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Re: Adding a NOTE section after a copy ..
- From: Roland McGrath <roland at redhat dot com>
- To: elfutils-devel at lists dot fedorahosted dot org
- Date: Wed, 21 Oct 2009 22:46:58 -0700
- Subject: Re: Adding a NOTE section after a copy ..
You cannot add an SHF_ALLOC section to an already-final (non-ET_REL) ELF
file without doing a lot more work. If you want a non-allocated section
created with the compiler, you have to play some games with asm () to get
the section flags right. For adding a simple string or binary blob, it is
easier to write or generate assembly source where you write exactly the
section directive you want (.section .note.foo, "", @note).
If you use ELF_F_LAYOUT (which you must unless you recompute the phdrs
too), then you have to set sh_offset manually in your new section.
Indeed you do not have to adjust e_shnum; that is automatic in elf_update
after you have used elf_newscn. Of course, you do need to add your
section's name to .shstrtab.
You may find it easier to write a script using objcopy --add-section
(binutils) rather than writing your own tool with libelf.
Thanks,
Roland