= GPSD Installation Instructions
:title: GPSD Installation Instructions
:description: Steps for installing GPSD and verifying its performance.
:keywords: GPSD, GPS, installation
:author: Eric S. Raymond <esr@thyrsus.com>
:robots:index,follow

Here are the steps for installing GPSD and verifying its performance.
They assume you have GPSD available as an installable binary package,

Instructions for building GPSD from source (including cross-building)
are in the file "build.adoc" in the source distribution.

Most of these installation instructions are generic to Linux.  There are
some special notes on installation on *BSD, WSL, OS X, macOS, and the
Raspberry Pi near the end of this file.

== Check that your GPS is live and you can get data from it

Start by making sure you can get data from your GPS, otherwise the later
steps will be very frustrating.  In this command:

      stty -F /dev/ttyXXX ispeed 4800 && cat </dev/ttyXXX

replace ttyXXX with the filename of the port.  This will probably be
either /dev/ttyUSB0 or /dev/ttyS0. If you are on a *BSD Unix or MacOS X,
replace -F with -f.

When you run this command, you should see text lines beginning with $
come to stdout (possibly after a short initial burst of binary
garbage).  If you don't see this, you may have OS-level problems with
your serial support, but more likely have the wrong device.  Look
again.

If you have trouble with the preceding step, check your cabling
first.  Verify that the device is connected and that its power LED
(if it has one) is lit.

If you seem to have some sort of serial-device problem, check that
your kernel properly supports the device you are using.  For GPSes
using an RS-232 port (which is no longer common) you will need
serial-port support compiled into your kernel.  Various USB-to-serial
adapter chips found in GPSes require specific drivers.

Under a stock Linux kernel these will all be loaded on demand when
the USB system sees the appropriate vendor/product ID combinations.
See build.adoc for instructions relating to custom kernels.

== Check that your system configuration will allow GPSD to work

Ensure that device permissions will enable gpsd to read from and write
to GPS devices even after it drops root privileges.  If you are
running Fedora Core, Ubuntu, or stock Debian you can skip this step,
as the stock configuration has the right properties.

gpsd requires two things: (1) that GPS devices have group read and
write enabled, and (2) all of them have the same group ID as a
prototypical device, typically /dev/ttyS0 under Linux or /dev/tty00
under *BSD. It does not actually matter what the owning group is, as
gpsd will look this up on startup.  Alternatively, (3), you can set a
fallback group with the gpsd-group option in case the prototype is not
found: this should be the group that has write access to serial
devices.  On Debian and derivatives including Ubuntu this is "dialout";
on Gentoo/Fedora/openSuse it is "uucp".

Before dropping privileges, gpsd will ensure that it has access to
devices given to it on the command line by forcing their group read
and write permissions on.

On a Linux with udev, check the files in /etc/udev/permissions.d to
ensure that /dev/tty* devices are all created with the same group
and with 0660 permissions.

When gpsd drops privileges, its default is to set uid to 'nobody' and
group to the owning group of the prototype device (the configure
option gpsd-user=foo will cause gpsd to change to 'foo'
instead).

If your system has the Linux hotplug facility installed you can skip
the permission-setting part; the hotplug scripts will force the
permissions for you.  You still have to make sure all the tty devices
are in the same group.

== Check your installation prerequisites

A minimum build of GPSD can run pretty close to the metal; all it
absolutely needs is the C runtime support. The test clients and
various additional features have additional prerequisites:

|===============================================================================
|asciidoctor                  | to build the documentation and www
|dbus                         | gpsd will issue DBUS notifications
|gnuplot                      | to plot gpsprof output.
|GTK                          | for python-GI
|libtinfo5                    | low-level terminfo library (see below)
|libusb-1.0.x or later        | for older Garmin USB devices
|ncurses                      | for cgps and gpsmon clients
|pps-tools                    | for PPS time keeping
|PyGObject                    | for xps and xgpsspeed clients (see below)
|pyserial                     | for ubxtool and zerk in direct-serial mode
|python2.x(x>=6) or 3.y(y>=2) | required for various clients and utilities
|python-cairo                 | for python-GI
|Qt                           | libQgpsmm depends on this
|===============================================================================

Some ncurses packages contain the terminfo library; some break it out
separately as libtinfo5 or libtinfo.

