kernel API - a little bit less bias, please
Posted May 19, 2006 8:19 UTC (Fri) by eru
In reply to: kernel API - a little bit less bias, please
Parent article: The Novell Partner Linux Driver Process
I, too find the arguments against a stable source level device interface
unconvincing (while I fully agree that binary ABI is not desirable).
Not wanting to stabilize the device interface made lots of sense when Linux
was young, but now that it is a mainstream system, with lots of people
wanting to use it with lots of different devices, refusal to provide
a stable API and require inclusion of all devices in the kernel
tree will simply not work for much longer. The number of
devices for which open-source support is desirable and possible
is simply too large for that now.
Just the kernel configuration program by itself is beginning to look
like an encyclopedia of computer peripherals, and despite that
many devices for which an open-source driver exists are missing, or
the kernel version of the driver is out-dated.
There are people who
may be willing and able to create a free driver, but are not interested
in updating it forever merely because the kernel interface changes:
Isn't it a pointless activity when the driver works and the hardware
itself has not changed? (might even be out of production, but still
be useful to support for older machines).
A carefully designed source API leaves a lot of flexibility with
respect to the underlying implementation and extension possibilities.
Provide "operators" (which can in reality be macroes or functions),
"opaque" data types whenever possible, and rules about their use. To shake out inwarranted
dependencies, you could even make a point of always putting some changes to the
underlying implementation at each release, so that drivers that use the
abstraction correctly are OK, but misusers break - this would also
weed out attempts to use the source API as a binary ABI!
Incompatible changes cannot of course be always avoided, but they should be
rare, and limited to times when a major version change occurs (like 2.6 to 2.8, if it ever happens).
to post comments)