Every system should have some sort of main system bus,
so sysbus_get_default should always return a valid bus.
Without this patch, at least mipssim and malta no longer
start but raise a null pointer access exception (caused by
commit ec990eb622).
Cc: Anthony Liguori <anthony@codemonkey.ws>
Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
If bootindex is specified on command line a string that describes device
in firmware readable way is added into sorted list. Later this list will
be passed into firmware to control boot order.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Introduce a helper function which triggers reset from a given device.
Will be used by pci bus emulation.
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
and make it called via qbus_reset_all().
The qbus reset callback will be used by pci bus reset.
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This patch changes the reset handling so that qdev has no knowledge of the
global system reset. Instead, a new bus/device level function is introduced
that allows all devices/buses on the bus/device to be reset using a depth
first transversal.
N.B. we have to expose the implicit system bus because we have various hacks
that result in an implicit system bus existing. Instead, we ought to have an
explicitly created system bus that we can trigger reset from. That's a topic
for a future patch though.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
There are some cases where you want to walk the busses, in particular, when
searching for a bus either by name or DeviceInfo.
Paolo suggested that we model the return values on how GCC's walkers work which
allows an actor to skip child transversal, or terminate walking with a positive
value that's returned as the qbus_walk_children's result.
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Changing block.h or blockdev.h resulted in recompiling most objects.
Move DriveInfo typedef and BlockInterfaceType enum definitions
to qemu-common.h and rearrange blockdev.h use to decrease churn.
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Switch tree to lookup-by-name using qemu_find_opts().
Also hook up virtfs options so qemu_find_opts works for them too.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
When available, we'd like to be able to access the DeviceState
when registering a savevm. For buses with a get_dev_path()
function, this will allow us to create more unique savevm
id strings.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Some of the failures are internal errors, and hw_error() is okay then.
But the common way to fail is bad user input, e.g. -global
isa-fdc.driveA=foo where drive foo has an unsupported rerror value.
exit(1) instead.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
BusState::name is allocated in qbus_create_inplace().
So it should be freed by qbus_free().
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
parse_string() qemu_strdup()s the property value. It is never freed.
It needs to be freed along with the device. Otherwise, the value of
scsi-disk property "ver" gets leaked when hot-unplugging the disk, for
instance.
Call new PropertyInfo method free() from qdev_free(). Implement it
for qdev_prop_string.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Previous commit added QMP documentation to the qemu-monitor.hx
file, it's is a copy of this information.
While it's good to keep it near code, maintaining two copies of
the same information is too hard and has little benefit as we
don't expect client writers to consult the code to find how to
use a QMP command.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Some legacy users (mostly PC devices) of vmstate_register manage
instance IDs on their own, and that unfortunately in a way that is
incompatible with automatically generated ones. This so far prevents
switching those users to vmstates that are registered by qdev.
To establish a migration path, this patch introduces the concept of
alias IDs. They can be passed to an extended vmstate registration
service, and qdev provides a set service to be used during device init.
find_se will consider the alias in addition to the default ID. We can
then start generating the default ID automatically and writing it on
vmsave, thus converting that format without breaking support for upward
migration.
The user is required specify the highest vmstate version for which the
alias is required. Once this version falls behind the minimum required
for a specific vmstate, an assertion triggers to motivate cleaning up
the obsolete alias.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Note: our device unplug methods don't need conversion work, because
they can't currently fail.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
We sometimes permit omitting the first option name, for example
-device foo is short for -device driver=foo. The name to use
("driver" in the example) is passed as argument to qemu_opts_parse().
For each QemuOptsList, we use at most one such name.
Move the name into QemuOptsList, and pass whether to permit the
abbreviation. This ensures continued consistency, and simplifies the
commit after next in this series.
This reverts commit 3ced9f7a36.
The next commit will convert all of qdev_device_add() to QError, and
it'll be clearer with this partial conversion reverted.
Users can't set them, so qdev_device_help() shouldn't list them. Fix
that. Also make qdev_prop_parse() hide them instead of printing a
meaningless "has no parser" error message.
Their value means nothing to users, so qdev_print_props() shouldn't
print it. Fix by removing their print method.
Their only use is dirty hacks. Document that.
Users can't create them, so qdev_device_help() shouldn't list them.
Fix that.
Also make qdev_device_add() pretend they don't exist. Before, it
rejected them with a "can't be added via command line" message, which
wasn't quite right for monitor command device_add.
error_report() terminates the message with a newline. Strip it it
from its arguments.