The PyGObject package goes by several names, and is split up into sub
packages different ways, depending on the distribution.  Sometimes
python-gi, python-gobject, python-cairo, etc.  The packages also need
the underlying system libraries (GTK, GLib, etc.)

The asynchronous python module (gps/aiogps.py) and its example client
(example_aiogps.py) require Python 3.6+.

See below for more specific module requirements in the individual
distribution instructions.

== Installing gpsd

=== Install your distributions package(s)

Up-to-date gpsd packages are generally available for Linux distributions
including Debian and derivatives (including Ubuntu and Mint), Fedora and
derivatives (including CentOS), openSUSE, PCLinuxOS, Mageia, Gentoo, and
Slackware.  In the embedded space, CeroWRT and Yocto carry GPSD. The
GPSD package in the FreeBSD ports tree is also reliably up to date.
Even if your distribution is not on this list, it is quite likely GPSD
has already been packaged for it.

Whatever distribution you are running, the name of the core GPSD
package containing the service daemon is almost certainly "gpsd".
However, many distributions break up GPSD into separate installable
packages for the core daemon and clients; you should search your
repository index for anything with gpsd as a prefix.

=== Install from source code

Directions for installing from source are in the file build.adoc found
in the source distribution.

== How to test the software

1. Start gpsd.  You'll need to give it as an argument a path to
a serial or USB port with a GPS attached to it.  Your test command
should look something like this:

       gpsd -D 5 -N -n /dev/ttyUSB0

2. Once gpsd is running, telnet to port 2947. You should see a
greeting line that's a JSON object describing GPSD's version.
Now plug in your GPS (or AIS receiver, or RTCM2 receiver).

3. Type '?WATCH={"enable":true,"json":true};' to start raw and
watcher modes.  You should see lines beginning with '{' that are
JSON objects representing reports from your GPS; these are reports
in GPSD protocol.

4. Start the xgps or cgps client.  Calling it with no arguments
should do the right thing.  You should see a display panel with
position/velocity-time information, and a satellite display.  The
displays won't look very interesting until the GPS acquires satellite
lock.

5. Have patience.  If you are cold-starting a new GPS, it may take
15-20 minutes after it gets a skyview for it to download an ephemeris
and begin delivering fixes.

6. A FAQ and troubleshooting instructions can be found at the GPSD
project site.

== Once you have verified correct operation

1. If you installed from a '.deb' package under Debian or a
Debian-derived system, you may need to `dpkg-reconfigure -plow gpsd' to
enable the hotplug magic ("Start gpsd automatically").

2. Check out the list of supported hardware at the Hardware page on
the GPSD project's website. If your GPS isn't on the list, please send
us information to add a new line to the table.  Directions are
included on that page. We can also use updates of the latest version
number known to work with hardware already supported.

3. GPSD includes gpsd.php, a PHP script, that you can use to generate
a PHP status page for your GPS if you wish. (It may not be in the
core package.)  It should be manually copied to your HTTP document
directory.  The first time it's invoked, it will generate a file
called 'gpsd_config.inc' in that directory containing configuration
information; edit to taste.

4. There are other non-essential scripts that may be useful; these
are in the contrib/ directory of the source.  They may not be available
in the packages available from distributions.

For special instructions related to using GPSD for time service, see the
GPSD Time Service HOWTO in the distribution or on the web.

== Apple Desktop

=== Special Notes for macOS X Installation

gpsd will build, install and run on macOs. Install the Xcode application
from the Apple store. Then install Homebrew (https://brew.sh/) to get
all the stuff you need, like git, scons, python, etc.

