diff --git a/lib/constants.py b/lib/constants.py
index 63807add5ce64c3f47c0fc055230feb2c1745d3b..1222bf9faaf1a89940857b0b08c34c8ffdff90a6 100644
--- a/lib/constants.py
+++ b/lib/constants.py
@@ -580,6 +580,7 @@ HV_VHOST_NET = "vhost_net"
 HV_KVM_USE_CHROOT = "use_chroot"
 HV_CPU_MASK = "cpu_mask"
 HV_MEM_PATH = "mem_path"
+HV_BLOCKDEV_PREFIX = "blockdev_prefix"
 
 HVS_PARAMETER_TYPES = {
   HV_BOOT_ORDER: VTYPE_STRING,
@@ -617,6 +618,7 @@ HVS_PARAMETER_TYPES = {
   HV_KVM_USE_CHROOT: VTYPE_BOOL,
   HV_CPU_MASK: VTYPE_STRING,
   HV_MEM_PATH: VTYPE_STRING,
+  HV_BLOCKDEV_PREFIX: VTYPE_STRING,
   }
 
 HVS_PARAMETERS = frozenset(HVS_PARAMETER_TYPES.keys())
@@ -953,6 +955,7 @@ HVC_DEFAULTS = {
     HV_KERNEL_ARGS: 'ro',
     HV_MIGRATION_PORT: 8002,
     HV_MIGRATION_MODE: HT_MIGRATION_LIVE,
+    HV_BLOCKDEV_PREFIX: "sd",
     },
   HT_XEN_HVM: {
     HV_BOOT_ORDER: "cd",
@@ -968,6 +971,7 @@ HVC_DEFAULTS = {
     HV_MIGRATION_PORT: 8002,
     HV_MIGRATION_MODE: HT_MIGRATION_NONLIVE,
     HV_USE_LOCALTIME: False,
+    HV_BLOCKDEV_PREFIX: "hd",
     },
   HT_KVM: {
     HV_KERNEL_PATH: "/boot/vmlinuz-2.6-kvmU",
diff --git a/lib/hypervisor/hv_xen.py b/lib/hypervisor/hv_xen.py
index bdf38a4d99f9db05fa96f6d299f92d4b5b340d7f..5e39fce58501c3fefabb1ba66cd6977114066800 100644
--- a/lib/hypervisor/hv_xen.py
+++ b/lib/hypervisor/hv_xen.py
@@ -312,7 +312,7 @@ class XenHypervisor(hv_base.BaseHypervisor):
       return "'xm info' failed: %s, %s" % (result.fail_reason, result.output)
 
   @staticmethod
-  def _GetConfigFileDiskData(block_devices):
+  def _GetConfigFileDiskData(block_devices, blockdev_prefix):
     """Get disk directive for xen config file.
 
     This method builds the xen config disk directive according to the
@@ -321,6 +321,8 @@ class XenHypervisor(hv_base.BaseHypervisor):
     @param block_devices: list of tuples (cfdev, rldev):
         - cfdev: dict containing ganeti config disk part
         - rldev: ganeti.bdev.BlockDev object
+    @param blockdev_prefix: a string containing blockdevice prefix,
+                            e.g. "sd" for /dev/sda
 
     @return: string containing disk directive for xen instance config file
 
@@ -333,9 +335,7 @@ class XenHypervisor(hv_base.BaseHypervisor):
     if len(block_devices) > 24:
       # 'z' - 'a' = 24
       raise errors.HypervisorError("Too many disks")
-    # FIXME: instead of this hardcoding here, each of PVM/HVM should
-    # directly export their info (currently HVM will just sed this info)
-    namespace = ["sd" + chr(i + ord('a')) for i in range(24)]
+    namespace = [blockdev_prefix + chr(i + ord('a')) for i in range(24)]
     for sd_name, (cfdev, dev_path) in zip(namespace, block_devices):
       if cfdev.mode == constants.DISK_RDWR:
         mode = "w"
@@ -459,6 +459,8 @@ class XenPvmHypervisor(XenHypervisor):
     constants.HV_KERNEL_ARGS: hv_base.NO_CHECK,
     constants.HV_MIGRATION_PORT: hv_base.NET_PORT_CHECK,
     constants.HV_MIGRATION_MODE: hv_base.MIGRATION_MODE_CHECK,
+    # TODO: Add a check for the blockdev prefix (matching [a-z:] or similar).
+    constants.HV_BLOCKDEV_PREFIX: hv_base.NO_CHECK,
     }
 
   @classmethod
@@ -509,7 +511,8 @@ class XenPvmHypervisor(XenHypervisor):
         nic_str += ", bridge=%s" % nic.nicparams[constants.NIC_LINK]
       vif_data.append("'%s'" % nic_str)
 
-    disk_data = cls._GetConfigFileDiskData(block_devices)
+    disk_data = cls._GetConfigFileDiskData(block_devices,
+                                           hvp[constants.HV_BLOCKDEV_PREFIX])
 
     config.write("vif = [%s]\n" % ",".join(vif_data))
     config.write("disk = [%s]\n" % ",".join(disk_data))
@@ -639,13 +642,10 @@ class XenHvmHypervisor(XenHypervisor):
       vif_data.append("'%s'" % nic_str)
 
     config.write("vif = [%s]\n" % ",".join(vif_data))
-    disk_data = cls._GetConfigFileDiskData(block_devices)
-    disk_type = hvp[constants.HV_DISK_TYPE]
-    if disk_type in (None, constants.HT_DISK_IOEMU):
-      replacement = ",ioemu:hd"
-    else:
-      replacement = ",hd"
-    disk_data = [line.replace(",sd", replacement) for line in disk_data]
+
+    disk_data = cls._GetConfigFileDiskData(block_devices,
+                                           hvp[constants.HV_BLOCKDEV_PREFIX])
+
     iso_path = hvp[constants.HV_CDROM_IMAGE_PATH]
     if iso_path:
       iso = "'file:%s,hdc:cdrom,r'" % iso_path
diff --git a/man/gnt-instance.rst b/man/gnt-instance.rst
index 08b7e0001e850c31c2ddfb28fdced8df35a60c5c..ae5ce466cf4d2ceed4d9d7c448efe93467ee8330 100644
--- a/man/gnt-instance.rst
+++ b/man/gnt-instance.rst
@@ -185,6 +185,13 @@ boot\_order
     interfaces. This has been fixed in more recent versions and is
     confirmed to work at least with qemu-kvm 0.11.1.
 
+blockdev\_prefix
+    Valid for the Xen HVM and PVM hypervisors.
+
+    Relevant to nonpvops guest kernels, in which the disk device names are
+    given by the host.  Allows to specify 'xvd', which helps run Red Hat based
+    installers, driven by anaconda.
+
 cdrom\_image\_path
     Valid for the Xen HVM and KVM hypervisors.