Linking non-PIC modules with PIC modules for MIPS SVR4.2MP

["Kai Ruottu" <kai_ruottu at mbnet dot fi>]

On NEC's EWS4800 the provided 'shared' libs in '/usr/abiccs/lib' are partly made
of non-PIC modules ('crt*.o', some separate modules inside 'libc.so') and of real
PIC-mode shared libs.  My problem is to produce a cross-toolkit for this weird
'mips-nec-sysv4.2MP' stuff using the GNU binutils...

The native linker can mix the modules using wrapper-switches '-Znocount'
and '-Zcount' around the 'non-PIC' stuff :

---------
 /usr/local/lib/gcc-lib/mips-nec-sysv4.2MP/2.95.2/collect2 -dy -o chap26_9
 -Znocount /usr/abiccs/lib/crt1.o /usr/abiccs/lib/crti.o -Zcount
 -L/usr/local/lib/gcc-lib/mips-nec-sysv4.2MP/2.95.2
 -L/usr/local/mips-nec-sysv4.2MP/lib
 -L/usr/abiccs/bin -L/usr/abiccs/lib -L/usr/local/lib
 /var/tmp/ccjzUkrt.o -lstdc++ -lm
 -lgcc
 -Znocount -lc /usr/abiccs/lib/crtn.o /usr/abiccs/lib/values-Xt.o -Zcount
 -lgcc
---------

but trying the '-Bstatic' and '-Bdynamic' for the same 'non-PIC'/'PIC'-mixing
with GNU ld doesn't work.  It tells that it still cannot mix the PIC- and non-PIC
stuff...   Is there any way to do this mixing?

The seen workarounds are to use the fully-PIC shared '/usr/lib/libc.so.1'
as the C-library to link with at the link-time and to try to reverse-engineer the
'crt*.o' stuff and to duplicate them as 'PIC'-mode modules....

When trying 'free crt*.o's made from a modified 'start.c' from glibc etc., resulted
to the situation that the linked C programs (like cross-built native binutils-2.11.2)
seem to work fine, but all the C++ programs silently die...   BTW, the simple tried
C++ tests seem to need only the 'modff()' from the separate non-PIC modules
inside the original 'libc.so'. Both newlib and glibc-2.x give the 's_modf(f).c' for
replacing the original...

The 'free crt1.o' tried was originally tested to work for another 'mips-sysv4.2', which
was using purely PIC-stuff everywhere.  But it has missing some calls to some 
routines like 'zeromem()' in the original non-PIC 'crt1.o'.  This might cause the C++
programs to die, so I would like to try to better it...

Here comes the problem with 'objdump -d'...  It doesn't seem to use the symbol
table in the module for anything... The called functions and data addresses are
named only as '0 <_start>' and '0x0' in the disassembly although the symbol table
should have some connection to the code :

H:\usr\local\mips-nec-sysv4.2MP\lib\non-pic>..\..\bin\objdump -d crt1.o

crt1.o:     file format elf32-tradbigmips

Disassembly of section .text:

00000000 <_start>:
   0:   3c1c0000        lui     gp,0x0
   4:   279c0000        addiu   gp,gp,0
   8:   27bdffe0        addiu   sp,sp,-32
   c:   afbf0018        sw      ra,24(sp)
  10:   3c040000        lui     a0,0x0
  14:   afa2001c        sw      v0,28(sp)
  18:   0c000000        jal     0 <_start>   <--- What is the function called ?
  1c:   24840000        addiu   a0,a0,0
  20:   8fa2001c        lw      v0,28(sp)
  24:   00000000        nop
  28:   10400003        beqz    v0,38 <_start+0x38>
  2c:   00000000        nop
  30:   0c000000        jal     0 <_start>   <--- What is the function called ?
  34:   00402021        move    a0,v0
  38:   3c040000        lui     a0,0x0
  3c:   0c000000        jal     0 <_start>   <--- What is the function called ?
  40:   24840000        addiu   a0,a0,0
  44:   0c000000        jal     0 <_start>   <--- What is the function called ?
  48:   00000000        nop
  4c:   8fa40020        lw      a0,32(sp)
  50:   27a50024        addiu   a1,sp,36
  54:   24a60004        addiu   a2,a1,4
  58:   00041080        sll     v0,a0,0x2
  5c:   00c23021        addu    a2,a2,v0
  60:   3c010000        lui     at,0x0	<--- Some address loaded
  64:   ac260000        sw      a2,0(at)
  68:   3c010000        lui     at,0x0	<--- Some address loaded
  6c:   ac240000        sw      a0,0(at)
  70:   3c010000        lui     at,0x0	<--- Some address loaded
  74:   ac250000        sw      a1,0(at)
  78:   0c000000        jal     0 <_start>   <--- Some function called
  7c:   afa0001c        sw      zero,28(sp)
  80:   3c040000        lui     a0,0x0	 <--- Some address loaded
  84:   3c050000        lui     a1,0x0	 <--- Some address loaded
  88:   3c060000        lui     a2,0x0	 <--- Some address loaded
  8c:   8c840000        lw      a0,0(a0)
  90:   8ca50000        lw      a1,0(a1)
  94:   8cc60000        lw      a2,0(a2)
  98:   0c000000        jal     0 <_start>   <--- Some function called
  9c:   00000000        nop
  a0:   0c000000        jal     0 <_start>   <--- Some function called
  a4:   00402021        move    a0,v0
  a8:   0000000d        break
  ac:   03e00008        jr      ra
  b0:   00000000        nop

000000b4 <__trapuv>:
  b4:   24080800        li      t0,2048
  b8:   44c8f800        ctc1    t0,ra
  bc:   03e00008        jr      ra
  c0:   00000000        nop

000000c4 <_mcount>:
  c4:   27bd0008        addiu   sp,sp,8
  c8:   03e00008        jr      ra
  cc:   0020f821        move    ra,at

H:\usr\local\mips-nec-sysv4.2MP\lib\non-pic>..\..\bin\objdump -t crt1.o

crt1.o:     file format elf32-tradbigmips

SYMBOL TABLE:
00000000 l    df *ABS*  00000000 crt1.o
00000000 l    d  .reginfo       00000000
00000000 l    d  .text  00000000
00000000 l    d  .note  00000000
00000000 l    d  *ABS*  00000000
00000000 l    d  *ABS*  00000000
00000000 l    d  *ABS*  00000000
00000000 l    d  *ABS*  00000000
00000000 l    d  .comment       00000000
00000000 l    df *ABS*  00000000 ../../src/crt1_text.s
00000000 l     O *ABS*  00000000 STARTFRM
00000000 l    df *ABS*  00000000 /home/sgsenv/usr/abiccs/include/sys/regdef.h
00000000 l    df *ABS*  00000000 /home/sgsenv/usr/src/cmplrs/cc2.20/include/sys/
asm.h
00000000 l    df *ABS*  00000000 ../../src/crt1_data.s
00000000       O *UND*  00000000 _fini
00000000       O *UND*  00000000 main
00007ff0 g     O *ABS*  00000000 _gp
00000000       O *UND*  00000000 _cleanup
00000000 g     F .text  00000000 _start
00000000       O *UND*  00000000 _environ
00000000       O *UND*  00000000 atexit
00000000       O *UND*  00000000 __zeromem
00000004       O *COM*  00000004 __Argc
00000004       O *COM*  00000004 __Argv
00000000       O *UND*  00000000 exit
000000b4 g     F .text  00000000 __trapuv
000000c4 g     F .text  00000000 _mcount
00000000       O *UND*  00000000 _init

Is there any way to see the called function names and the names for the addresses
in the disassembly listing?  Then cloning the current non-PIC 'crt1.o' could be a little
more easy...

  But if looking at the beginning of the startup, it looks having the tinkering
with 'gp' as if it being a PIC-file... But 'readelf -h' claims it isn't...  Is here only a wrong
flag in the file header?

 Anyway if the original non-PIC/PIC stuff could be used with the GNU ld, that would be
best... Is there some way to do this now ?  For instance using the native linker etc. to
convert the non-PIC stuff  into PIC-stuff.  This seems to happen now -- when looking
 with 'objdump -d'  at the natively linked executable, the '_start' etc. stuff there is in
PIC-mode and the whole executable is in the required PIC-mode...

 The access to the target machine has been limited, so just trying all kind of things
isn't that easy....  So I ask it here if someone has tried something equal...

 Many thanks in advance...  Kai