As a normal user, install homebrew, then install scons and asciidoctor.
Installing scons pulls in python3. Brew will become root as needed, so
starting asd a normal user is just security theater.

--------------------------------------------------------------
$ /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
$ brew install scons asciidoctor
--------------------------------------------------------------

Now you need to become root. Make a place for the gpsd source to live,
use git to install it there, then go there.  Build gpsd with "scons",
then install it with "scons install"

--------------------------------------------------------------
# mkdir -p /usr/local/src/GPS
# cd /usr/local/src/GPS
# git clone https://gitlab.com/gpsd/gpsd.git
# cd gpsd
# scons && scons install
--------------------------------------------------------------

=== Special Notes for OS X Installation

gpsd will build, install and run on OS X (osX).  The easiest way to
do so is to first install the MacPorts package.  Follow their install
procedure at: http://www.macports.org/install.php

Then use their port command to install scons.  Optionally git if you
want to access the development source.  Optionally install libxslt and
xmlto to build the documentation.

--------------------------------------------------------------
# port install scons
# port install git
# port install libxslt
# port install xmlto
--------------------------------------------------------------

Currently the osX port does not work with Qt5.  To see the build
failure:

--------------------------------------------------------------
# port install qt5
# scons --config=force qt_versioned=5
--------------------------------------------------------------

If you have Qt5 installed, and want to avoid the build failure, bui.d
this way:

--------------------------------------------------------------
# scons --config=force qt=no
--------------------------------------------------------------

While running gpsd, or scons check, you may run out of shared memory
segments.  If so, you will see this error message:

--------------------------------------------------------------
gpsd:ERROR: shmat failed: Too many open files
--------------------------------------------------------------

By default OS X allows a very small number of shared segments.  You
can check your allowed maximum number of shared segments, then increase
the maximum number, with these commands:

--------------------------------------------------------------
# sysctl kern.sysv.shmseg=8
kern.sysv.shmseg: 32 -> 8
#   sysctl -a  | fgrep shmseg
kern.sysv.shmseg: 8
# sysctl kern.sysv.shmseg=16
kern.sysv.shmseg: 8 -> 16
#   sysctl -a  | fgrep shmseg
kern.sysv.shmseg: 16
--------------------------------------------------------------

If you are using a USB based GPS you will likely need the Prolific
PL2303 driver.  You can find it here:
http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=229&pcid=41

== Special Notes for Raspberry Pi Installation

gpsd will build, install and run on the Raspberry Pi (RasPi) and Pi 2
using Debian jessie.  Other distributions based on
Debian (raspbian, etc) will work fine as well.  The gpsd
package in Debian Wheezy is known to be flaky, be sure to update to a
new version of gpsd from source.

=== Raspbian

Before compiling gpsd from source, you will need to update your system
as root.  Switching to the latest Raspbian distribution (Buster) is
strongly recommended.

--------------------------------------------------------------
# apt-get update
# apt-get dist-upgrade
# rpi-update
# reboot
--------------------------------------------------------------

Multiple versions of gpsd can not co-exist on the same system.  You need
to ensure gpsd from a package is not on the system:

--------------------------------------------------------------
# apt purge gpsd
--------------------------------------------------------------

Then install the required packages:

--------------------------------------------------------------
# apt-get install scons libncurses5-dev python-dev pps-tools
# apt-get install git-core
--------------------------------------------------------------

Git-core is required to build from a git repository.  pps-tools is for
PPS timing.

The rest of the installation is just as for any other source based
install, as noted in the file *build.adoc*.

=== Other Debian derivatives (including stock)

==== Buster (10) with python2

These Buster instructions seem to also work for Devuan and Maemo Leste.

