[Arm-netbook] building a device driver

[lkcl luke]

On Mon, Jun 18, 2012 at 7:26 PM,  <simon at koala.ie> wrote:
> On Mon, 18 Jun 2012 18:14:19 +0100, lkcl luke <luke.leighton at gmail.com>
> wrote:
>
>> On Mon, Jun 18, 2012 at 5:14 PM,  <simon at koala.ie> wrote:
>>  hmm, what's the hardware - is it a USB device, for example?  if so,
>> can you do "lsusb" and report its id (plug it into an x86 pc running
>> gnu/linux if that's easier).  also do you know: does the device driver
>> already exist in the linux kernel source code?
>
> the device is a digital persona U.are.U 4500 fingerprint reader
> it is a USB device [05ba:000a].
>
> digital person provide a driver for linux in source code.
> i have compiled it for my kernel on my desktop machine, installed it and
> run the demo apps.
> my questions revolve around doing this for a tablet where i may or may not
> have access to the kernel source.
> how do i compile against an existing kernel?

 yeaahhh, you shouldn't have bought a device that didn't have the full
kernel source code, should you? slapped wrist :)

 as henrik says, you can find a "close match" - cat /proc/version and
if they've actually bothered to properly keep the source code
up-to-date the revision number there should tell you what you need to
know: you can grab that, cross-compile as a module and off you go.
mileage may vary.

 but seriously, you have to ask yourself the question: are the numbers
(of devices) being purchased _really_ worth the software
[reverse-]engineering time?

 hey - oo look, cute: that device is supported by a library that has a
PAM module for it, so it can be used for login authentication
purposes.  cool!
http://ubuntuportal.com/2011/11/fingerprint-gui-1-02-recorder-and-scanner-fingerprint.html

 l.