This fixes a few error messages lacking a newline:
net_handle_fd_param()'s "No file descriptor named %s found", and
tap_open()'s "vnet_hdr=1 requested, but no kernel support for
IFF_VNET_HDR available" (all three versions).
There's one place that passes arguments without newlines
intentionally: load_vmstate(). Fix it up.
qbus_find() adds an informational line to error messages, and prints
both lines with one qemu_error(). Use error_printf() for the
informational line instead.
While there, simplify: instead of printing buffers filled by
qbus_list_bus() and qbus_list_dev() in one go, make them print it.
qdev_device_help() prints device information with qemu_error(). A
later commit will make qemu_error() print additional stuff that is
only appropriate for proper errors, and then this will break. Use
error_printf() instead.
While there, simplify: instead of printing a buffer filled by
qdev_print_devinfo() in one go, make qdev_print_devinfo() print it.
net.c used a constant to signify no MSI vectors were specified. Extend
that to all qdev devices.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reported-by: "Michael S. Tsirkin" <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
If the device can't be created, don't leak the QemuOpts and release the id of
the device that should have been added by the failed device_add.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This provides the same information as reverted commit 2ba6edf0. Not
much, just better than nothing.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Option "-device DRIVER,?" and monitor command "device_add DRIVER,?"
print the supported properties instead of creating a device. The
former also terminates the program.
This is commit 2ba6edf0 (just reverted) done right.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Help was shoehorned into device creation, qdev_device_add(). Since
help doesn't create a device, it returns NULL, which looks to callers
just like failed device creation. Monitor handler do_device_add()
doesn't care, but main() exits unsuccessfully.
Move help out of device creation, into new qdev_device_help().
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit converts the virtio-console device to create a new
virtio-serial bus that can host console and generic serial ports. The
file hosting this code is now called virtio-serial-bus.c.
The virtio console is now a very simple qdev device that sits on the
virtio-serial-bus and communicates between the bus and qemu's chardevs.
This commit also includes a few changes to the virtio backing code for
pci and s390 to spawn the virtio-serial bus.
As a result of the qdev conversion, we get rid of a lot of legacy code.
The old-style way of instantiating a virtio console using
-virtioconsole ...
is maintained, but the new, preferred way is to use
-device virtio-serial -device virtconsole,chardev=...
With this commit, multiple devices as well as multiple ports with a
single device can be supported.
For multiple ports support, each port gets an IO vq pair. Since the
guest needs to know in advance how many vqs a particular device will
need, we have to set this number as a property of the virtio-serial
device and also as a config option.
In addition, we also spawn a pair of control IO vqs. This is an internal
channel meant for guest-host communication for things like port
open/close, sending port properties over to the guest, etc.
This commit is a part of a series of other commits to get the full
implementation of multiport support. Future commits will add other
support as well as ride on the savevm version that we bump up here.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This patch renames the compat properties into global properties and
makes them more generic. The compatibility stuff is only one of
multiple possible users now.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Please, note that we will lose the "Try -device '?' for a list"
hint as it's qdev specific.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
A bus may have hotplugging enabled but not have the 'unplug'
callback defined, which would lead to a crash on trying to
unplug a device on the bus.
Fix by introducing an assert to check if the callback is valid.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This patchs adds infrastructure to handle -usbdevice via qdev callbacks.
USBDeviceInfo gets a name field (for the -usbdevice driver name) and a
callback for -usbdevice parameter parsing.
The new usbdevice_create() function walks the qdev driver list and looks
for a usb driver with a matching name. When a parameter parsing
callback is present it is called, otherwise the device is created via
usb_create_simple().
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Add a new type for properties common to all nics.
Add helper functions and macros to deal with it.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Introduce a 'peer' member to VLANClientState as an alternative
to a vlan. The idea being that packets are transfered directly
from peer clients rather than going through a vlan.
Patchworks-ID: 35516
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Some callers test for != 0, some for < 0. Normalize to < 0.
Patchworks-ID: 35171
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Like qdev_init(), but terminate program via hw_error() instead of
returning an error value.
Use it instead of qdev_init() where terminating the program on failure
is okay, either because it's during machine construction, or because
we know that failure can't happen.
