Support for drivers in user space [LWN.net]

Support for drivers in user space

Posted Sep 7, 2006 18:56 UTC (Thu) by mycroft (guest, #40381)
Parent article: Support for drivers in user space

Very interesting read. You might also consider the other reasons for wanting a user level device driver (ULDD):

o Improved development time
o Fault isolation/recovery
o Isolation from the linux kernel may make it more
portable, especially if similar support can be made
to other OS's.

In regards to handling interrupts. Have you looked at Peter Chubb's
work on the Gelato project (www.gelato.org) with ULDD's? He has a
good idea for handling interrupts from user mode.

This interest in ULDD's is good to see as it is an area of
interest for me.

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benefits of user space

Posted Sep 8, 2006 3:11 UTC (Fri) by pjm (subscriber, #2080) [Link]

Indeed: I'd have thought that one of the primary reasons for userspace drivers is for the greater fault isolation. Many device drivers have noticeably lower quality code and tend to have more bugs per line of code than the rest of the kernel. Moving to userspace (separate address space, more familiar programming environment) reduces the harm that can be done: buggy userspace device drivers can still bring down the system, but there's less opportunity for bugs to silently corrupt unrelated parts of memory (for example).

(Device drivers tend to be written by people with knowledge of / access to the device in question, and are often not regular kernel developers. The limited pool of people with access to a particular device means that fewer eyes pass over the code, and in particular that fewer exceptionally good programmers look at the code as some of the rest of Linux.)