JMPADD reloc in MIPS ECOFF file

JMPADD reloc in MIPS ECOFF file

[Alexander Voropay]

Hi!

 Can anyone help me ? How to force MIPS binutils to emit an
ECOFF object file with JMPADDR relocs ?

 I have an old MIPS-based X-Terminal, Tektronix TekXPress 338.
This device is based on the old MIPS VxWorks 5.0.4 (WIND 2.0 kernel).
I'm tryind to build an application with GCC/binutils.

 As it is known, the VxWorks applications is just a "half-linked"
.o objects with undefined externals. The VxWorks itself
is a sort of huge ".so library". Never VxWorks versions are
using ELF, but my old version uses ECOFF.

http://tekxp-linux.hopto.org/pmwiki/pmwiki.php/Software/Toolchains

 Unfortunately, built-in VxWork's `ld` accepts only REFHI, REFLO
and JMPADDR relocs but does not support for GPREL relocs while
the modern binutils emits GPREL.

 I'm using a `objcopy` to convert from ELF to ECOFF.

 How to make an ECOFF with JMPADDR relocs ?


$ mips-linux-gcc -O2 -mips1 -mno-half-pic -fno-pic -mno-abicalls -ffreestanding  -c hellovx.c -o hellovx.elf
$ mips-linux-objcopy -O ecoff-bigmips hellovx.elf hellovx.ecoff

$ mips-linux-objdump -x hellovx.elf
...
RELOCATION RECORDS FOR [.text]:
OFFSET   TYPE              VALUE
00000004 R_MIPS_HI16       hello
00000008 R_MIPS_LO16       hello
00000014 R_MIPS_26         write

$ mips-linux-objdump -x hellovx.ecoff
...
RELOCATION RECORDS FOR [.text]:
OFFSET           TYPE              VALUE
0000000000000004 REFLO             hello
0000000000000008 GPREL             hello
0000000000000014 REFHI             write
...

 The R_MIPS_LO16  becames GPREL, but R_MIPS_26 --> REFHI  ???
How it is possible ?

 The binutils is  2.13.90.0.16 .

--
-=AV=-

Re: JMPADD reloc in MIPS ECOFF file

[Nick Clifton]

Hi Alexander,

> Can anyone help me ? How to force MIPS binutils to emit an
> ECOFF object file with JMPADDR relocs ?
> 
> As it is known, the VxWorks applications is just a "half-linked"
> .o objects with undefined externals. The VxWorks itself
> is a sort of huge ".so library". Never VxWorks versions are
> using ELF, but my old version uses ECOFF.

I think that the only way you are going to get what you want is to find 
an old version of the VxWorks toolchain (for MIPS) and use that.

Cheers
   Nick

Re: JMPADD reloc in MIPS ECOFF file

[Alexander Voropay]

Hi!

>> Can anyone help me ? How to force MIPS binutils to emit an
>> ECOFF object file with JMPADDR relocs ?
> I think that the only way you are going to get what you want is to find 
> an old version of the VxWorks toolchain (for MIPS) and use that.

 I've built a binutils-2.15 with a just plain "./configure --target=mips-ecoff"

 This makes a object files with JMPADDR as required by VxWorks loader!



$ /mips/binutils-2.15/binutils/objdump -i
BFD header file version 2.15
ecoff-bigmips
 (header big endian, data big endian)
  mips
ecoff-littlemips
 (header little endian, data little endian)
  mips
...
$ /mips//binutils-2.15/binutils/objdump -x /mips/app/hellovx/test.o

/mips/app/hellovx/test.o:     file format ecoff-bigmips
/mips/app/hellovx/test.o
architecture: mips:3000, flags 0x00000031:
HAS_RELOC, HAS_SYMS, HAS_LOCALS
start address 0x00000000

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .text         00000030  00000000  00000000  000000f0  2**4
                  CONTENTS, ALLOC, LOAD, RELOC, CODE
  1 .rdata        00000010  00000030  00000030  00000120  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  2 .data         00000000  00000040  00000040  00000130  2**4
                  CONTENTS, ALLOC, LOAD, DATA
  3 .bss          00000000  00000040  00000040  00000000  2**4
                  ALLOC
SYMBOL TABLE:
[  0] e 00000000 st 0 sc 0 indx fffff     entry
[  1] e 00000000 st 1 sc 6 indx fffff     printf
[  3] l 00000000 st 5 sc 1 indx fffff     entry

RELOCATION RECORDS FOR [.text]:
OFFSET   TYPE              VALUE
00000004 REFHI             .rdata+0xffffffd0
00000008 REFLO             .rdata+0xffffffd0
00000010 JMPADDR           printf

--
-=AV=-