Because relying in the latter is somewhat unclean, and the former is
not always obvious, it would be nice to go back to qdev_init() in the
not-so-obvious cases, only with proper error handling. I'm leaving
that for another day, because it involves making sure that error
values are properly checked by all callers.
Patchworks-ID: 35168
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Before, every caller had to do this. Only two actually did.
Patchworks-ID: 35170
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Move comment back next to main_system_bus to avoid confusion.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
When initialising a device fails, show the name of the failing device.
The current behaviour is to silently exit on such errors.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Add type safety to qdev reset handlers, by declaring them as
DeviceState * rather than void *.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Adds device_add and device_del commands. device_add accepts accepts
the same syntax like the -device command line switch. device_del
expects a device id. So you should tag your devices with ids if you
want to remove them later on, like this:
device_add pci-ohci,id=ohci
device_del ohci
Unplugging via pci_del or usb_del works too.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This adds a exit callback for device destruction to DeviceInfo, so
we can hook cleanups into qdev device destruction.
Followup patches will put that into use.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Two bug fixes:
* When freeing a device we unregister even stuff we didn't register in
the first place because the ->init() callback failed.
* When freeing a device with child busses attached, we fail to zap the
child bus (and the devices attached to it).
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Replace:
if (-1 == foo())
with:
if (foo() == -1)
While this coding style is not in direct contravention of our currently
ratified CODING_STYLE treaty, it could be argued that the Article 3 of
the European Convention on Human Rights (prohibiting torture and "inhuman
or degrading treatment") reads on the matter.
[This commit message was brought to you without humour, as is evidenced
by the absence of any emoticons]
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Problem: Our file sys-queue.h is a copy of the BSD file, but there are
some additions and it's not entirely compatible. Because of that, there have
been conflicts with system headers on BSD systems. Some hacks have been
introduced in the commits 15cc923584,
f40d753718,
96555a96d7 and
3990d09adf but the fixes were fragile.
Solution: Avoid the conflict entirely by renaming the functions and the
file. Revert the previous hacks.
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Sorry folks, but it has to be. One more of these invasive qdev patches.
We have a serious design bug in the qdev interface: device init
callbacks can't signal failure because the init() callback has no
return value. This patch fixes it.
We have already one case in-tree where this is needed:
Try -device virtio-blk-pci (without drive= specified) and watch qemu
segfault. This patch fixes it.
With usb+scsi being converted to qdev we'll get more devices where the
init callback can fail for various reasons.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
snprintf returns number of bytes needed for the output, not the number
of bytes actually written. Thus the math is wrong ...
Spotted by Markus Armbruster.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Message-Id:
Make -device switch use the QemuOpts framework.
Everything should continue to work like it did before.
New: "-set device.$id.$property=$value" works.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Message-Id:
Use qemu_tolower() instead of tolower().
Fixes warning on NetBSD.
Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Message-Id:
First step cleaning up the drives handling. This one does nothing but
removing drives_table[], still it became seriously big.
drive_get_index() is gone and is replaced by drives_get() which hands
out DriveInfo pointers instead of a table index. This needs adaption in
*tons* of places all over.
The drives are now maintained as linked list.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This patch implements a parser and qdev tree walker for bus paths and
adds qdev_device_add on top of this.
A bus path can be:
(1) full path, i.e. /i440FX-pcihost/pci.0/lsi/scsi.0
(2) bus name, i.e. "scsi.0". Best used together with id= to make
sure this is unique.
(3) relative path starting with a bus name, i.e. "pci.0/lsi/scsi.0"
For the (common) case of a single child bus being attached to a device
it is enougth to specify the device only, i.e. "pci.0/lsi" will be
accepted too.
qdev_device_add() adds devices and accepts bus= parameters to find the
bus the device should be attached to. Without bus= being specified it
takes the first bus it finds where the device can be attached to (i.e.
first pci bus for pci devices, ...).
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Create a default bus name if none is passed to qbus_create().
If the parent device has DeviceState->id set it will be used to create
the bus name,. i.e. -device lsi,id=foo will give you a scsi bus named
"foo.0".
If there is no id BusInfo->name (lowercased) will be used instead, i.e.
-device lsi will give you a scsi bus named "scsi.0".
A scsi adapter with two scsi busses would have "scsi.0" and "scsi.1" or
"$id.0" and "$id.1" busses. The numbers of the child busses are per
device, i.e. when adding two lsi adapters both will have a "*.0" child
bus.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Add id field to DeviceState. Make "info qtree" print it.
