docs: create config/, devel/ and spin/ subdirectories

Developer documentation should be its own manual.  As a start, move all
developer-oriented files to a separate directory.

Also move non-text files to their own directories: docs/config/ for
QEMU -readconfig input, and docs/spin/ for formal models to be used
with the SPIN model checker.

Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

docs/config/q35-virtio-serial.cfg

@@ -0,0 +1,193 @@
+# q35 - VirtIO guest (serial console)
+# =========================================================
+#
+# Usage:
+#
+#   $ qemu-system-x86_64 \
+#     -nodefaults \
+#     -readconfig q35-virtio-serial.cfg \
+#     -display none -serial mon:stdio
+#
+# You will probably need to tweak the lines marked as
+# CHANGE ME before being able to use this configuration!
+#
+# The guest will have a selection of VirtIO devices
+# tailored towards optimal performance with modern guests,
+# and will be accessed through the serial console.
+#
+# ---------------------------------------------------------
+#
+# Using -nodefaults is required to have full control over
+# the virtual hardware: when it's specified, QEMU will
+# populate the board with only the builtin peripherals
+# plus a small selection of core PCI devices and
+# controllers; the user will then have to explicitly add
+# further devices.
+#
+# The core PCI devices show up in the guest as:
+#
+#   00:00.0 Host bridge
+#   00:1f.0 ISA bridge / LPC
+#   00:1f.2 SATA (AHCI) controller
+#   00:1f.3 SMBus controller
+#
+# This configuration file adds a number of other useful
+# devices, more specifically:
+#
+#   00.1c.* PCI bridge (PCI Express Root Ports)
+#   01:00.0 SCSI storage controller
+#   02:00.0 Ethernet controller
+#
+# More information about these devices is available below.
+#
+# We use '-display none' to prevent QEMU from creating a
+# graphical display window, which would serve no use in
+# this specific configuration, and '-serial mon:stdio' to
+# multiplex the guest's serial console and the QEMU monitor
+# to the host's stdio; use 'Ctrl+A h' to learn how to
+# switch between the two and more.
+
+
+# Machine options
+# =========================================================
+#
+# We use the q35 machine type and enable KVM acceleration
+# for better performance.
+#
+# Using less than 1 GiB of memory is probably not going to
+# yield good performance in the guest, and might even lead
+# to obscure boot issues in some cases.
+
+[machine]
+  type = "q35"
+  accel = "kvm"
+
+[memory]
+  size = "1024"
+
+
+# PCI bridge (PCI Express Root Ports)
+# =========================================================
+#
+# We create eight PCI Express Root Ports, and we plug them
+# all into separate functions of the same slot. Some of
+# them will be used by devices, the rest will remain
+# available for hotplug.
+
+[device "pcie.1"]
+  driver = "pcie-root-port"
+  bus = "pcie.0"
+  addr = "1c.0"
+  port = "1"
+  chassis = "1"
+  multifunction = "on"
+
+[device "pcie.2"]
+  driver = "pcie-root-port"
+  bus = "pcie.0"
+  addr = "1c.1"
+  port = "2"
+  chassis = "2"
+
+[device "pcie.3"]
+  driver = "pcie-root-port"
+  bus = "pcie.0"
+  addr = "1c.2"
+  port = "3"
+  chassis = "3"
+
+[device "pcie.4"]
+  driver = "pcie-root-port"
+  bus = "pcie.0"
+  addr = "1c.3"
+  port = "4"
+  chassis = "4"
+
+[device "pcie.5"]
+  driver = "pcie-root-port"
+  bus = "pcie.0"
+  addr = "1c.4"
+  port = "5"
+  chassis = "5"
+
+[device "pcie.6"]
+  driver = "pcie-root-port"
+  bus = "pcie.0"
+  addr = "1c.5"
+  port = "6"
+  chassis = "6"
+
+[device "pcie.7"]
+  driver = "pcie-root-port"
+  bus = "pcie.0"
+  addr = "1c.6"
+  port = "7"
+  chassis = "7"
+
+[device "pcie.8"]
+  driver = "pcie-root-port"
+  bus = "pcie.0"
+  addr = "1c.7"
+  port = "8"
+  chassis = "8"
+
+
+# SCSI storage controller (and storage)
+# =========================================================
+#
+# We use virtio-scsi here so that we can (hot)plug a large
+# number of disks without running into issues; a SCSI disk,
+# backed by a qcow2 disk image on the host's filesystem, is
+# attached to it.
+#
+# We also create an optical disk, mostly for installation
+# purposes: once the guest OS has been succesfully
+# installed, the guest will no longer boot from optical
+# media. If you don't want, or no longer want, to have an
+# optical disk in the guest you can safely comment out
+# all relevant sections below.
+
+[device "scsi"]
+  driver = "virtio-scsi-pci"
+  bus = "pcie.1"
+  addr = "00.0"
+
+[device "scsi-disk"]
+  driver = "scsi-hd"
+  bus = "scsi.0"
+  drive = "disk"
+  bootindex = "1"
+
+[drive "disk"]
+  file = "guest.qcow2"                          # CHANGE ME
+  format = "qcow2"
+  if = "none"
+
+[device "scsi-optical-disk"]
+  driver = "scsi-cd"
+  bus = "scsi.0"
+  drive = "optical-disk"
+  bootindex = "2"
+
+[drive "optical-disk"]
+  file = "install.iso"                          # CHANGE ME
+  format = "raw"
+  if = "none"
+
+
+# Ethernet controller
+# =========================================================
+#
+# We use virtio-net for improved performance over emulated
+# hardware; on the host side, we take advantage of user
+# networking so that the QEMU process doesn't require any
+# additional privileges.
+
+[netdev "hostnet"]
+  type = "user"
+
+[device "net"]
+  driver = "virtio-net-pci"
+  netdev = "hostnet"
+  bus = "pcie.2"
+  addr = "00.0"