1 Some notes to help future porters. Replace 'ARCH' with whatever arch
7 - create extra/Configs/Config.ARCH
8 See the other arch files for some good examples. powerpc/sparc/alpha
9 should be pretty simple templates.
10 - add ARCH to the 'Target Architecture' list in extra/Configs/Config.in
11 - for now, disable shared libraries
12 add HAVE_NO_SHARED and ARCH_HAS_NO_LDSO to Config.ARCH's HAVE_ELF
17 (note: if glibc has already been ported to your arch, you can usually just
18 copy a lot of files from them rather than coding from scratch)
19 - create libc/sysdeps/linux/ARCH
20 - copy Makefile and Makefile.arch from libc/sysdeps/linux/i386/
21 - set CSRC and SSRC to nothing in Makefile.arch for now
23 - create crt1.S which defines the _start function ... you will probably want
24 to clear the frame pointer to make gdb happy, and then you will want to call
25 the funcion __uClibc_main() which takes these parameters:
26 __uClibc_main(main(), argc, argv, _init(), _fini())
27 for now, you can disable the UCLIBC_CTOR_DTOR option and just set those two
29 glibc stores this function in libc/sysdeps/ARCH/elf/start.S
31 - create these additional files in ARCH/bits/
33 (template versions can be found in common/bits/ for you to tweak)
34 endian.h fcntl.h setjmp.h stackinfo.h uClibc_arch_features.h wordsize.h
36 kernel_types.h should be created based upon linux asm-ARCH/posix_types.h
38 copy linux asm-ARCH/stat.h to bits/kernel_stat.h
40 create syscalls.h based upon linux's unistd.h / glibc's sysdeps.h ... really
41 you just want to define the _syscall[0-6] macros
43 - at this point, you should have enough to generate a working HELLO WORLD
44 static binary (see test/silly/*.c files)
46 - if you want UCLIBC_CTOR_DTOR support, you will need to create crti.S and
47 crtn.S files which define function prologues/epilogues
49 - for a more stable static port, you will need to create these files (and
50 update the Makefile.arch values accordingly)
51 __longjmp bsd-_setjmp bsd-setjmp brk clone setjmp syscall vfork
52 usually these are written in assembler, but you may be able to cheat and
53 write them in C ... see other ports for more information
59 TODO: nptl / linuxthreads / linuxthreads.old
64 - enable ldso/shared options in your extra/Configs/Config.ARCH file
65 - you'll need to create these files in ldso/ldso/ARCH/
66 dl-debug.h dl-startup.h dl-syscalls.h dl-sysdep.h elfinterp.c resolve.S
68 - dl-debug.h: define string versions of all the relocations of your arch in the
69 _dl_reltypes_tab array ... the index should match the actual reloc type, so
70 if the value of say R_X86_64_PC16 is 13, then "R_X86_64_PC16" better be at
74 - define the _start function which should call _dl_start which takes just one
75 parameter ... a pointer to argc (usually on the stack)
76 - define the GET_ARGV() macro which calculates the value of argv based upon
77 the parameter passed to _dl_start (usually it's simply just ARGS+1)
78 - define PERFORM_BOOTSTRAP_RELOC() macro which will handle just the relocs
79 that the ldso itself will generate
82 if you wrote your bits/syscalls.h file correctly in the libc step above, you
83 can simply copy this file from another arch and be done ... otherwise you
84 will have to define the syscall[0-6] macros again, but this time setting
85 _dl_errno instead of just errno
88 misc cruft goes in here ... you want to:
89 - either define or undefine ELF_USES_RELOCA
90 - define the INIT_GOT macro
91 - define MAGIC1 to the EM_### value your ELF arch uses
92 - define ELF_TARGET to a string name for your arch
93 - define the do_rem() macro
94 - define misc ALIGN macro's
95 - define elf_machine_type_class() macro
96 - define the inline functions elf_machine_dynamic, elf_machine_load_address,
97 and elf_machine_relative
98 glibc stores a bunch of these values in libc/sysdeps/ARCH/dl-machine.h
101 define all the relocation functions ... it's best if you just copy from
102 another arch which uses the same type of relocations (REL or RELA) and
106 front end of lazy relocation ... define the _dl_linux_resolve symbol which
107 is called by a PLT entry which has yet to be setup ... you will want to:
108 - set up arguments for _dl_linux_resolver()
109 - call _dl_linux_resolver()
110 - clean up after call
111 - jump to function address now stored in PLT