This helps users and management apps identifying devices in monitor
output, which is especially useful with otherwise identical devices
such as two virtio disks.
This patch doesn't add a way to set the id, followup patches will do.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
no_user: prevent users from adding certain devices.
desc: description of the device.
alias: to allow user friendly shortcuts on the command line, i.e.
-device usbmouse instead of -device "QEMU USB Mouse" or
-device lsi instead of -device lsi53c895a
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This add support for switching devices into a compatibility mode
using device properties. Machine types can have a list of properties
for specific devices attached to allow the easy creation of machine
types compatible to older qemu versions.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This patch is a major overhaul of the device properties. The properties
are saved directly in the device state struct now, the linked list of
property values is gone.
Advantages:
* We don't have to maintain the list with the property values.
* The value in the property list and the value actually used by
the device can't go out of sync any more (used to happen for
the pci.devfn == -1 case) because there is only one place where
the value is stored.
* A record describing the property is required now, you can't set
random properties any more.
There are bus-specific and device-specific properties. The former
should be used for properties common to all bus drivers. Typical
use case is bus addressing, i.e. pci.devfn and i2c.address.
Properties have a PropertyInfo struct attached with name, size and
function pointers to parse and print properties. A few common property
types have PropertyInfos defined in qdev-properties.c. Drivers are free
to implement their own very special property parsers if needed.
Properties can have default values. If unset they are zero-filled.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
destroy_nic() requires that NICInfo::private by a PCIDevice pointer,
but then goes on to require that the same pointer matches
VLANClientState::opaque.
That is no longer the case for virtio-net since qdev and wasn't
previously the case for rtl8139, ne2k_pci or eepro100.
Make the situation a lot more clear by maintaining a VLANClientState
pointer in NICInfo.
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
The only purpose DeviceType serves is creating a linked list of
DeviceInfo structs. This removes DeviceType and add a next field to
DeviceInfo instead, so the DeviceInfo structs can be changed that way.
Elimitates a pointless extra level of indirection.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
BusInfo is filled with name and size (pretty much like I did for
DeviceInfo as well). There is also a function pointer to print
bus-specific device information to the monitor. sysbus is hooked
up there, I've also added a print function for PCI.
Device creation is slightly modified as well: The device type search
loop now also checks the bus type while scanning the list instead of
complaining thereafter in case of a mismatch. This effectively gives
each bus a private namespace for device names.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Paul Brook <paul@codesourcery.com>
Rationale: move device information from code to data structures.
v2: Adapt the drivers missed in the first version.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
* net-queue: (28 commits)
virtio-net: Increase filter and control limits
virtio-net: Add new RX filter controls
virtio-net: MAC filter optimization
virtio-net: Fix MAC filter overflow handling
virtio-net: reorganize receive_filter()
virtio-net: Use a byte to store RX mode flags
virtio-net: Add version_id 7 placeholder for vnet header support
virtio-net: implement rx packet queueing
net: make use of async packet sending API in tap client
net: add qemu_send_packet_async()
net: split out packet queueing and flushing into separate functions
net: return status from qemu_deliver_packet()
net: add return value to packet receive handler
net: pass VLANClientState* as first arg to receive handlers
net: re-name vc->fd_read() to vc->receive()
net: add fd_readv() handler to qemu_new_vlan_client() args
net: only read from tapfd when we can send
net: vlan clients with no fd_can_read() can always receive
net: move the tap buffer into TAPState
net: factor tap_read_packet() out of tap_send()
...
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
VLANClientState's fd_read() handler doesn't read from file
descriptors, it adds a buffer to the client's receive queue.
Re-name the handlers to make things a little less confusing.
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
This, apparently, is the style we prefer - all VLANClientState
should be an argument to qemu_new_vlan_client().
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Record device property types, and provide a list of properties at device
registration time.
Add a "device" property type that holds a reference to annother device.
Signed-off-by: Paul Brook <paul@codesourcery.com>
We have both IRQ sinks and GPIO inputs. These are in principle exactly
the same thing, so remove the former.
Signed-off-by: Paul Brook <paul@codesourcery.com>
Implement and use a common device bus state. The main side-effect is
that creating a bus and attaching it to a parent device are no longer
separate operations. For legacy code we allow a NULL parent, but that
should go away eventually.
Also tweak creation code to veriry theat a device in on the right bus.
Signed-off-by: Paul Brook <paul@codesourcery.com>
