dev: Leave last byte in strncpy for NULL

The length of the strncpy should be one less than the destination to
ensure that there is space for the last NULL byte in case the source
is longer than the destination.

Change-Id: Iea65fa6327c8242bd8ddf4bf9a5a2b5164996495
Signed-off-by: Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com>
Reviewed-on: https://gem5-review.googlesource.com/8561
Reviewed-by: Gabe Black <gabeblack@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

dev, virtio: Improvements to diod process handling

* When dispatching multiple gem5 simulations at once, they race
for the socket id, resulting in a panic when calling 'bind'. To
avoid this problem, the socket id is now created before the diod
process is created. In case of a race, a panic is called in the
gem5 process, whereas before the panic was called in the diod
process where it didn't have any effect.

* In some cases killing the diod process in terminateDiod() using
only SIGTERM failed, so a call using SIGKILL is added.

Change-Id: Ie10741e10af52c8d255210cd4bfe0e5d761485d3
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Sascha Bischoff <sascha.bischoff@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2821
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

dev, virtio: Use of Unix socket for virtIO 9P device

This commit adds support for diod to use a unix socket, rather
than a TCP port. We don't rely on the IP-based connection as we
directly use pipes to interact with diod. This allows it to work
on any system, even if the specific port is taken by another diod
instance (or similar). Secondly, the Unix socket could in theory
be used to debug. However, this functionality has not been
tested.

Change-Id: I616e0ad8768da1dfc867de3af98cdfbb22a72d63
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Sascha Bischoff <sascha.bischoff@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2820
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

style: [patch 1/22] use /r/3648/ to reorganize includes

dev: Add basic checkpoint support to VirtIO9PProxy device

This patch adds very basic checkpoint support for the VirtIO9PProxy
device. Previously, attempts to checkpoint gem5 with a present 9P
device caused gem5 to fatal as none of the state is tracked. We still
do not track any state, but we replace the fatal with a warning which
is triggered if the device has been used by the guest system. In the
event that it has not been used, we assume that no state is lost
during checkpointing. The warning is triggered on both a serialize and
an unserialize to ensure maximum visibility for the user.

sim: Refactor the serialization base class

Objects that are can be serialized are supposed to inherit from the
Serializable class. This class is meant to provide a unified API for
such objects. However, so far it has mainly been used by SimObjects
due to some fundamental design limitations. This changeset redesigns
to the serialization interface to make it more generic and hide the
underlying checkpoint storage. Specifically:

* Add a set of APIs to serialize into a subsection of the current
object. Previously, objects that needed this functionality would
use ad-hoc solutions using nameOut() and section name
generation. In the new world, an object that implements the
interface has the methods serializeSection() and
unserializeSection() that serialize into a named /subsection/ of
the current object. Calling serialize() serializes an object into
the current section.

* Move the name() method from Serializable to SimObject as it is no
longer needed for serialization. The fully qualified section name
is generated by the main serialization code on the fly as objects
serialize sub-objects.

* Add a scoped ScopedCheckpointSection helper class. Some objects
need to serialize data structures, that are not deriving from
Serializable, into subsections. Previously, this was done using
nameOut() and manual section name generation. To simplify this,
this changeset introduces a ScopedCheckpointSection() helper
class. When this class is instantiated, it adds a new /subsection/
and subsequent serialization calls during the lifetime of this
helper class happen inside this section (or a subsection in case
of nested sections).

* The serialize() call is now const which prevents accidental state
manipulation during serialization. Objects that rely on modifying
state can use the serializeOld() call instead. The default
implementation simply calls serialize(). Note: The old-style calls
need to be explicitly called using the
serializeOld()/serializeSectionOld() style APIs. These are used by
default when serializing SimObjects.

* Both the input and output checkpoints now use their own named
types. This hides underlying checkpoint implementation from
objects that need checkpointing and makes it easier to change the
underlying checkpoint storage code.

misc: Another round of static analysis fixups

Mostly addressing uninitialised members.

dev: Add support for 9p proxying over VirtIO

This patch adds support for 9p filesystem proxying over VirtIO. It can
currently operate by connecting to a 9p server over a socket
(VirtIO9PSocket) or by starting the diod 9p server and connecting over
pipe (VirtIO9PDiod).


*WARNING*: Checkpoints are currently not supported for systems with 9p
proxies!