--- wikisrc/ports/evbarm/raspberry_pi.mdwn	2018/10/30 01:40:39	1.72
+++ wikisrc/ports/evbarm/raspberry_pi.mdwn	2018/10/30 23:09:40	1.78
@@ -14,40 +14,40 @@ Initial, limited, Raspberry Pi support w
 
 ## NetBSD 7 and NetBSD 8
 
- - RaspberryPi 1, and 2 (including SMP)
- - Raspberry Pi 3 (excluding WiFi and bluetooth)
- - multi-user boot with root on SD card
+ - RaspberryPi 1, 2, 3 (except Pi 3 builtin WiFi and bluetooth)
+ - multiple processors on 2/3
+ - boots normally to multiuser, with FAT32 boot partition on uSD
+ - root filesystem can be uSD or USB-attached mass storage
  - serial or graphics console (with EDID query / parsing)
+ - X11 via HDMI
+ - GPU (VCHIQ) - 3D and video decode. man page missing.
+ - USB host controller - dwctwo(4) and most devices work
+ - USB Ethernet - usmsc(4)
  - DMA controller driver and sdhc(4) support
+ - RNG
  - Audio: works. man page missing.
- - I²C: works, could use enhancements, man page
  - GPIO
- - RNG
+ - I²C: works, could use enhancements, man page
  - SPI: could use enhancements, man page
- - GPU (VCHIQ) - 3D and video decode. man page missing.
- - USB (host) - dwctwo(4)
- - USB Ethernet - usmsc(4)
- - X windows.
 
 ## NetBSD current
 
- - Raspberry Pi 3 bluetooth
+ - Raspberry Pi 3 builtin bluetooth
  - Raspberry Pi 3 new SD host controller driver
 
 ## What needs work
 
  - USB (host); isochronous transfers.
- - WiFi
+ - Raspberry Pi 3 builtin WiFi
 
 # CPU types
 
-Note that one can also use code for earlier models on later models.
-
  - Raspberry Pi 1 uses "earmv6hf".
  - Raspberry Pi 2 uses "earmv7hf".
  - Raspberry Pi 3 uses "earmv7hf".
 
-See also [[NetBSD/aarch64|aarch64]] for running the Pi 2/3 in 64-bit mode.
+Note that one can run earmv6hf code on the 2 and 3.  See also
+[[NetBSD/aarch64|aarch64]] for running the Pi 2/3 in 64-bit mode.
 
 # Installation
 
@@ -132,6 +132,13 @@ every few weeks.
 
  - [https://github.com/ebijun/NetBSD/blob/master/RPI/RPIimage/Image/README](https://github.com/ebijun/NetBSD/blob/master/RPI/RPIimage/Image/README)
 
+# Maintaining a system
+
+## vcgencmd
+
+The program vcgencmd can be found in pkgsrc/misc/raspberrypi-userland.
+
+
 ## Updating the kernel
 
  - Build a new kernel, e.g. using build.sh. It will tell you where the ELF version of the kernel is, e.g.
@@ -145,9 +152,30 @@ every few weeks.
  - Depending on your hardware version, copy this either to /boot/kernel.img (First generation Pi, Pi Zero hardware) or to /boot/kernel7.img (Pi 2, Pi 3 hardware)
  - reboot
 
+## Updating the firmware
+
+A section below describes the process of updating NetBSD's copy of the firmware from upstream, with testing, by NetBSD developers.  This section is about updating a system's firmware from the firmware in a version of NetBSD.
+
+TODO: Explain where the firmware is in the source tree, and if it is in the installed system image (such as /usr/mdec).  Explain any particular cautions.
+
+## Booting
+
+The device boots by finding a file "bootcode.bin".   The primary location is a FAT32 partition on the uSD card, and an additional location is on a USB drive.  See the [[upstream documentation on booting]](https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/) and read all the subpages.
+
+The standard approach is to use a uSD card, with a fdisk partition table containing a FAT32 partition marked active, and a NetBSD partition.  The NetBSD partition will then contain a disklabel, pointing to an FFS partition (a), a swap paritiion (b) and the FAT32 boot partition mounted as /boot (e).  The file /boot/cmdline.txt has a line to set the root partition.
+
+One wrinkle in the standard approach is that the disk layout is "boot swap /", but the NetBSD fdisk partition starts at the location of /.   The / partition can hold a disklabel, while swap cannot.   It is normal to have swap after / (and thus within the fdisk partition), but the arrangement used permits growing / on first boot, for the typical case where a larger uSD is used, compared to the minimum image size.
+
+An alternate approach is to have the boot FAT32 partition as above, but to have the entire system including root on an external disk.  This is configured by changing root=ld0a to root=sd0a or root=dk0 (depending on disklabel/GPT).  Besides greater space, part of the point is to avoid writing to the uSD card.
+
+A third approach, workable on the Pi 3 only, is to configure USB host booting (already enableed on the 3+; see the upstream documentation) and have the boot partition also on the external device.  In this case the external device must have an MBR because the hardware's first-stage boot does not have GPT support.   \todo Explain if this has been observed to work.
+\todo In theory the [[procedure to program USB host boot mode]](https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/msd.md) will function on a NetBSD system because the programming is done by bootcode.bin.
+
+\todo Explain USB enumeration and how to ensure that the correct boot and root devices are found if one has e.g. a small SSD for the system and a big disk.
+
 # Wireless Networking
 
-  Note that the built-in WiFi in the RPI3 is not yet supported.
+Note that the built-in WiFi in the RPI3 is not yet supported.   USB WiFi interfaces (that work on NetBSD in general) should all work.
 
  - A Realtek 802.11n USB adaptor configures as urtwn(4).
    - Configure with wpa_supplicant in /etc/rc.conf -