	then
+		echo qemu-system-i386
+	elif uname -a | grep -q ppc64
+	then
+		echo qemu-system-ppc64
+	else
+		echo Cannot figure out what qemu command to use! 1>&2
+		# Usually this will be one of /usr/bin/qemu-system-*
+		# Use RCU_QEMU_CMD environment variable or appropriate
+		# argument to top-level script.
+		exit 1
+	fi
+}

tools/testing/selftests/rcutorture/bin/kvm-test-1-rcu.sh

@@ -109,12 +109,9 @@ boot_args=$6
 cd $KVM
 kstarttime=`awk 'BEGIN { print systime() }' < /dev/null`
 echo ' ---' `date`: Starting kernel
-if file linux-2.6/*.o | grep -q 64-bit
-then
-	QEMU=qemu-system-x86_64
-else
-	QEMU=qemu-system-i386
-fi
+
+# Determine the appropriate flavor of qemu command.
+QEMU="`identify_qemu $builddir/vmlinux.o`"
 
 # Generate -smp qemu argument.
 cpu_count=`configNR_CPUS.sh $config_template`

tools/testing/selftests/rcutorture/bin/kvm.sh

@@ -45,6 +45,7 @@ usage () {
 	echo "       --datestamp string"
 	echo "       --duration minutes"
 	echo "       --kversion vN.NN"
+	echo "       --qemu-cmd qemu-system-..."
 	echo "       --rcu-kvm absolute-pathname"
 	echo "       --results absolute-pathname"
 	echo "       --relbuilddir relative-pathname"
@@ -101,6 +102,11 @@ do
 		kversion=$2
 		shift
 		;;
+	--qemu-cmd)
+		checkarg --qemu-cmd "(qemu-system-...)" $# "$2" 'qemu-system-' '^--'
+		RCU_QEMU_CMD="$2"; export RCU_QEMU_CMD
+		shift
+		;;
 	--rcu-kvm)
 		checkarg --rcu-kvm "(absolute pathname)" "$#" "$2" '^/' error
 		KVM=$2; export KVM