To avoid cluttering the manual page, notes are separately presented
here regarding the non-free firmware many wireless network controllers
require in order to function.  Troubles with wireless and its firmware
are introduced, after which two possible solutions to the
troubles follow.

WIRELESS FIRMWARE TROUBLES

Many users whose wireless network controllers require non-free firmware
cannot easily install the Debian operating system using only the
official, free ISO CD installation image the Debian Project supplies.
The difficulty is acute if the target device is a small laptop or other
portable machine that lacks an Ethernet port, for to function, the
device's wireless requires non-free firmware that, frustratingly, could
have been fetched wirelessly for installation if only the wireless were
already functioning.

The mirrorrib(1) program alone half-solves the problem by mirroring the
relevant part of the Debian archive, including the archive's non-free
area (in which the needed firmware resides) and including backports,
into a local repository on the machine's hard drive.  As long as the
local repository resides somewhere other than the hard-disk partition
onto which the operating system is to be installed, one can

    1. use the official, free ISO CD installation image to install or
       reinstall the operating system; and then
    2. install the firmware the wireless requires directly from the
       local repository.

The network is never accessed until both installations are complete.

The method is as elegant as any method involving non-free firmware is
likely to be.  However, the method's weakness is that it relies on the
local repository already to be present before installation of the
operating system begins.  If one could only place the repository on a
hard-drive partition once, one could then reinstall as many times as
one liked, but putting the repository on once is frustrated by the
not-yet-functioning wireless.

SUGGESTED SOLUTION:  TWO USB FLASH DRIVES

The solution this writer recommends to the typical user is to mount a
high-capacity USB flash drive on another Debian machine, one that has a
wired Internet connection.  Have mirrorrib(1) build the
repository *onto the flash drive.*  Then, after the standard
netinst.iso image has been written to another, lower-capacity flash
drive, carry both flash drives over to the other machine -- where the
low-capacity flash drive installs the operating system and the
high-capacity flash drive provides the wireless driver.

Of course, the high-capacity flash drive also provides all other wanted
software, including backports.  The target machine's wireless is never
relied upon, and yet once installation is done, the wireless works.

This solution has the extra advantage that it succeeds even if the
device's hard drive is too small to host the local repository.

ALTERNATE SOLUTION:  UNOFFICIAL ISO CD INSTALLATION IMAGES

Debian's Images Team has been publishing unofficial but
cryptographically signed alternate ISO CD installation images at

    https://cdimage.debian.org/cdimage/unofficial/
      non-free/cd-including-firmware/

As the URL suggests, these images presumably include the
needed firmware.

Installing from the unofficial images is less elegant than the
earlier, two-USB-flash-drive solution for various reasons that will
grow clear to you if you try the unofficial images, but the unofficial
images might be easier for a beginner to try the first time.  No
regular publication praxis for the unofficial images has been
articulated, so mirrorrib(1) is unable automatically fetch the
unofficial images for you, but that's just as well.  If you want the
unofficial images, just download them.

FREE SOFTWARE

Despite the foregoing, special-purpose advice, no solution involving
non-free software is *urged* upon any Debian user.  Debian is about
free software and mirrorrib(1), which is part of Debian, is about free
software, too.

This file's advice is supplementarily for the benefit of specific users
who need or want it.  Other users can disregard.