Multiple versions of gpsd can not co-exist on the same system.  You need
to ensure gpsd from a package is not on the system:

--------------------------------------------------------------
# apt purge gpsd
--------------------------------------------------------------

Then update your system, and install the packages required by gpsd:

--------------------------------------------------------------
# apt-get update
# apt-get dist-upgrade
# reboot
# apt-get install scons libncurses-dev python-dev pps-tools
# apt-get install git-core
# apt-get install build-essential manpages-dev pkg-config
--------------------------------------------------------------

If "apt-get install scons" fails, check the file "/etc/apt/sources.list".

Git-core is required to build from a git repository.
pps-tools is for PPS timing.
Build-essential installs the compiler and associated tools.
Manpages-dev is the associated man pages.
Pkg-config is a helper for scons.

Gtk3 is only required to run xgps and xgpsspeed.  You do not need a local
X11 server installed, but it still pulls in a lot of packages.

--------------------------------------------------------------
# apt-get install python-gi-dev python-cairo-dev
# apt-get install python-gobject-2-dev libgtk-3-dev
--------------------------------------------------------------

Ubxtool and zerk may optionally use the pyserial module for
direct connection to the GNSS receiver:

--------------------------------------------------------------
# apt-get install python-serial
--------------------------------------------------------------

gpsd may optional connect to dbus with the libdbus package:

--------------------------------------------------------------
# apt-get install libdbus-1-dev
--------------------------------------------------------------

Some very old Garmin USB devices need libusb:

--------------------------------------------------------------
# apt-get install libusb-1.0-0-dev
--------------------------------------------------------------

If you wish to build the documentation, be warned it pulls in a
lot of packages.  Build the documentation is a prerequisite to
building the HTML files for the website (www/), and also to make
a source tarball (scons dist).  To install the tools to build the
documentation:

--------------------------------------------------------------
apt-get install xsltproc docbook-xsl xmlto asciidoctor
--------------------------------------------------------------

The rest of the installation is just as for any other source based
install, as noted in the file *build.adoc*.

--------------------------------------------------------------
# git clone https://gitlab.com/gpsd/gpsd.git
# cd gpsd
# scons --config=force && scons install
--------------------------------------------------------------

==== Jessie (8)

Multiple versions of gpsd can not co-exist on the same system.  You need
to ensure gpsd from a package is not on the system:

--------------------------------------------------------------
# apt purge gpsd
--------------------------------------------------------------

Then install the required packages:

--------------------------------------------------------------
# apt-get install scons libncurses5-dev python-dev pps-tools
# apt-get install git-core
--------------------------------------------------------------

Git-core is required to build from a git repository.  pps-tools is for
PPS timing.

The rest of the installation is just as for any other source based
install, as noted in the file *build.adoc*.


==== Wheezy

Multiple versions of gpsd can not co-exist on the same system.  You need
to ensure gpsd from a package is not on the system:

--------------------------------------------------------------
# apt purge gpsd
--------------------------------------------------------------

Wheezy, being older, requires updating the tools for compiling
and testing gpsd:

You need scons at 2.3.0 or higher to build.
If your scons is less than 2.3.0 you will need to get a newer scons
from wheezy-backport.  Partial instructions are detailed here:
https://backports.debian.org/Instructions/

Basically you need to add this line to /etc/apt/sources.list:

--------------------------------------------------------------
deb http://http.debian.net/debian wheezy-backports main
--------------------------------------------------------------

Then do another update:

--------------------------------------------------------------
apt-get update
--------------------------------------------------------------

Which may lead you to this error if you lack a full set of debian keys:

--------------------------------------------------------------
W: GPG error: http://http.debian.net wheezy-backports Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553
--------------------------------------------------------------

Partial but detailed instructions to fix that are here:

--------------------------------------------------------------
https://wiki.debian.org/SecureApt
--------------------------------------------------------------

Use either of the following code blocks.  The first is more robust:

--------------------------------------------------------------
apt-get install debian-archive-keyring
--------------------------------------------------------------

