Merge pull request #26 from IsaacWoods/next

Add entries for Pebble, acpi, and pci_types for September 2020

Author: phil-opp

content/this-month/2020-09.md

@@ -6,6 +6,7 @@ date = 0000-01-01
 month = "September 2020"
 authors = [
     "phil-opp",
+    "IsaacWoods",
     # add yourself here
 ]
 +++
@@ -36,6 +37,36 @@ The `x86_64` crate provides various abstractions for `x86_64` systems, including
 
 In September, …
 
+### [`acpi`](https://github.com/rust-osdev/acpi)
+<span class="gray">(Section written by [@IsaacWoods](https://github.com/IsaacWoods))</span>
+The `acpi` repository contains crates for parsing the ACPI tables – data structures that the firmware of modern computers use to relay information about the hardware to the OS. Lots of work happened this month:
+
+* [Support](https://github.com/rust-osdev/acpi/pull/76) for the `Fixed Memory`, `Word Address Space`, `DWord Address Space`, `QWord Address Space`, `IRQ Format`,
+  `DMA Format`, and `I/O Port Descriptor` resource descriptors were added. These appear in `_CRS` objects - objects
+  that describe the resources allocated to a particular hardware device. This should be enough support to parse the
+  `_CRS` objects of all devices supported by QEMU. Thanks to [`@michaelmelanson`](https://github.com/michaelmelanson) for his contribution!
+* [Version `2.0.0` of the `acpi` crate was published](https://github.com/rust-osdev/acpi/pull/75), after [consultation with contributors to the Redox project](https://github.com/rust-osdev/acpi/issues/74).
+  This splits the library into two parts - discovering ACPI tables using various methods, and separately, parsing them to discover information about the system.
+  This provides much more flexibility in how tables are parsed, allows support for OS-specific tables, and is
+  important to the Redox project as it allows parsing of the ACPI tables in userspace. We also used this
+  opportunity for breaking changes to clean up a few parts of the library, especially in making our method of
+  mapping physical memory ranges safer.
+* A new crate, [rsdp](https://crates.io/crates/rsdp), was split out from `acpi`. This new crate provides methods
+  for searching for the first ACPI table (the Root System Description Pointer (RSDP)) on BIOS systems without
+  `alloc` support. This makes it suitable for use from bootloaders and similar applications where heap allocation
+  is not supported. All types are reexported by the `acpi` crate, so users can access the same functionality from
+  the main library.
+
+### [`pci_types`](https://github.com/rust-osdev/pci_types)
+<span class="gray">(Section written by [@IsaacWoods](https://github.com/IsaacWoods))</span>
+`pci_types` is a new library in the Rust OSDev organisation that provides types for accessing and configuring PCI
+devices from Rust operating systems. Lots of this code (e.g. identifying devices by class codes) can be shared
+between projects, and would benefit from community contributions. This month, work started on some types for
+representing PCIe addresses, the layout of the configuration space for *endpoints*, device types, and a trait that
+allows the library to access the PCIe configuration space in whichever way the platform exposes it.
+
+Thanks to [@toku-sa-n](https://github.com/toku-sa-n) for their [contribution](https://github.com/rust-osdev/pci_types/pull/1)!
+
 ## Personal Projects
 
 In this section, we describe updates to personal projects that are not directly related to the `rust-osdev` organization. Feel free to [create a pull request](https://github.com/rust-osdev/homepage/pulls) with the updates of your OS project for the next post.
@@ -46,6 +77,34 @@ In this section, we describe updates to personal projects that are not directly
 
 This month, ...
 
+### [`IsaacWoods/pebble`](https://github.com/IsaacWoods/pebble)
+<span class="gray">(Section written by [@IsaacWoods](https://github.com/IsaacWoods))</span>
+
+A fairly large amount of progress has been made on Pebble over the last two months, and a prototype of Pebble's
+defining feature (easy message passing between tasks) is now working!
+
+* The first, basic, version of Pebble's wire format, [ptah](https://github.com/IsaacWoods/pebble/tree/master/lib/ptah) has been completed.
+  This first version is implemented as a Serde format, but libraries could be written for any language that can
+  manipulate a byte stream.
+* Two system calls, `send_message` and `get_message`, were added that allows a message (a series of bytes, and
+  optionally a number of *handles* (effectively, permission to access a certain *kernel object*)) to be sent
+  down a *channel*, between two tasks.
+* Infrastructure for another of Pebble's key features, *services*, was added. This allows userspace tasks to
+  advertise their ability to provide some kind of 'service' to other tasks. A task called [`echo`](https://github.com/IsaacWoods/pebble/blob/master/user/echo/src/main.rs)
+  was built to test this - it provides a service that simply echos any messages sent down it back to the sending
+  task.
+* Work started on the Platform Bus, a concept inspired by another hobby OS [managarm's `mbus`](https://github.com/managarm/managarm/blob/master/docs/src/design/mbus/index.md).
+  All hardware devices on the platform will be added to the Platform Bus by *Bus Drivers*, and described using *properties* (as an
+  example, a PCI device will have properties such as `pci.vendor_id`, and `pci.class`). *Device drivers* will be
+  able to apply to manage devices by sending a *Filter* to the Platform Bus, which specifies which devices they are
+  able to handle, based on a device's properties. In the future, Platform Bus will be responsible for handling all
+  PCI, USB, and hardwired devices on all platforms.
+* The first *Bus Driver* was added to manage PCI devices. It uses a new system call, `pci_get_info`, to get the raw
+  information about PCI from the kernel, and then creates a Platform Bus device for each function, with the correct
+  properties. It uses the new `pci_types` library in the Rust OSDev organisation to identify each device (in the
+  future, this will be extended to know about specific vendor+device ID combinations, to identify specific devices
+  such as a particular graphics card).
+
 ### [`andre-richter/qemu-exit`](https://github.com/andre-richter/qemu-exit)
 
 Version `1.0.x` of the crate has been released!