[Bug ld/5522] Section contents partially overwritten with zero

[hjl at lucon dot org]

------- Additional Comments From hjl at lucon dot org  2007-12-27 01:12 -------
There are

  /* An instruction to the linker to not output the section
    even if it has information which would normally be written.  */
#define SEC_NEVER_LOAD 0x200

`NOLOAD'
     The section should be marked as not loadable, so that it will not
     be loaded into memory when the program is run.

        case noload_section:
          flags &= ~SEC_LOAD;
          flags |= SEC_NEVER_LOAD;

What happens when an output section is marked as NOLOAD? From the linker
manual, it seems implies that the output section won't be loaded into
memory, but may still occupy space in file. But linker comments say that
the output section is ignored. But we got

  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            00000000 000000 000000 00      0   0  0
  [ 1] .text             PROGBITS        00400090 000090 00058c 00  AX  0   0 16
  [ 2] .bs.required      PROGBITS        0040061c 00061c 000004 00      0   0  1
  [ 3] .bs.server.name   PROGBITS        00400620 000620 00000e 00   W  0   0  1
  [ 4] .bs.server.servic PROGBITS        0040062e 00062e 000017 00   W  0   0  1
  [ 5] .rodata           NOBITS          00400645 00061c 000003 00  WA  0   0  1
  [ 6] .trampoline       PROGBITS        00401000 000645 0004c0 00   X  0   0  1
  [ 7] .data.server      NOBITS          00400648 00061c 00000c 00  WA  0   0  1
  [ 8] .stab             PROGBITS        00000000 000b08 0018b4 0c      9   0  4
  [ 9] .stabstr          STRTAB          00000000 0023bc 007404 00      0   0  1
  [10] .shstrtab         STRTAB          00000000 0097c0 000081 00      0   0  1
  [11] .symtab           SYMTAB          00000000 009a4c 001da0 10     12 419  4
  [12] .strtab           STRTAB          00000000 00b7ec 000ed0 00      0   0  1
./ld-next -m elf_i386 -o next -T bss.lds attention.o libbss.a 
objdump -s -j .bs.server.name attention.o

attention.o:     file format elf32-i386

Contents of section .bs.server.name:
 0000 41747465 6e74696f 6e536967 6e00      AttentionSign.  
objdump -s -j .bs.server.name next

next:     file format elf32-i386

Contents of section .bs.server.name:
 400620 00000000 00000000 6e536967 6e00      ........nSign.  
objdump -s -j .data.server attention.o

attention.o:     file format elf32-i386

Contents of section .data.server:
 0000 00000000 00000000 00000000           ............

That is linker writes out the .data.server section marked with SHT_NOBITS
and overrides the next section.





-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=5522

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