[Bug ld/11542] New: ld -r generates R_X86_64_NONE

[mjw at redhat dot com]

This comes up when building a kernel module debuginfo. A .rela.debug_info
section contains R_X86_64_NONE relocations. It is for a symbol in a section
called .discard, which the linker script discards. It seems that ld -r should
eat the reloc rather than leave *_NONE.

Reproducer based on kernel module build:

$ cat > foo.c
int here, there __attribute__ ((section (".discard")));

$ cat > module-common.lds
/*
 * Common module linker script, always used when linking a module.
 * Archs are free to supply their own linker scripts.  ld will
 * combine them automatically.
 */
SECTIONS {
        /DISCARD/ : { *(.discard) }
}

$ ld -r -o foo2.o module-common.lds foo.o ld: warning: module-common.lds
contains output sections; did you forget -T?

$ ld -r -o foo2.o -T module-common.lds foo.o
$ readelf -r foo2.o

Relocation section '.rela.debug_info' at offset 0x618 contains 11 entries:
  Offset          Info           Type           Sym. Value    Sym. Name + Addend
000000000006  00040000000a R_X86_64_32       0000000000000000 .debug_abbrev + 0
00000000000c  00080000000a R_X86_64_32       0000000000000000 .debug_str + b
000000000011  00080000000a R_X86_64_32       0000000000000000 .debug_str + 38
000000000015  00080000000a R_X86_64_32       0000000000000000 .debug_str + 6
000000000019  000100000001 R_X86_64_64       0000000000000000 .text + 0
000000000021  000100000001 R_X86_64_64       0000000000000000 .text + 0
000000000029  00060000000a R_X86_64_32       0000000000000000 .debug_line + 0
00000000002e  00080000000a R_X86_64_32       0000000000000000 .debug_str + 33
00000000003b  000c00000001 R_X86_64_64       0000000000000004 here + 0
00000000004b  00080000000a R_X86_64_32       0000000000000000 .debug_str + 0
000000000058  000000000000 R_X86_64_NONE                        0000000000000000

Relocation section '.rela.debug_pubnames' at offset 0x720 contains 1 entries:
  Offset          Info           Type           Sym. Value    Sym. Name + Addend
000000000006  00050000000a R_X86_64_32       0000000000000000 .debug_info + 0

-- 
           Summary: ld -r generates R_X86_64_NONE
           Product: binutils
           Version: 2.20
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ld
        AssignedTo: unassigned at sources dot redhat dot com
        ReportedBy: mjw at redhat dot com
                CC: bug-binutils at gnu dot org


http://sourceware.org/bugzilla/show_bug.cgi?id=11542

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