Add sglist_append_bio(9) to append a struct bio's data to a sglist

Reviewed by:	jhb, kib (long ago)
Add unmapped IO support to virtio_blk(4)
Add unmapped IO support to virtio_scsi(4)
Prevent misc_helpers from running as a test.

Do this by generating misc_helpers explicitly, without using the
ATF_TESTS_SH functionality.

While this script is technically an atf-sh test program, it is not intended
to be run as a test and therefore it mustn't end up in the Kyuafile.  Using
ATF_TESTS_SH means that misc_helpers ended up registered in the Kyuafile
and then failed to run as a test.

The alternative would be to supply an explicit Kyuafile from this directory
that lists the known test files, but doing it the way described above will
be easier to maintain.

MFC after:	3 days
Mark the bin/pax tests as requiring perl.

The effect of this is that the test program is marked as skipped when perl
is missing, instead of marking it as broken due to an execution failure.

MFC after:	3 days
Add new testcase for USB mass storage.
Separate I/O errors from reception of STALL PID.

MFC after:	1 week
Implement better error recovery for Transaction Translators, TTs,
found in High Speed USB HUBs which translate from High Speed USB into
FULL or LOW speed USB. In some rare cases SPLIT transactions might get
lost, which might leave the TT in an unknown state. Whenever we detect
such an error try to issue either a clear TT buffer request, or if
that is not possible reset the whole TT.

MFC after:	1 week
Point the user to dmesg(1) to get informations about why loading a module did fail
instead of printing the cryptic "Exec format error"

MFC after:	1 week
Update the BUGS section according the recent changes in kldload(8)

Reviewed by:	bdrewery
MFC after:	1 week
Fix typo

Reported by:	dumbbell
Fix dmesg(1) -> dmesg(8)

Reported by:	trasz
Re-apply the part of r260022 that was reverted by r260030 with
one significant difference: for LIB32 builds both TARGET_ARCH
and MACHINE_ARCH are defined. TARGET_ARCH confusingly holds the
architecture of the host (e.g. amd64), while MACHINE_ARCH holds
the architecture were trying to build (e.g. i386). With both
set and different, r260022 changed the behaviour to interpret
the condition as building a cross-amd64 libkvm on i386, when
obviously we're trying to build an i386 version on amd64. When
COMPAT_32BIT is defined, we're building LIB32 and ignore the
value of TARGET_ARCH as we did before.
We don't have to worry about page sizes when working on virtual
cores (i.e. minidumps). Every segment is virtually contiguous.
When building a cross-kgdb, suppress the registration of the
standard core target by declaring coreops_suppress_target with
initializer. This is also happening for non-cross kgdb, by
virtue of having fbsd-threads.c in libgdb and having it do the
exact same thing. Since fbsd-threads.c is not included in in
libgdb when building a cross debugger, we ended up with more
than 1 core file targets (the standard gdb core file target and
kgdb's libkvm based core file target) and this behaves the same
as not having a core target at all.
Remove scary comment about this being a test key.

There has been no need to regenerate the signing key.

Reported by:	mat
Approved by:	bapt (mentor)
MFC after:	3 days
The onyx codec works also as module, so add it.

MFC after:	1 month
Described in the man page but not implemented. Here it comes,
atomic_swap_32/64. The latter only for powerpc64.

MFC after:	1 month
Move myself from ports alumni to active ports committer section.
Add an edge indicating mat as my ports mentor.

Approved by:	mat (mentor)
ANSI-fy prototype.

MFC after:	2 weeks