Re: Generating an ELF file with PT_NOTE before PT_LOAD

[Mike Crowe <mac at mcrowe dot com>]

On Thursday 22 February 2018 at 10:19:21 +0100, Andreas Schwab wrote:
> On Feb 21 2018, Mike Crowe <mac@mcrowe.com> wrote:
> 
> > On Wednesday 21 February 2018 at 16:58:39 +0100, Andreas Schwab wrote:
> >> On Feb 21 2018, Mike Crowe <mac@mcrowe.com> wrote:
> >> 
> >> > --8<--
> >> > #!/bin/sh
> >> > set -e
> >> > dd if=/dev/zero of=binary bs=1M count=1
> >> > objcopy -I binary -O elf32-i386 -B i386 binary text.o
> >> >
> >> > gcc -c -m32 -x assembler - -o note.o <<EOF
> >> >     .section ".note.my-version", ""
> >> 
> >> I think you need to make that section allocated, otherwise the linker
> >> will always place it after the other allocated sections.
> >
> > I think that I've done that by changing the last line you quoted to:
> >
> >     .section ".note.my-version", "a"
> >
> > Now the script warns, but doesn't seem to do anything else differently.
> > Here's the new output:
> >
> > --8<--
> > ld.bfd: out.elf: warning: allocated section `.note' not in segment
> 
> Does it help to put the .note section also inside the load segment?

I think that I've done that by modifying the script to say:

--8<--
cat > test.lds <<EOF
SECTIONS
{
    .note : {
        *(.note.my-version)
    } :note
    .text : {
    	*(.note.my-version)
        *(.data)
    } :load
    _end = .;
}
PHDRS
{
  note PT_NOTE;
  load PT_LOAD;
}
EOF
-->8--

But it doesn't seem to have helped. The output is now:

--8<--
ld.bfd: out.elf: warning: allocated section `.note' not in segment

Elf file type is EXEC (Executable file)
Entry point 0x20
There are 2 program headers, starting at offset 52

Program Headers:
  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  NOTE           0x100074 0x00000000 0x00000000 0x00020 0x00020 R   0x4
  LOAD           0x000074 0x00000020 0x00000020 0x100000 0x100000 R E 0x1

 Section to Segment mapping:
  Segment Sections...
   00     .note
   01     .text
-->8--

Thanks.

Mike.