PiFlash: Linux utility to flash SD cards for Raspberry Pi computers

PiFlash
Linux Utility to flash SD cards
for Raspberry Pi computers
Presented by Ian Kluft
Silicon Valley Perl (SVPerl)
Sunnyvale, California
February 7, 2019

What is PiFlash?
●
Linux utility to write SD cards for Raspberry Pi
●
I originally wrote piflash in Dec 2016 for myself
●
Presented to SVPerl in Feb 2017
●
Part of OpenSource.com article in Mar 2017
●
Source code on GitHub
– github.com/ikluft/piflash
●
Installable as Perl module from CPAN
– metacpan.org/pod/PiFlash
●
This is an update on PiFlash

The main ideas behind PiFlash
●
For new users
– Safety: it will make
sure it’s only writing to
an SD card
– Prevents accidental
erasure of disks you
wanted to keep
●
For experts
– Automatically detects
input file format to
unpack/decompress
image from zip, tar, gz,
xz files
– More automation coming
with plugin support

What does PiFlash mean?
●
SD (“secure digital” standard) cards
are non-volatile meaning they don’t
lose their content when powered down
●
The chip technology is called “flash
memory”
●
Writing to a flash memory is shortened
to “flashing” it
●
PiFlash writes a bootable OS (usually
Linux) for a Raspberry Pi to an SD card

What is a Raspberry Pi?
●
Credit card sized single board
computer
●
Intended for education
– Inexpensive so kids can learn
programming more easily
●
Popular among do-it-yourself
project builders, or “Makers”
●
ARM processor, 64-bit ARMv8
in current Raspberry Pi 3

History of the Raspberry Pi
●
Started by UK CompSci
professor Eben Upton
●
College freshman didn’t have
experience playing with
computers
●
Needed an inexpensive
computer for kids to learn
●
Raspberry Pi released 2012
●
Low cost: US$25 without
Ethernet, $35 with net
●
Original expected demand was
10,000 units total
●
10 millionth shipped in 2016
●
Developed by non-profit
Raspberry Pi Foundation
●
Licensed to manufacturers

Popularity soars with Maker Community
●
A “Maker” is generally anyone who
builds things
●
Anyone can be a Maker – you too
●
Raspberry Pi instantly became
wildly popular with Makers as a
cheap embedded computer
●
Best when you need the power of
Linux
– It may be overkill when simpler
electronics will work
●
Hardware video acceleration made
it good for displaying video on HDMI
●
GPIO (general purpose I/O) pins
can be optionally used for
electronics interfacing
●
Networking makes RasPi devices
able to remote sense or control
●
For analog/digital electronic
projects, Arduino is popular
competing project board

Based on ARM processor
●
This is different if you’re used to
Intel x86 computers
●
ARM is a “microcontroller” aimed at
low-power devices
●
Most phones & embedded
computers use ARM today
●
Raspberry Pi originally used 32-bit
ARM6
– limited OS support mostly Debian
Linux, OpenElec
●
RasPi 2 & 3 are 64-bit ARM8
– wider OS support: more Linux
distros, FreeBSD, Win10 IoT
●
binaries must be compiled for
ARM – can’t use x86 binaries
– Debian Linux → Raspbian
– Ubuntu & Fedora: ARM spins
– FreeBSD → RaspBSD
– Windows 10 → Win10 IoT

Raspberry Pi Models
Model: RasPi 1 RasPi 1+ RasPi 2 RasPi Zero RasPi 3 RasPi
ZeroW
Raspi 3+
Introduced 2012 2014 2015 2015 2016 2017 2018
Availability discontinued current model
Processor ARM6 32bit ARM6 32bit ARM8* 64bit ARM6 32bit ARM8 64bit ARM6 32bit ARM8 64bit
CPU speed 700MHz 700MHz 900MHz 1GHz 1.2GHz 1GHz 1.4GHz
memory 256MB 512MB 1GB 512MB 1GB 1GB 1GB
USB2 ports 1 on A
2 on B
4 4 1 4 1 4
Flash boot SD MicroSDHC
* RasPi 2 before v1.2 was 64bit ARM7 CPU, upgraded to ARM8 same as RasPi 3

Downloadable System Boot Images
●
NOOBS
– “New Out of the Box System” by
Raspberry Pi Foundation
– For beginners, contains multiple OS
images that it can install for you
– Bigger image because it includes lots of
OS’s
●
Raspbian
– Debian Linux for Raspberry Pi
– Official RasPi reference system
– Works on all RasPi models
●
Ubuntu & Fedora
– Both support RasPi 2 & 3 on ARM versions
●
RaspBSD
– FreeBSD configured for RasPi 2 & 3
●
Kodi, OSMC & LibreElec
– Entertainment system distros based on Linux kernel
– Work on all RasPi models
– Beware untrusted plugins: recent malware problems
●
Microsoft Windows 10 IoT Core
– RasPi 3 only
– Not free - requires software license

Types of Projects
●
Desktop
– Conventional computer
●
RasPi 3 powerful enough for low-end
desktop replacement
– USB keyboard & mouse
●
Or TV remote for entertainment
– HDMI monitor
●
Composite video available, not common
– Network – Ethernet or WiFi
●
WiFi built in on RasPi 3
●
USB WiFi common on others
●
Headless
– No keyboard, mouse or monitor
– Software developed on desktop
– Network common but optional
– “Internet of Things” (IoT) device
– Applications:
●
Sensing/measurement/control
●
Robots
●
Drone autopilot (requires FAA registration)
●
Docker container platform
●
Security camera with facial recognition
●
Etc

