Add release notes for 0.5.0

Signed-off-by: Ivan Velickovic <i.velickovic@unsw.edu.au>

.reuse/dep5

@@ -3,6 +3,7 @@ Upstream-Name: seL4 Device Driver Framework
 Source: https://github.com/au-ts/sddf
 
 Files:
+    CHANGES.md
     build.zig.zon
     examples/i2c/build.zig.zon
     examples/serial/build.zig.zon

CHANGES.md

@@ -0,0 +1,90 @@
+# Revision history for sDDF
+
+## Release 0.5.0
+
+### General
+
+* Move to Microkit 1.4.0.
+    * Previously a development version of Microkit was used, now we use
+      an official release for everything.
+* Add QEMU support to the timer and echo server examples.
+* Remove dependency on a full libc, all the provided components use our own
+  utility functions now.
+* Transition to a modular 'Makefile snippets' build system structure to
+  simplify the composition of sDDF components.
+* Introduce snippets for the Zig build system, as an alternative to Make.
+    * Instructions for using the Zig build system can be found in each
+      example's README.
+    * No components are solely built with Zig, the primary build system is
+      still Make.
+* Introduce configurable printf logging for debug versus release mode, making
+  it easier to have some components continue logging to the serial in release
+  mode.
+
+### Block
+
+* Move the capacity of the shared queue out of shared memory
+  and into the queue handles. This prevents malicious clients
+  from messing with the queue size and potentially causing the
+  virtualiser or other trusted components to crash/misbehave.
+* Introduce a config header to enable the system designer to have a variable
+  amount of clients, previously it was all hard-coded.
+    * It should be noted that we are working on tooling to automate this process
+      and these configs are likely to significantly change by the next release.
+* Change block virtualiser to use offsets when interfacing with clients and DMA
+  physical addresses when interfacing with the driver.
+    * This makes the block system consistent with the networking system in how it
+      handles client-to-driver address translation.
+* Use 'capacity' instead of size in the shared queue library to avoid confusion.
+
+### I2C
+
+* Use 'capacity' instead of size in the shared queue library to avoid confusion.
+
+### Network
+
+* Add a virtIO network driver.
+    * This allows us to have networking on QEMU making it easier to simulate
+      non-trivial systems.
+* Change RX virtualiser policy for broadcast packets.
+    * Previously all broadcast packets would go to the ARP component, now the
+      default policy is to forward broadcast packets to all clients.
+    * We have only run into this becoming necessary so far when simulating our
+      systems using QEMU since its internal DHCP server sends broadcast packets.
+* Introduce a config header to enable the system designer to have a variable
+  amount of clients, previously it was all hard-coded.
+    * It should be noted that we are working on tooling to automate this process
+      and these configs are likely to significantly change by the next release.
+* Fix caching operations in RX virtualiser, previously this would lead to
+  issues with TCP traffic.
+* Various bug fixes in the Amlogic ethernet driver.
+* Fixes and changes for improved TCP performance.
+
+### Serial
+
+* Redesign the entire sub-system.
+    * The serial device class was previously following
+      the network design which was not an ideal design for serial devices. This new
+      design is intended to be used for character-by-character devices. DMA
+      capable serial devices will have a separate design, more aligned with the design
+      of our other DMA capable devices such as ethernet and block.
+    * Various bugs were fixed and so individual drivers as well as the system
+      as a whole should be more stable.
+* Introduce a config header to enable the system designer to have a variable
+  amount of clients, previously it was all hard-coded.
+    * It should be noted that we are working on tooling to automate this process
+      and these configs are likely to significantly change by the next release.
+
+### Sound
+
+This release adds the initial sound virtualiser and shared queue library.
+
+We do not yet have any native sound drivers.
+
+See the design document for the specification and more information.
+
+### Timer
+
+* Add a driver for the ARM architectural timer (necessary for QEMU on ARM).
+* Various cleanup/refactoring of all the drivers to simplify their implementation
+  and fix bugs.