--------------------------------------------------------------
gpg --keyserver pgpkeys.mit.edu --recv 8B48AD6246925553
gpg -a --export 46925553 |  apt-key add -
apt-get update
--------------------------------------------------------------

You can now install scons from the wheezy-backports repository:

--------------------------------------------------------------
apt-get -t wheezy-backports install scons
--------------------------------------------------------------

and other tools:

--------------------------------------------------------------
# apt-get install scons libncurses5-dev python-dev pps-tools
# apt-get install git-core
--------------------------------------------------------------

Git-core is required to build from a git repository.  pps-tools is for
PPS timing.

The rest of the installation is just as for any other source based
install, as noted in the file *build.adoc*.

==== Ubuntu Buster 20

If you have Raspbian Buster, that is not this.

Preliminary install notes.

Multiple versions of gpsd can not co-exist on the same system.  You need
to ensure gpsd from a package is not on the system:

--------------------------------------------------------------
# apt purge gpsd
--------------------------------------------------------------

Then install the required packages:

--------------------------------------------------------------
apt install gcc scons python-gi python-gi-cairo g++
apt install python-gobject libgtk-3-dev
apt install libncurses5-dev libtinfo-dev  pps-tools
apt install gir1.2-gtk-3.0
--------------------------------------------------------------

If you wish to build the documentation, be warned it pulls in a
lot of packages.  Build the documentation is a prerequisite to
building the HTML files for the website (www/), and also to make
a source tarball (scons dist).  To install the tools to build the
documentation:

--------------------------------------------------------------
apt install xsltproc docbook-xsl xmlto asciidoctor
--------------------------------------------------------------

The rest of the installation is just as for any other source based
install, as noted in the file *build.adoc* .

==== Ubuntu 18.04 LTS

Preliminary install notes.

If you have Raspbian Buster, that is not this.

Multiple versions of gpsd can not co-exist on the same system.  You need
to ensure gpsd from a package is not on the system:

--------------------------------------------------------------
# apt purge gpsd
--------------------------------------------------------------

Then install the required packages:

--------------------------------------------------------------
apt install gcc scons python-gi python-gi-cairo g++
apt install libncurses5-dev libtinfo-dev  pps-tools
apt install gir1.2-gtk-3.0
--------------------------------------------------------------

If you wish to build the documentation, be warned it pulls in a
lot of packages.  Build the documentation is a prerequisite to
building the HTML files for the website (www/), and also to make
a source tarball (scons dist).  To install the tools to build the
documentation:

--------------------------------------------------------------
apt install xsltproc docbook-xsl xmlto asciidoctor
--------------------------------------------------------------

The rest of the installation is just as for any other source based
install, as noted in the file *build.adoc*.

=== Other Raspberry Pi tips

Any USB connected GPS that is known to work with gpsd will work fine on
the RasPi.  No special instructions apply.

A very popular option is to install the AdaFruit Ultimate GPS HAT.  With
this GPS you also get a good 1PPS signal.  This works as any other GPS
with gpsd, but there are two things to note.  The GPS takes over the
serial console: /dev/ttyAMA0.  The PPS signal will be on GPIO Pin #4.

Only three specific changes need to be made to make the HAT work.  First
in the file /boot/cmdline.txt, remove this part "console=ttyAMA0,115200
kgdboc=ttyAMA0,115200".  That frees the serial port from console use so
the GPS can use it.

Second you need to tell the boot process to load the pps_gpio module
and attach /dev/pps0 to GPIO pin 4.  Do that by adding this line
to the bottom of /boot/config.txt: dtoverlay=pps-gpio,gpiopin=4

Reboot so those changes take effect.

