Stablity is a chimera
LWN has yet another thread on kernel stability. Some people would like to be able to install new drivers on old kernels. This is the mirror image of something also often requested: being able to use old (typically binary) drivers on new kernels.
Satisfying both at once requires not just backward- but also forward compatibility: the interfaces between interchangeable parts of the kernel must not change *at all* within a stability window. This is very constraining to development, and since people would like to use years-old binaries the window is very large. So in fact this is possible, if we define the stability window to be exactly one kernel release: anything that works against 2.4.20 will continue to work against 2.4.20 forever.
More generally: everyone would like a stable series that lets them get the bug fixes they care about, but without any unnecessary changes. The problem is that different people have different requirements for what is allowed into the stable kernel series. Some people really need support for some new hardware, but to everyone else that's unnecessary churn. Some people want nothing but security fixes; some people want security and bug fixes; some people want new drivers but no core kernel changes; some people need scheduler changes to run their workload effectively.
It is fundamentally impossible to reconcile all of these changes; therefore the optimal approach is to develop the mainstream in the most efficient way possible, and let people fork stable branches as they want. If you want to build a branch which has only bug and security fixes and nothing more then you can.
posted Fri 17 Dec 2004 in /software/linux-kernel | link
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