xen: fix usage of kern_getenv in PVH code

The value returned by kern_getenv should be freed using freeenv.

Reported by:	Coverity
CID:		1248852
Sponsored by: Citrix Systems R&D
xen: allow to register event channels without handlers

This is needed by the event channel user-space device, that requires
registering event channels without unmasking them. intr_add_handler
will unconditionally unmask the event channel, so we avoid calling it
if no filter/handler is provided, and then the user will be in charge
of calling it when ready.

In order to do this, we need to change the opaque type
xen_intr_handle_t to contain the event channel port instead of the
opaque cookie returned by intr_add_handler, since now registration of
event channels without handlers are allowed. The cookie will now be
stored inside of the private xenisrc struct. Also, introduce a new
function called xen_intr_add_handler that allows adding a
filter/handler after the event channel has been registered.

Sponsored by: Citrix Systems R&D

x86/xen/xen_intr.c:
 - Leave the event channel without a handler if no filter/handler is
   provided to xen_intr_bind_isrc.
 - Don't perform an evtchn_mask_port, intr_add_handler will already do
   it.
 - Change the opaque type xen_intr_handle_t to contain a pointer to
   the event channel port number, and make the necessary changes to
   related functions.
 - Introduce a new function called xen_intr_add_handler that can be
   used to add filter/handlers to an event channel after registration.

xen/xen_intr.h:
 - Add prototype of xen_intr_add_handler.
xen: import a proper event channel user-space device

The user-space event channel device is used by applications to receive
and send event channel interrupts. This device is based on the Linux
evtchn device.

Sponsored by: Citrix Systems R&D

xen/evtchn/evtchn_dev.c:
 - Remove the old event channel device, which was already disabled in
   the build system.

dev/xen/evtchn/evtchn_dev.c:
 - Import a new event channel device based on the one present in
   Linux.
 - This device allows the following operations:
   - Bind VIRQ event channels (ioctl).
   - Bind regular event channels (ioctl).
   - Create and bind new event channels (ioctl).
   - Unbind event channels (ioctl).
   - Send notifications to event channels (ioctl).
   - Reset the device shared memory ring (ioctl).
   - Unmask event channels (write).
   - Receive event channel upcalls (read).
 - The new code is MP safe, and can be used concurrently.

conf/files:
 - Add the new device to the build system.
xen: add a Xen to BSD error translation

Since Xen and FreeBSD error codes are completely different add a
translation layer in order to convert Xen error codes into native
FreeBSD error codes. This will be used by the privcmd device, which
needs to return the hypercall errors into user-space.

Sponsored by: Citrix Systems R&D

xen/error.h:
 - Import Xen error codes.
 - Create a table to map Xen error codes into FreeBSD native error
   codes.
 - Create an inline function that performs the translation.
xen: implement the privcmd user-space device

This device is only attached to priviledged domains, and allows the
toolstack to interact with Xen. The two functions of the privcmd
interface is to allow the execution of hypercalls from user-space, and
the mapping of foreign domain memory.

Sponsored by: Citrix Systems R&D

i386/include/xen/hypercall.h:
amd64/include/xen/hypercall.h:
 - Introduce a function to make generic hypercalls into Xen.

xen/interface/xen.h:
xen/interface/memory.h:
 - Import the new hypercall XENMEM_add_to_physmap_range used by
   auto-translated guests to map memory from foreign domains.

dev/xen/privcmd/privcmd.c:
 - This device has the following functions:
   - Allow user-space applications to make hypercalls into Xen.
   - Allow user-space applications to map memory from foreign domains,
     this is accomplished using the newly introduced hypercall
     (XENMEM_add_to_physmap_range).

xen/privcmd.h:
 - Public ioctl interface for the privcmd device.

x86/xen/hvm.c:
 - Remove declaration of hypercall_page, now it's declared in
   hypercall.h.

conf/files:
 - Add the privcmd device to the build process.
netback: change xnb naming convention

Current FreeBSD netback names the interface with xnb<device unit>, but
this is not suitable for usage with the Xen toolstack, which expects
something similar to <prefix><domid><handle>. In order to solve this,
change the netback naming convention to use xnb<domid>.<handle>.

Sponsored by: Citrix Systems R&D

dev/xen/netback/netback.c:
 - Change netback to use the nomenclature stated above.
Fix linking static test binaries with atf.test.mk

Check for -static in LDFLAGS or LDFLAGS.<test>, then pass in the appropriate
dependency (LIBATF or LDATF)

This unbreaks the build with some of the NetBSD tests that need to be compiled
statically

Reviewed by: imp, jmmv
Phabric: D991
Sponsored by: EMC / Isilon Storage Division
since we cast a pointer, use the correct signedness
(this was already in, and got lost in a recent update).
cxgbe/iw_cxgbe: wake up waiters after flushing the qp.

Obtained from:	Chelsio
Clip the settings for the NFS rsize, wsize mount options
to a power of 2. For non-power of 2 settings, intermittent
page faults have been reported. Although the bug that causes
these page faults/crashes has not been identified, it does
not appear to occur when rsize, wsize is a power of 2.

Reported by:	tcberner@gmail.com
MFC after:	2 weeks
The NetBSD libc tests use several definitions/macros that aren't available in
FreeBSD

Add the missing compat definitions/macros to lib/libnetbsd so the testcases
can be compiled with libnetbsd without having to invent ad hoc #define's, or
having to convert things over to FreeBSD idioms

Reviewed by: brooks
Phabric: D993
Sponsored by: EMC / Isilon Storage Division
Rename log2 to tal_log2.

Submitted by:	luigi
Revert r273481 so it can be recoded using fls(), which
some feel will make it more readable.