Robert Day proposed a couple of new kernel code maturity configuration options for tagging code as either "deprecated" or "obsolete". He referenced earlier confusion around the attempt to remove devfs [story] in which it wasn't clear on the current state and future plans for the code. He explained, "using deprecated code is still technically fine, but using obsolete code should be something that raises a red flag of some kind." Aside from a little confusion between the differences in definition between these two words, general feedback was positive. H. Peter Anvin supported the patch, "if nothing else, it gives some middle-of-the-roadness to the continual 'to remove or not to remove' debate." Robert also noted that the "deprecated" flag would be a useful sanity check when building a kernel, "this would seem to be a quick and dirty way to prune anything that is *supposed* to be obsolete from the build, to make sure you're not picking up dead code by accident." The patch includes definitions of these two states:

"Code that is tagged as 'deprecated' is officially still available for use but will typically have already been scheduled for removal at some point, so it's in your best interests to start looking for an alternative.

"Code that is tagged as 'obsolete' is officially no longer supported and shouldn't play a part in any normal build, but those features might still be available if you absolutely need access to them. You are *strongly* discouraged from continuing to depend on obsolete code on an ongoing, long-term basis."