Run gpsd like this:

--------------------------------------------------------------
~ # gpsd -D 5 -N -n /dev/ttyAMA0 /dev/pps0
--------------------------------------------------------------

If you are on the RasPi with gpsd version 3.17, or above, /dev/pps0 can
be autodetected, and used for PPS if available.

gpsd 3.17 and up only:

--------------------------------------------------------------
~ # gpsd -D 5 -N -n /dev/ttyAMA0
--------------------------------------------------------------

You can verify gpsd is using the PPS by running ntpshmmon:

--------------------------------------------------------------
~ # ntpshmmon
#      Name   Seen@                Clock                Real               L Prec
sample NTP0 1461619703.641899335 1461619703.445224418 1461619703.000000000 0  -1
sample NTP2 1461619703.642203397 1461619702.999262204 1461619703.000000000 0 -20
sample NTP0 1461619704.142097363 1461619703.445224418 1461619703.000000000 0  -1
sample NTP2 1461619704.142204134 1461619703.999258157 1461619704.000000000 0 -20
--------------------------------------------------------------

If you do not see NTP2 then you misconfigured the pps_gpio driver.

The serial time is provided to ntpd on NTP0, the PPS time is on NTP2, not
on NTP1 like described earlier.  So your ntp.conf will need to be adjusted
from:

--------------------------------------------------------------
# GPS PPS reference (NTP1)
server 127.127.28.1 prefer
fudge 127.127.28.1 refid PPS
--------------------------------------------------------------

To:

--------------------------------------------------------------
# GPS PPS reference (NTP2)
server 127.127.28.2 prefer
fudge 127.127.28.2 refid PPS
--------------------------------------------------------------

Now proceed as for any other operating system to use gpsd.

Be sure to validate that your PPS signal is not offset by the pulse
width.  That would mean gpsd is using the wrong edge.

Detailed instructions are available from their website:
https://learn.adafruit.com/adafruit-ultimate-gps-hat-for-raspberry-pi/

You will need to dig deeper to make the PPS work, here is a good reference:
http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html

== BSD derivatives ==
=== Special Notes for FreeBSD Installation ===

gpsd will build, install and run on FreeBSD.
Due to the missing CAN bus support (linux/can.h), NMEA2000/CAN
is not supported on FreeBSD.

Use their pkg command to install scons, and optionally git if you
want to access the development source.

If you want to build the QT bindings, you'll also need the
qt5-network and pkgconf packages.

--------------------------------------------------------------
# pkg install scons
# pkg install git
# ln -s /usr/local/bin/python2.7 /usr/local/bin/python
# ln -s /usr/local/bin/python2.7 /usr/local/bin/python2
# ln -s /usr/local/bin/python3.6 /usr/local/bin/python3
# git clone https://gitlab.com/gpsd/gpsd.git
# cd gpsd
# scons --config=force && scons install
--------------------------------------------------------------

FreeBSD fails to create the python links as required by PEP394.
So you need to add them yourself, as above.

=== Special Notes for NetBSD 8.1 Installation

gpsd will build, install and run on NetBSD.

Use their 'pkg_add' command to install pkgin.  Then use pkgin to
install the required tools.

--------------------------------------------------------------
# export PKG_PATH=\
"http://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/amd64/8.1/All"
# pkg_add -v pkgin
# echo http://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/amd64/8.1/All > \
   /usr/pkg/etc/pkgin/repositories.conf
# pkgin update
# pkgin install python37 py37-curses
# ln -s /usr/pkg/bin/python3.7 /usr/pkg/bin/python
# ln -s /usr/pkg/bin/python3.7 /usr/pkg/bin/python3
# pkgin install py37-scons
# pkgin install ncurses
# pkgin install openssl mozilla-rootcerts
# mozilla-rootcerts install
# pkgin install git
# git clone https://gitlab.com/gpsd/gpsd.git
# cd gpsd
# scons --config=force && scons install
--------------------------------------------------------------

=== Special Notes for OpenBSD 6.6 Installation

gpsd will build, install and run on NetBSD.

All you need for a basic gpsd install is scons and git.  Then
create the missing python link.