How to set up a Raspberry Pi
●
Download OS from raspberrypi.org/downloads/
●
Flash SD card with boot system image
– More on that coming up
●
Connect cables, monitor & network
●
Apply power via microUSB power input
– 1A for RasPi 1, 2A for RasPi 2, 2.4A for RasPi 3
– Maybe more for your specific project needs
– Mysterious malfunctions may result from insufficient
power
●
Boot and configure whatever system it is
Docs from raspberrypi.org

Flashing an SD card for Raspberry Pi
●
Raspberry Pi needs SD card to boot
– RasPi 1 uses bigger SD card
– All others use smaller MicroSD
– RasPi 3 also has USB & network boot procedures
●
not for beginners
●
8GB SD card minimum recommended
– Cheapest SD cards are currently 16-32GB
●
Get the right boot image for your system
– If you have a RasPi 1/1+/Zero/ZeroW, there’s usually a
separate image for ARM6
●
RaspberryPi.org has SD flash tools for Windows &
Mac
– Instructions for Windows
– Instructions for MacOS
●
Linux instructions provide no tools
– Biggest point is to identify the correct
device
– You don’t want to accidentally erase
another disk on your system
– You can use PiFlash for Linux
●
In all cases…
– Flashing gigabytes of data will require at
least some minutes of wait, maybe many
– Be patient once you start
– Let it finish

Installing PiFlash
●
From CPAN
– Follow instructions for local Perl modules if needed
– “cpan PiFlash”
●
Also on GitHub
– Download or git-clone from github.com/ikluft/piflash
– “dzil install”
●
Requires Dist::Zilla to build from Git source

PiFlash usage
●
PiFlash is a command-line utility
usage: piflash [--verbose] [--resize] input-file output-device
piflash [--verbose] --SDsearch
piflash --version

PiFlash usage: --version
●
Prints the current version
$ piflash --version
0.1.0

PiFlash usage: --SDsearch
●
Search available block devices for SD cards
●
Any devices listed are the only ones PiFlash will
write to
– Avoids destroying a disk you wanted to keep!
●
Example shows USB and PCI based drivers:
$ piflash --sdsearch
SD cards found: /dev/sdb /dev/mmcblk0

PiFlash usage: writing to an SD
●
Simplest form is input file and output device
$ piflash --resize 2018-11-13-raspbian-stretch-lite.zip /dev/sdb
requested to flash 2018-11-13-raspbian-stretch-lite.zip to /dev/sdb
output device /dev/sdb will be erased
[sudo] password for user:
verify sudo access
flashing 2018-11-13-raspbian-stretch-lite.zip / 2018-11-13-raspbian-stretch-lite.img ->
/dev/sdb
…
done - it is safe to remove the SD card

PiFlash usage: --resize
●
Add –resize to command line to resize the root
filesystem to fill the entire SD card
●
Only works with boot images that have a Linux ext2/3/4
root filesystem
– Not always necessary – some OS’s will do this on first boot
– Works for Raspbian, Ubuntu, Fedora
– Doesn’t work on NOOBS, RaspBSD, Kodi, RISCOS, Windows

Internals of PiFlash
●
You don’t need to know this to use
PiFlash
– But we at SVPerl want to hear about Perl
●
Lowest-level “State” class stores all
parameters from
– Command line
– Operating system configuration
– Input file
– Output device
– It’s all the info needed for support requests
– --verbose parameter dumps the State
●
Contains a fork/exec wrapper to capture status
or output of commands it launches
– Eliminating qx() made perlcritic happy at the -4 level
●
Maintains list of command locations rather than
use $PATH – just being careful since it needs
root privs
●
“lsblk” command inspects output device so we
can tell if it’s an SD card
– Differences tested on PCI and USB SD readers
– That’s expected to cover most cases
– If a device isn’t detected, I’d like to see the verbose
output so I can add it
●
Main() is exception-catching wrapper

Modules in PiFlash package
●
PiFlash.pm – main(),
package version
●
Command.pm –
command launching
wrapper and logging
●
Hook.pm – callback
hooks
●
Inspector.pm – collects
data on system, input file
and output device
●
MediaWriter.pm – flashes
the SD card from input
file
●
State.pm – middleware
data storage layer

Features in development
●
These are chances for you to get involved if
anything sounds interesting
●
Plugin modules via Module::Pluggable
– Any module named under PiFlash::Plugin hierarchy
can be enabled from command line with –plugin
– i.e. PiFlash::Plugin::ModuleName

Features in development: Hooks
●
Callback hooks via PiFlash::Hook
●
Code including plugins can register callbacks
– At start
– After installation
– With mounted boot/root filesystem for system
customization

Possible customizations via plugins
●
These can be done before 1st boot by mounting boot and root filesystems and
running callback hooks to modify them
●
System configuration
– Kernel driver command line settings
– CPU overclocking
– Camera
– Audio/Video
– Network: wired and/or wireless
●
Security
– Change user name/password
– Set SSH key and authorized remote keys

Caveats for customization
●
Raspberry Pi runs ARM binaries
– 32 bit ARMv6 for Pi 1, 1B, Zero & Zero W
– 64 bit ARMv8 for Pi 2, 3 & 3+
●
Installation of software packages are probably not
the same as the system running PiFlash
– X86 binaries won’t work on RasPi
– Similar to all embedded systems development

PiFlash: Linux utility to flash SD cards for Raspberry Pi computers

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PiFlash: Linux utility to flash SD cards for Raspberry Pi computers