Re: ld -Ttext 0x80000 causes ld.so segfault on ppc-unknown-linux-gnu

[Anton Ertl <anton at a0 dot complang dot tuwien dot ac dot at>]

Ian Lance Taylor wrote:
> -Ttext is documented to set the start of the .text section.  It's not
> very useful for ELF.  For ELF, we might want to invent a new option,
> which somehow sets the address of the entire text segment.

I don't know ELF enough to know what the difference between sections
and segments is, but the documentation for ld-2.9.1, as well as 000705
says that -Ttext sets the start address of the text segment.

Also, with ld-2.9.5 on ppc-unknown-linux-gnu -Ttext seems to influnce
the start address of the following sections: .text .init .fini .rodata
.sdata2, and, probably indirectly, .data etc:

[samhain:/bigben/home/anton/tmp:1004] gcc -O -Xlinker -Ttext -Xlinker 0x80000 xx
x.c
[samhain:/bigben/home/anton/tmp:1005] objdump -h

a.out:     file format elf32-powerpc

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .text         000001e0  00080000  00080000  00010000  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  1 .interp       0000000d  10000114  10000114  00020114  2**0
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  2 .note.ABI-tag 00000020  10000130  10000130  00020130  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  3 .hash         00000034  10000150  10000150  00020150  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  4 .dynsym       00000080  10000184  10000184  00020184  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  5 .dynstr       0000007d  10000204  10000204  00020204  2**0
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  6 .gnu.version  00000010  10000282  10000282  00020282  2**1
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  7 .gnu.version_r 00000020  10000294  10000294  00020294  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  8 .rela.plt     0000003c  100002b4  100002b4  000202b4  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  9 .init         00000028  000801e0  000801e0  000101e0  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
 10 .fini         00000020  00080208  00080208  00010208  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
 11 .rodata       00000024  00080228  00080228  00010228  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
 12 .sdata2       00000000  0008024c  0008024c  0001024c  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
 13 .data         00000020  00090250  00090250  00010250  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 14 .eh_frame     00000004  00090270  00090270  00010270  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 15 .dynamic      000000a0  00090274  00090274  00010274  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 16 .ctors        00000008  00090314  00090314  00010314  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 17 .dtors        00000008  0009031c  0009031c  0001031c  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 18 .got          00000010  00090324  00090324  00010324  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 19 .sdata        00000000  00090334  00090334  00010334  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 20 .sbss         00000000  00090334  00090334  00010334  2**0
                  ALLOC
 21 .plt          00000084  00090334  00090334  00010334  2**2
                  ALLOC, CODE
 22 .bss          00000030  000903c0  000903c0  0001033c  2**2
                  ALLOC
 23 .stab         00000744  00000000  00000000  000202f0  2**2
                  CONTENTS, READONLY, DEBUGGING
 24 .stabstr      00001342  00000000  00000000  00020a34  2**0
                  CONTENTS, READONLY, DEBUGGING
 25 .comment      0000013e  000903f0  000903f0  00021d76  2**0
                  CONTENTS, READONLY

My expectation wrt -Ttext is that the resulting binary works, and that
the executable code is behind, but not too far from the address given.
I.e., it should work like the ld script I created by setting
TEXT_START_ADDR in ld/emulparams/elf32ppc*.sh and running make.

- anton