diff options
Diffstat (limited to 'docs/PORTING')
| -rw-r--r-- | docs/PORTING | 135 |
1 files changed, 0 insertions, 135 deletions
diff --git a/docs/PORTING b/docs/PORTING deleted file mode 100644 index d04f3b4f5..000000000 --- a/docs/PORTING +++ /dev/null @@ -1,135 +0,0 @@ -Some notes to help future porters. Replace 'ARCH' with whatever arch -you are hacking on. - -==================== -=== Config Files === -==================== -- create extra/Configs/Config.ARCH - See the other arch files for some good examples. powerpc/sparc/alpha - should be pretty simple templates. -- add ARCH to the 'Target Architecture' list in extra/Configs/Config.in -- Initially you will want to disable shared libraries, since making - the shared library loader work requires you first have basic architecture - support working. Thus you should add ARCH_HAS_NO_SHARED and - ARCH_HAS_NO_LDSO to Config.ARCH's TARGET_ARCH - -==================== -=== libc sysdeps === -==================== -(note: if glibc has already been ported to your arch, you can usually just - copy a lot of files from them rather than coding from scratch) -- create libc/sysdeps/linux/ARCH -- copy Makefile and Makefile.arch from libc/sysdeps/linux/i386/ -- set CSRC and SSRC to nothing in Makefile.arch for now - -- create crt1.S which defines the _start function ... you will probably want - to clear the frame pointer to make gdb happy, and then you will want to call - the funcion __uClibc_main() which takes these parameters: - __uClibc_main(main(), argc, argv, _init(), _fini()) - Initially if you wish to make things easier on yourself, you can disable the - UCLIBC_CTOR_DTOR option and just set the init/fini arguments to NULL. - glibc generally stores this function in libc/sysdeps/ARCH/elf/start.S - -- create these additional files in ARCH/bits/ - - (template versions can be found in common/bits/ for you to tweak) - endian.h fcntl.h setjmp.h stackinfo.h uClibc_arch_features.h wordsize.h - - kernel_types.h should be created based upon linux asm-ARCH/posix_types.h - - copy linux asm-ARCH/stat.h to bits/kernel_stat.h - - create syscalls.h based upon linux's unistd.h / glibc's sysdeps.h ... really - you just want to define the _syscall[0-6] macros. It is important that - these syscalls should be PIC safe (or you should provide a PIC and non-PIC - version) if you wish to properly support shared libraries. - -- at this point, you should have enough to generate a working HELLO WORLD - static binary - -- if you want UCLIBC_CTOR_DTOR support, you will need to create crti.S and - crtn.S files which define function prologues/epilogues. - -- for a more stable static port, you will need to create these files (and - update the Makefile.arch values accordingly) - __longjmp bsd-_setjmp bsd-setjmp brk clone setjmp syscall vfork - usually these are written in assembler, but you may be able to cheat and - write them in C ... see other ports for more information - -==================== -=== pthread deps === -==================== - -TODO: nptl / linuxthreads / linuxthreads.old - -==================== -=== ldso sysdeps === -==================== -- elf.h - presumably you've already taught binutils all about the random ELF - relocations your arch needs, so now you need to make sure the defines exist - for uClibc. make sure the EM_### define exists and all of the R_###_### - reloc defines. - -- enable ldso/shared options in your extra/Configs/Config.ARCH file -- you will need to create the following files in ldso/ldso/ARCH/ - dl-debug.h dl-startup.h dl-syscalls.h dl-sysdep.h elfinterp.c resolve.S - -- dl-debug.h: define string versions of all the relocations of your arch in the - _dl_reltypes_tab array ... the index should match the actual reloc type, so - if the value of say R_X86_64_PC16 is 13, then "R_X86_64_PC16" better be at - index 13 of the array - -- dl-startup.h: - - define the _start function which should call _dl_start which takes just one - parameter ... a pointer to argc (usually on the stack) - glibc stores this function in libc/sysdeps/ARCH/dl-machine.h as RTLD_START - - define the GET_ARGV() macro which calculates the value of argv based upon - the parameter passed to _dl_start (usually it's simply just ARGS+1) - - define PERFORM_BOOTSTRAP_RELOC() macro which will handle just the relocs - that the ldso itself will generate - -- dl-syscalls.h: - if you wrote your bits/syscalls.h file correctly in the libc step above, you - can simply copy this file from another arch and be done ... otherwise you - will have to define the syscall[0-6] macros again, but this time setting - _dl_errno instead of just errno - -- dl-sysdep.h: - misc cruft goes in here ... you want to: - - either define or undefine ELF_USES_RELOCA - - define the INIT_GOT macro - - define MAGIC1 to the EM_### value your ELF arch uses - - define ELF_TARGET to a string name for your arch - - define the do_rem() macro - - define misc ALIGN macro's - - define elf_machine_type_class() macro - - define the inline functions elf_machine_dynamic, elf_machine_load_address, - and elf_machine_relative - glibc stores a bunch of these values in libc/sysdeps/ARCH/dl-machine.h - -- elfinterp.c: - define all the relocation functions ... it's best if you just copy from - another arch which uses the same type of relocations (REL or RELA) and - start from there. - -- resolve.S: - front end of lazy relocation ... define the _dl_linux_resolve symbol which - is called by a PLT entry which has yet to be setup ... you will want to: - - set up arguments for _dl_linux_resolver() - - call _dl_linux_resolver() - - clean up after call - - jump to function address now stored in PLT - glibc stores this function in libc/sysdeps/ARCH/dl-trampoline.S - -- utils/ldd.c - if you want support for ldso cache files (spoiler: you do), - then you'll need to teach ldd a little. generally, the fallback code - should be smart and "just work", but you should be explicit. just pop - it open and add an appropriate ifdef for your arch and set MATCH_MACHINE() - and ELFCLASSM. there are plenty examples and you're (hopefully) smart. - -==================== -=== Misc Cruft === -==================== -- MAINTAINERS - presumably you're going to submit this code back to mainline - and since you're the only one who cares about this arch (right now), you - should add yourself to the toplevel MAINTAINERS file. do it. |