On Sat, 28 Apr 2012, David Laight wrote:
This mechanism only works for modules that are "separate" from the kernel (loaded via "boot" or from "filesys"). "builtin" modules still need to use the link_set mechanism.Shouldn't be that hard to put the contructor list address into a link_set - that would make it easy to get them called for 'built in' modules. Thinks a bit further... Have each module define a snall structure that contains (say): - it's name - the address of a list of modules it depends on - the address of its constructors - the address of its destructios Then you can control the order of initialisers as well.
The problem (at least, in the net80211 module case) is to not require any single source file to know the entire set of constructors. There are various crypto-algorithms which may or may not be included in the final module, and the contructors "register" their presence. The link_set mechanism solves this in the non-MODULE case by creating a user-defined program section to which any source file can contribute. But the symbols that point to the start and end address of the link-set program section aren't accessible in the MODULE case.
The .ctors/.dtors approach works fine for the MODULE case, since the program section is specific to the module itself. But this doesn't work in the built-into-kernel case, since all constructors for all modules (and other, non-module code) would get intermingled without any control over ordering or segregation into a single kernel-wide section.
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