xref: /xnu-11215.81.4/libkern/kmod/README (revision d4514f0bc1d3f944c22d92e68b646ac3fb40d452)
1*d4514f0bSApple OSS Distributions#
2*d4514f0bSApple OSS Distributions# Subtle combination of files and libraries make up the C++ runtime system for
3*d4514f0bSApple OSS Distributions# kernel modules.  We are dependant on the KernelModule kmod.make and
4*d4514f0bSApple OSS Distributions# CreateKModInfo.perl scripts to be exactly instep with both this library
5*d4514f0bSApple OSS Distributions# module and the libkmod module as well.
6*d4514f0bSApple OSS Distributions#
7*d4514f0bSApple OSS Distributions# If you do any maintenance on any of the following files make sure great
8*d4514f0bSApple OSS Distributions# care is taken to keep them in Sync.
9*d4514f0bSApple OSS Distributions#    extenTools/KernelModule.bproj/kmod.make
10*d4514f0bSApple OSS Distributions#    extenTools/KernelModule.bproj/CreateKModInfo.perl
11*d4514f0bSApple OSS Distributions#    IOKitUser/kmodc++/pure.c
12*d4514f0bSApple OSS Distributions#    IOKitUser/kmodc++/cplus_start.c
13*d4514f0bSApple OSS Distributions#    IOKitUser/kmodc++/cplus_start.c
14*d4514f0bSApple OSS Distributions#    IOKitUser/kmodc/c_start.c
15*d4514f0bSApple OSS Distributions#    IOKitUser/kmodc/c_stop.c
16*d4514f0bSApple OSS Distributions#
17*d4514f0bSApple OSS Distributions# The trick is that the linkline links all of the developers modules.
18*d4514f0bSApple OSS Distributions# If any static constructors are used .constructors_used will be left as
19*d4514f0bSApple OSS Distributions# an undefined symbol.  This symbol is exported by the cplus_start.c routine
20*d4514f0bSApple OSS Distributions# which automatically brings in the appropriate C++ _start routine.  However
21*d4514f0bSApple OSS Distributions# the actual _start symbol is only required by the kmod_info structure that
22*d4514f0bSApple OSS Distributions# is created and initialized by the CreateKModInfo.perl script.  If no C++
23*d4514f0bSApple OSS Distributions# was used the _start will be an undefined symbol that is finally satisfied
24*d4514f0bSApple OSS Distributions# by the c_start module in the kmod library.
25*d4514f0bSApple OSS Distributions#
26*d4514f0bSApple OSS Distributions# The linkline must look like this.
27*d4514f0bSApple OSS Distributions#    *.o -lkmodc++ kmod_info.o -lkmod
28*d4514f0bSApple OSS Distributions#
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