Plan 9 Installation for	Raspberry Pi Zero WH

WARNING: Make sure to purchase	a  raspberry  pi  with	GPIO
headers	 pre-soldered.	 For  the Pi Zero W, it	is marked as
the Pi Zero WH.	If your	board does  not	 have  headers,	 you
will  need  to	buy  headers and solder	them on, or else you
will be	unable to connect  to  the  UART  for  serial  debug
console.

First, download	Richard	Miller's Plan 9	image:

https://9p.io/sources/contrib/miller/9pi.img.gz

gunzip the file	to get 9pi.img,	then use  dd  to  copy	this
image onto a microSD card.

Next, we need to configure  config.txt	and  cmdline.txt  to
specify	  the  proper  boot  settings.	For  reference,	 see
https://www.raspberrypi.com/documentation/computers/config_txt.html.

Mount the microSD card and make	a few edits.

In cmdline.txt,	add this definition

readparts=1    nobootprompt=local    console='0	    b115200'
ether1=type=4330 nvram='#S/sdM0/nvram'

to the end of the line.	This will accomplish several things:
it will	configure the serial console, enable the wifi device
in the kernel, and specify the location	of nvram.

NOTE: everything must be on a single command line.  Multiple
lines will not be parsed correctly in cmdline.txt.

If you do not have a display, you may  want  to	 remove	 the
default	 boot  user of glenda so you get a normal rc prompt.
To do so, remove user=glenda from cmdline.txt.

In config.txt, put these lines in the [pi0] block:

enable_uart=1 core_freq=250

You  will  need	  a   USB   to	 TTL   serial	cable	(see
https://www.adafruit.com/product/954).	 It must be attached
to	    the		 correct	  pins		(see
https://learn.adafruit.com/raspberry-pi-zero-creation/give-
it-life)

Afterwards, if	the  machine  to  which	 the  USB  cable  is
connected is running Linux, you	might run a command such as:

$ sudo screen /dev/ttyUSB0 115200

Afterwards, you	should see output like the following:









			   - 2 -


Plan 9 from Bell Labs  board  rev:  0x9000c1  firmware	rev:
1648128071  vcore  reports memory = 0x1f000000 cpu0: 1000MHz
ARM 1176JZF-S clocks: CPU  1000000000  core  250000000	UART
48000000 EMMC 200000000	fp: 16 registers,  simd	fp: arm	arch
VFPv2; rev 5 #l0: usb: 100Mbps port 0x0	irq -1:	000000000000
#u/usb/ep1.0: dwcotg: port 0X0 irq 9 496M memory: 52M kernel
data, 444M user, 1926M swap user[none]:	pi

At this	point, it's recommended	to continue configuration as
pi, since pi is	hostowner:

time...	 fossil(#S/sdM0/fossil)...version...  init: starting
/bin/rc	  Can't	  cd   /usr/pi:	 '/usr/pi'  does  not  exist
lib/profile: rc: .: can't open:	 '/bin/lib'  file  does	 not
exist init: rc exit status: rc 31: error

init: starting /bin/rc %