runqemu: do not rely on grepping images

Fixed when the image is large and not enough memory:
  grep: memory exhausted
  Aborted

[YOCTO #11073]

(From OE-Core rev: a99deb30a0138594147ae28aab016fe4b74b8959)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/qemuboot.bbclass

@@ -64,6 +64,9 @@ QB_DEFAULT_FSTYPE ?= "ext4"
 QB_OPT_APPEND ?= "-show-cursor"
 QB_NETWORK_DEVICE ?= "-device virtio-net-pci,netdev=net0,mac=@MAC@"
 
+# This should be kept align with ROOT_VM
+QB_DRIVE_TYPE ?= "/dev/sd"
+
 # Create qemuboot.conf
 addtask do_write_qemuboot_conf after do_rootfs before do_image
 IMGDEPLOYDIR ?= "${WORKDIR}/deploy-${PN}-image-complete"

scripts/runqemu

@@ -980,23 +980,26 @@ class BaseConfig(object):
             self.kernel_cmdline = 'root=/dev/ram0 rw debugshell'
             self.rootfs_options = '-initrd %s' % self.rootfs
         else:
+            vm_drive = ''
             if self.fstype in self.vmtypes:
                 if self.fstype == 'iso':
                     vm_drive = '-cdrom %s' % self.rootfs
-                else:
-                    cmd1 = "grep -q 'root=/dev/sd' %s" % self.rootfs
-                    cmd2 = "grep -q 'root=/dev/hd' %s" % self.rootfs
-                    if subprocess.call(cmd1, shell=True) == 0:
+                elif self.get('QB_DRIVE_TYPE'):
+                    drive_type = self.get('QB_DRIVE_TYPE')
+                    if drive_type.startswith("/dev/sd"):
                         logger.info('Using scsi drive')
                         vm_drive = '-drive if=none,id=hd,file=%s,format=%s -device virtio-scsi-pci,id=scsi -device scsi-hd,drive=hd' \
                                        % (self.rootfs, rootfs_format)
-                    elif subprocess.call(cmd2, shell=True) == 0:
+                    elif drive_type.startswith("/dev/hd"):
                         logger.info('Using ide drive')
                         vm_drive = "%s,format=%s" % (self.rootfs, rootfs_format)
                     else:
-                        logger.warn("Can't detect drive type %s" % self.rootfs)
-                        logger.warn('Trying to use virtio block drive')
-                        vm_drive = '-drive if=virtio,file=%s,format=%s' % (self.rootfs, rootfs_format)
+                        logger.warn("Unknown QB_DRIVE_TYPE: %s" % drive_type)
+
+                if not vm_drive:
+                    logger.warn("Failed to figure out drive type, consider define or fix QB_DRIVE_TYPE")
+                    logger.warn('Trying to use virtio block drive')
+                    vm_drive = '-drive if=virtio,file=%s,format=%s' % (self.rootfs, rootfs_format)
                 self.rootfs_options = '%s -no-reboot' % vm_drive
             self.kernel_cmdline = 'root=%s rw highres=off' % (self.get('QB_KERNEL_ROOT'))