xref: /xnu-10002.61.3/libkern/kmod/README (revision 0f4c859e951fba394238ab619495c4e1d54d0f34)
1*0f4c859eSApple OSS Distributions#
2*0f4c859eSApple OSS Distributions# Subtle combination of files and libraries make up the C++ runtime system for
3*0f4c859eSApple OSS Distributions# kernel modules.  We are dependant on the KernelModule kmod.make and
4*0f4c859eSApple OSS Distributions# CreateKModInfo.perl scripts to be exactly instep with both this library
5*0f4c859eSApple OSS Distributions# module and the libkmod module as well.
6*0f4c859eSApple OSS Distributions#
7*0f4c859eSApple OSS Distributions# If you do any maintenance on any of the following files make sure great
8*0f4c859eSApple OSS Distributions# care is taken to keep them in Sync.
9*0f4c859eSApple OSS Distributions#    extenTools/KernelModule.bproj/kmod.make
10*0f4c859eSApple OSS Distributions#    extenTools/KernelModule.bproj/CreateKModInfo.perl
11*0f4c859eSApple OSS Distributions#    IOKitUser/kmodc++/pure.c
12*0f4c859eSApple OSS Distributions#    IOKitUser/kmodc++/cplus_start.c
13*0f4c859eSApple OSS Distributions#    IOKitUser/kmodc++/cplus_start.c
14*0f4c859eSApple OSS Distributions#    IOKitUser/kmodc/c_start.c
15*0f4c859eSApple OSS Distributions#    IOKitUser/kmodc/c_stop.c
16*0f4c859eSApple OSS Distributions#
17*0f4c859eSApple OSS Distributions# The trick is that the linkline links all of the developers modules.
18*0f4c859eSApple OSS Distributions# If any static constructors are used .constructors_used will be left as
19*0f4c859eSApple OSS Distributions# an undefined symbol.  This symbol is exported by the cplus_start.c routine
20*0f4c859eSApple OSS Distributions# which automatically brings in the appropriate C++ _start routine.  However
21*0f4c859eSApple OSS Distributions# the actual _start symbol is only required by the kmod_info structure that
22*0f4c859eSApple OSS Distributions# is created and initialized by the CreateKModInfo.perl script.  If no C++
23*0f4c859eSApple OSS Distributions# was used the _start will be an undefined symbol that is finally satisfied
24*0f4c859eSApple OSS Distributions# by the c_start module in the kmod library.
25*0f4c859eSApple OSS Distributions#
26*0f4c859eSApple OSS Distributions# The linkline must look like this.
27*0f4c859eSApple OSS Distributions#    *.o -lkmodc++ kmod_info.o -lkmod
28*0f4c859eSApple OSS Distributions#
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