better/safer Linux recommendations

docs/mkdocs/requirements.txt

@@ -1,6 +1,6 @@
 # This requirements file is for python3
-mkdocs == 1.2.3
-mkdocs-material == 7.1.7
-mkdocs-material-extensions == 1.0.1
-pymdown-extensions == 8.2
-mkdocstrings == 0.15.1
+mkdocs == 1.4.0
+mkdocs-material == 8.5.6
+mkdocs-material-extensions == 1.0.3
+pymdown-extensions == 9.6
+mkdocstrings-python == 0.7.1

docs/mkdocs/src/platforms/linux.md

@@ -1,48 +1,86 @@
 :material-linux: LINUX PLATFORM
 ===============================
 
-In addition to all the standard functionality available from the project by running the python tools and/or writing your own apps by leveraging the API, it is also possible on Linux hosts to interface the Bumble stack with the native BlueZ stack, and with Bluetooth controllers.
+Using Bumble With Physical Bluetooth Controllers
+------------------------------------------------
 
-Using Bumble With BlueZ
------------------------
+A Bumble application can interface with a local Bluetooth controller on a Linux host.
+The 3 main types of physical Bluetooth controllers are:
 
-A Bumble virtual controller can be attached to the BlueZ stack.
-Attaching a controller to BlueZ can be done by either simulating a UART HCI interface, or by using the VHCI driver interface if available.
-In both cases, the controller can run locally on the Linux host, or remotely on a different host, with a bridge between the remote controller and the local BlueZ host, which may be useful when the BlueZ stack is running on an embedded system, or a host on which running the Bumble controller is not convenient.
+  * Bluetooth USB Dongle
+  * HCI over  UART (via a serial port)
+  * Kernel-managed Bluetooth HCI (HCI Sockets)
 
-### Using VHCI
+!!! tip "Conflicts with the kernel and BlueZ"
+    If your use a USB dongle that is recognized by your kernel as a supported Bluetooth device, it is
+    likely that the kernel driver will claim that USB device and attach it to the BlueZ stack. 
+    If you want to claim ownership of it to use with Bumble, you will need to set the state of the corresponding HCI interface as `DOWN`. 
+    HCI interfaces are numbered, starting from 0 (i.e `hci0`, `hci1`, ...).
 
-With the [VHCI transport](../transports/vhci.md) you can attach a Bumble virtual controller to the BlueZ stack. Once attached, the controller will appear just like any other controller, and thus can be used with the standard BlueZ tools.
-
-!!! example "Attaching a virtual controller"
-    With the example app `run_controller.py`:
+    For example, to bring `hci0` down:
     ```
-    PYTHONPATH=. python3 examples/run_controller.py F6:F7:F8:F9:FA:FB examples/device1.json vhci
-    ```
-    
-    You should see a 'Virtual Bus' controller. For example:
-    ```
-    $ hciconfig
-    hci0:	Type: Primary  Bus: Virtual
-        BD Address: F6:F7:F8:F9:FA:FB  ACL MTU: 27:64  SCO MTU: 0:0
-        UP RUNNING 
-        RX bytes:0 acl:0 sco:0 events:43 errors:0
-        TX bytes:274 acl:0 sco:0 commands:43 errors:0
+    $ sudo hciconfig hci0 down
     ```
 
-    And scanning for devices should show the virtual 'Bumble' device that's running as part of the `run_controller.py` example app:
+    You can use the `hciconfig` command with no arguments to get a list of HCI interfaces seen by
+    the kernel.
+
+    Also, if `bluetoothd` is running on your system, it will likely re-claim the interface after you
+    close it, so you may need to bring the interface back `UP` before using it again, or to disable
+    `bluetoothd` altogether (see the section further below about BlueZ and `bluetoothd`).
+
+### Using a USB Dongle
+
+See the [USB Transport page](../transports/usb.md) for general information on how to use HCI USB controllers.
+
+!!! tip "USB Permissions"
+    By default, when running as a regular user, you won't have the permission to use
+    arbitrary USB devices.
+    You can change the permissions for a specific USB device based on its bus number and 
+    device number (you can use `lsusb` to find the Bus and Device numbers for your Bluetooth
+    dongle).
+
+    Example:
     ```
-    pi@raspberrypi:~ $ sudo hcitool -i hci2 lescan
-    LE Scan ...
-    F0:F1:F2:F3:F4:F5 Bumble
+    $ sudo chmod o+w /dev/bus/usb/001/004
     ```
+    This will change the permissions for Device 4 on Bus 1.
+
+    Note that the USB Bus number and Device number may change depending on where you plug the USB
+    dongle and what other USB devices and hubs are also plugged in.
+
+    If you need to make the permission changes permanent across reboots, you can create a `udev`
+    rule for your specific Bluetooth dongle. Visit [this Arch Linux Wiki page](https://wiki.archlinux.org/title/udev) for a
+    good overview of how you may do that.
+
+### Using HCI over UART
+
+See the [Serial Transport page](../transports/serial.md) for general information on how to use HCI over a UART (serial port).
 
 ### Using HCI Sockets
 
 HCI sockets provide a way to send/receive HCI packets to/from a Bluetooth controller managed by the kernel.
-The HCI device referenced by an `hci-socket` transport (`hciX`, where `X` is an integer, with `hci0` being the first controller device, and so on) must be in the `DOWN` state before it can be opened as a transport.
-You can bring a HCI controller `UP` or `DOWN` with `hciconfig`.
+See the [HCI Socket Transport page](../transports/hci_socket.md) for details on the `hci-socket` tansport syntax.
 
