kvm-unit-test: more documentation and runner script

Add documentation about using qemu-system for unit tests.
Add runner script to select the correct binary and flags.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

README

@@ -10,10 +10,23 @@ To create the tests' images just type 'make' in this directory.
 Tests' images created in ./<ARCH>/*.flat
 
 An example of a test invocation:
-qemu-system-x86_64 -device testdev,chardev=testlog -chardev file,id=testlog,path=msr.out -serial stdio -kernel ./x86/msr.flat
+Using qemu-kvm:
+
+qemu-kvm -device testdev,chardev=testlog -chardev file,id=testlog,path=msr.out -serial stdio -kernel ./x86/msr.flat
 This invocation runs the msr test case. The test outputs to stdio.
 
+Using qemu (supported since qemu 1.3):
+qemu-system-x86_64 -enable-kvm -device pc-testdev -serial stdio -device isa-debug-exit,iobase=0xf4,iosize=0x4 -kernel ./x86/msr.flat
+
+Or use a runner script to detect the correct invocation:
+./x86-run ./x86/msr.flat
+To select a specific qemu binary, specify the QEMU=<path> environment:
+QEMU=/tmp/qemu/x86_64-softmmu/qemu-system-x86_64 ./x86-run ./x86/msr.flat
 
+The exit status of the binary (and the script) is inconsistent: with
+qemu-system, after the unittest is done, the exit status of qemu is 1,
+different from the 'old style' qemu-kvm, whose exit status in successful
+completion is 0.
 
 Directory structure:
 .:  Makefile and config files for the tests

x86-run

+#!/usr/bin/bash
+
+qemukvm="${QEMU:-qemu-kvm}"
+qemusystem="${QEMU:-qemu-system-x86_64}"
+if
+	${qemukvm} -device '?' 2>&1 | fgrep -e \"testdev\" -e \"pc-testdev\" > /dev/null;
+then
+	qemu="${qemukvm}"
+else
+	if
+		${qemsystem} -device '?' 2>&1 | fgrep -e \"testdev\" -e \"pc-testdev\" > /dev/null;
+	then
+		qemu="${qemusystem}"
+	else
+		echo QEMU binary ${QEMU} has no support for test device. Exiting.
+		exit 1
+	fi
+fi
+
+if
+	${qemu} -device '?' 2>&1 | fgrep "pc-testdev" > /dev/null;
+then
+	command="${qemu} -enable-kvm -device pc-testdev -serial stdio -device isa-debug-exit,iobase=0xf4,iosize=0x4 -kernel"
+else
+	command="${qemu} -device testdev,chardev=testlog -chardev file,id=testlog,path=msr.out -serial stdio -kernel"
+fi
+exec ${command} "$@"