Modify and document new AHCI multi-device support

Get rid of ahci_multi_device="yes" and replace with
ahci_device_limit="X", where X is between 2-32. This allows
users to control the number of devices that will be put on
a single controller. If set to 1 (the default), we use the
original bhyve syntax.

lib/vm-run

@@ -333,23 +333,28 @@ vm::bhyve_device_basic(){
 # step through all functions and just keep going
 #
 # since r302459 the ahci controller supports
-# up to 32 devices per controller. if ahci_multi_device="yes"
+# up to 32 devices per controller. by default we set
-# we make use of this rather than having one controller per disk
+# the device limit to 1 and use the original syntax, but
-#
+# this can be overridden by setting the ahci_device_limit
-# at the moment we only put 8 devices per controller
+# guest option to an integer between 2 and 32.
 #
 # @modifies _devices _slot
 #
 vm::bhyve_device_disks(){
     local _disk _type _dev _path _opts _ahci _atype
     local _ahci_num=0 _num=0 _add _ahci_multi
-    local _ahci_limit=8
+    local _ahci_limit=1
 
-    # check if we want multiple ahci devices per controller
+    # check if user has set a per-controller device limit
-    config::get "_ahci_multi" "ahci_multi_device"
+    config::get "_ahci_multi" "ahci_device_limit"
 
-    if ! util::checkyesno "${_ahci_multi}" || [ ${VERSION_BSD} -lt 1200000 ]; then
+    if [ -n "${_ahci_multi}" -a ${VERSION_BSD} -ge 1200000 ]; then
-        _ahci_multi=""
+
+        # see if it's numeric
+        echo "${_ahci_multi}" | egrep -iqs '^[0-9]+$'
+
+        [ $? -eq 0 -a ${_ahci_multi} -gt 1 -a ${_ahci_multi} -le 32 ] && \
+            _ahci_limit="${_ahci_multi}"
     fi
 
     # get all disks
@@ -369,7 +374,7 @@ vm::bhyve_device_disks(){
         vm::get_disk_path "_path" "${_name}" "${_disk}" "${_dev}"
 
         # ahci device and multi mode?
-        if [ -n "${_ahci_multi}" -a "${_type%%-*}" = "ahci" ]; then
+        if [ ${_ahci_limit} -gt 1 -a "${_type%%-*}" = "ahci" ]; then
 
             # check device type
             case "${_type}" in

sample-templates/config.sample

@@ -102,11 +102,22 @@ debug=""
 #
 uuid=""
 
+# ahci_device_limit
+# By default all ahci devices (ahci-hd/ahci-cd) are configured on independent
+# slots with their own controller. In FreeBSD 12 it's possible to put up
+# to 32 devices on each controller. This setting allows you to configure
+# the number of devices vm-bhyve will allocate on each controller.
+#
+# Valid Options: 2-32
+# Default: 1
+#
+ahci_device_limit="8"
+
 # disk0_type (required)
 # This specifies the emulation type for disk0. Please note that each disk requires
 # at least a type and name.
 #
-# Valid Options: virtio-blk,ahci-hd
+# Valid Options: virtio-blk,ahci-hd,ahci-cd
 #
 disk0_type="virtio-blk"
 

vm

@@ -25,7 +25,7 @@
 # POSSIBILITY OF SUCH DAMAGE.
 
 VERSION=1.2-alpha
-VERSION_INT=102002
+VERSION_INT=102003
 VERSION_BSD=$(uname -K)
 PATH=${PATH}:/bin:/usr/bin:/usr/local/bin:/sbin:/usr/sbin:/usr/local/sbin
 

vm.8

@@ -1,4 +1,4 @@
-.Dd July 8, 2016
+.Dd July 12, 2016
 .Dt VM-BHYVE 8
 .Os
 .Sh NAME
@@ -873,9 +873,10 @@ will generate a mac address.
 .It disk0_type
 The emulation type for the first virtual disk. At least one virtual disk is required.
 Valid options for this are currently
-.Sy virtio-blk
+.Sy virtio-blk ,
+.Sy ahci-hd
 and
-.Sy ahci-hd .
+.Sy ahci-cd .
 Additional disks can be added by adding additional
 .Sy diskX_type
 and
@@ -929,6 +930,14 @@ command line option.
 .Pp
 NOTE: This setting is only supported in templates. It has no function in
 real guest configuration, and is not copied over when a new machine is provisioned
+.It ahci_device_limit
+By default, all AHCI devices are added on their own controller in a unqiue slot/function.
+In FreeBSD 12 it is possible to put up to 32 devices on one controller. This setting
+allows you to control the number of devices (ahci-hd/ahci-cd) that vm-bhyve will
+put on a single controller. The default is
+.Sy 1
+and allowed values are
+.Sy 2-32 .
 .It uuid
 This option allows you to specify a fixed UUID for the guests SMBIOS. Normally, the
 UUID is generated by