looking for decent, current online discussion of user-space drivers

[Robert P. J. Day]

  a colleague asks me about the implications of porting a pile of code
from a non-linux embedded OS to linux, and simply rewriting most of it
as user-space drivers, as opposed to a total rewrite to kernel code.
i'm in no way an authority on user-space drivers, so i'm looking for
any decent, up-to-date discussions, not so much on the technical
aspects, but more the *implications* of doing this.

  i'm aware of mmap(), and i'm reading up on UIO, and i've found a few
online pieces that look informative:

http://www.embedded.com/design/operating-systems/4401769/Device-drivers-in-user-space
http://www.enea.com/Documents/Resources/Whitepapers/Enea-User-Space-Drivers-in-Linux_Whitepaper_2013.pdf

so is there something that elaborates on both the pros and cons of
doing this? in particular, are there any nice examples of this that
can be downloaded, built and played with? thanks muchly.

rday

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
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