+The HCI device referenced by an `hci-socket` transport (`hci<X>`, where `<X>` is an integer, with `hci0` being the first controller device, and so on) must be in the `DOWN` state before it can be opened as a transport.
+You can bring a HCI controller `UP` or `DOWN` with `hciconfig hci<X> up` and `hciconfig hci<X> up`.
+
+!!! tip "HCI Socket Permissions"
+    By default, when running as a regular user, you won't have the permission to use
+    an HCI socket to a Bluetooth controller (you may see an exception like `PermissionError: [Errno 1] Operation not permitted`).
+
+    If you want to run without using `sudo`, you need to manage the capabilities by adding the appropriate entries in `/etc/security/capability.conf` to grant a user or group the `cap_net_admin` capability.  
+    See [this manpage](https://manpages.ubuntu.com/manpages/bionic/man5/capability.conf.5.html) for details.
+    
+    Alternatively, if you are just experimenting temporarily, the `capsh` command may be useful in order
+    to execute a single command with enhanced permissions, as in this example:
+
+
+    ```
+    $ sudo capsh --caps="cap_net_admin+eip cap_setpcap,cap_setuid,cap_setgid+ep" --keep=1 --user=$USER --addamb=cap_net_admin  -- -c "<path/to/executable> <executable-args>"
+    ```
+    Where `<path/to/executable>` is the path to your `python3` executable or to one of the Bumble bundled command-line applications.
+    
 !!! tip "List all available controllers"
     The command
     ```
@@ -72,29 +110,16 @@ You can bring a HCI controller `UP` or `DOWN` with `hciconfig`.
     ```
     $ hciconfig hci0 down
     ``` 
-    (or `hciX` with `X` being the index of the controller device you want to use), but a simpler solution is to just stop the `bluetoothd` daemon, with a command like:
+    (or `hci<X>` with `<X>` being the index of the controller device you want to use), but a simpler solution is to just stop the `bluetoothd` daemon, with a command like:
     ```
     $ sudo systemctl stop bluetooth.service
     ```
     You can always re-start the daemon with
     ```
     $ sudo systemctl start bluetooth.service
-    ```
 
-### Using a Simulated UART HCI
-
-### Bridge to a Remote Controller
-
-
-Using Bumble With Bluetooth Controllers
----------------------------------------
-
-A Bumble application can interface with a local Bluetooth controller.
-If your Bluetooth controller is a standard HCI USB controller, see the [USB Transport page](../transports/usb.md) for details on how to use HCI USB controllers.
-If your Bluetooth controller is a standard HCI UART controller, see the [Serial Transport page](../transports/serial.md).
-Alternatively, a Bumble Host object can communicate with one of the platform's controllers via an HCI Socket.
-
-`<details to be filled in>`
+Bumble on the Raspberry Pi
+--------------------------
 
 ### Raspberry Pi 4 :fontawesome-brands-raspberry-pi:
 
@@ -102,9 +127,10 @@ You can use the Bluetooth controller either via the kernel, or directly to the d
 
 #### Via The Kernel
 
-Use an HCI Socket transport
+Use an HCI Socket transport (see section above)
 
 #### Directly
+
 In order to use the Bluetooth controller directly on a Raspberry Pi 4 board, you need to ensure that it isn't being used by the BlueZ stack (which it probably is by default).
 
 ```
@@ -136,3 +162,47 @@ should detach the controller from the stack, after which you can use the HCI UAR
     python3 run_scanner.py serial:/dev/serial1,3000000
     ```
 
+
+Using Bumble With BlueZ
+-----------------------
+
+In addition to all the standard functionality available from the project by running the python tools and/or writing your own apps by leveraging the API, it is also possible on Linux hosts to interface the Bumble stack with the native BlueZ stack, and with Bluetooth controllers.
+
+A Bumble virtual controller can be attached to the BlueZ stack.
+Attaching a controller to BlueZ can be done by either simulating a UART HCI interface, or by using the VHCI driver interface if available.
+In both cases, the controller can run locally on the Linux host, or remotely on a different host, with a bridge between the remote controller and the local BlueZ host, which may be useful when the BlueZ stack is running on an embedded system, or a host on which running the Bumble controller is not convenient.
+
+### Using VHCI
+
+With the [VHCI transport](../transports/vhci.md) you can attach a Bumble virtual controller to the BlueZ stack. Once attached, the controller will appear just like any other controller, and thus can be used with the standard BlueZ tools.
+
+!!! example "Attaching a virtual controller"
+    With the example app `run_controller.py`:
+    ```
+    python3 examples/run_controller.py F6:F7:F8:F9:FA:FB examples/device1.json vhci
+    ```
+    
+    You should see a 'Virtual Bus' controller. For example:
+    ```
+    $ hciconfig
+    hci0:	Type: Primary  Bus: Virtual
+        BD Address: F6:F7:F8:F9:FA:FB  ACL MTU: 27:64  SCO MTU: 0:0
+        UP RUNNING 
+        RX bytes:0 acl:0 sco:0 events:43 errors:0
+        TX bytes:274 acl:0 sco:0 commands:43 errors:0
+    ```
+
+    And scanning for devices should show the virtual 'Bumble' device that's running as part of the `run_controller.py` example app:
+    ```
+    pi@raspberrypi:~ $ sudo hcitool -i hci2 lescan
+    LE Scan ...
+    F0:F1:F2:F3:F4:F5 Bumble
+    ```
+
+    ```
+
+### Using a Simulated UART HCI
+
+### Bridge to a Remote Controller
+
+

setup.cfg

@@ -67,6 +67,6 @@ development =
     invoke >= 1.4
     nox >= 2022
 documentation =
-    mkdocs >= 1.2.3
-    mkdocs-material >= 8.1.9
+    mkdocs >= 1.4.0
+    mkdocs-material >= 8.5.6
     mkdocstrings[python] >= 0.19.0