--------------------------------------------------------------
# pkg_add scons
# pkg_add git
# ln -s /usr/local/bin/python2 /usr/local/bin/python
--------------------------------------------------------------

Then install the normal way.

--------------------------------------------------------------
# git clone https://gitlab.com/gpsd/gpsd.git
# cd gpsd
# scons --config=force && scons install
--------------------------------------------------------------

== Special Notes for Fedora derivatives
=== Special Notes for Fedora 32, 33 Installation

gpsd currently will build, install and run on Fedora 32, 33.

Install the gcc compiler and tools.  Clone the gpsd source, and then
build it.

--------------------------------------------------------------
# dnf install -y gcc-c++ python3-devel scons xmlto asciidoctor bzip2
# dnf install -y xz git dnf-plugins-core
# git clone https://gitlab.com/gpsd/gpsd.git
# cd gpsd
# scons
# dnf builddep -y gpsd-*/packaging/rpm/gpsd.spec
# scons
--------------------------------------------------------------

If you wish to make an rpm of your build:

--------------------------------------------------------------
# scons dist
# dnf install -y chrpath fedora-packager rpmdevtools
# rpmdev-setuptree
# cp gpsd-3*.tar.* ~/rpmbuild/SOURCES/
# rpmbuild -ba gpsd-3*/packaging/rpm/gpsd.spec
--------------------------------------------------------------


=== Special Notes for CentOS 7 Installation

gpsd currently will build, install and run on CentOS 7.

Install the gcc compiler and tools.  Install EPEL.

Note: there is no EPEL for i386.

Use the yum command to install git if you
want to access the development source.

--------------------------------------------------------------
# yum group install "Development Tools"
# yum install git
# yum install \
   https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
# yum install scons
# yum install python-devel
# yum install ncurses-devel
# yum install pps-tools-devel
# git clone https://gitlab.com/gpsd/gpsd.git
# cd gpsd
# scons
--------------------------------------------------------------

== Special Notes for Windows

Only Windows Subsystem for Linux 1 provides a reasonable means
of running gpsd at this time. WSL2 lacks a GUI, USB and serial
support making it unsuitable at this time.

=== About WSL 1

WSL 1 is  a component of Microsoft
Windows that implements an alternate kernel. Linux
distributions, notably Alpine, Debian, Kali, OpenSUSE, and
Ubuntu may run on top of it.

There are some issues known which affect gpsd.

* /dev/ttyS* nodes have a 1 indexed number, like in MS Windows.
* Windows 10 may attempt to use your GPS itself.
* Older pl2303 (knockoff) serial chipsets are no longer supported \
  in Windows 10

=== Installing a Linux distribution on WSL 1 or WSL 2

1. Install a Linux distribution by clicking on the `Microsoft Store` \
Icon in the taskbar.
2. Click on the search icon (it is a magnifying glass).
3. Type in 'Linux' or the name of a supported distribution. (see list)
4. Click on the icon of your chosen Linux Distribution
5. Click 'Get' then click 'Install' and busy-wait.
6. Click on the start menu and scroll to your Linux distribution and \
click it.
7. Follow the distribution-specific on-screen instructions to finish \
installing your Linux distribution.

=== Recommended packages

Due to current WSL limitations, it is recommended at this time that you
only install the equivalent of the following packages on your distribution.

----
Python
SCons (preferably 3.0+)
ncurses-dev (to build/run cgps and gpsmon)
asciidoctor (to build the documentation)
xmlto (to build the man pages)
----

Optionally, the following packages might also be installed
----
pyserial (for direct control of UBlox GPS and GREIS devices)
gnuplot (to generate graphs of gpsprof data)
libusb-dev (to possibly use crusty old Garmin GPS receivers)
git (if building from the development sources)
----

=== Building on WSL 1 or WSL 2

1. Get the list of packages from the appropriate section above.
2. Follow instructions in the distro-specific section above.
