super-strip

> Whereas, with ELF – if you want to add a new feature, do you add it as a new program table entry type (PT_), or a new note type (NT_), or a separate note section (SHT_NOTE)? It won't be a note section since ELF binaries don't need to have any sections. You can remove all section headers from an existing ELF binary and it'll still work (sstrip [https://github.com/aunali1/super-strip - not sure the one in ELFkickers is the same thing] does this). Program headers define how & where to load things, notes are for small metadata. Is your point that section headers do generally exist in ELF files, even though they're not necessary? I do agree that this "double indexing" between PHs and SHs is pretty weird and a bit odd.

The approach taken there is unfortunately not correct. The existence of sections (and section headers) is completely optional for ELF files; you can have valid executables and libraries without them. `sstrip` [https://github.com/aunali1/super-strip] can be used to generate such files. The correct approach is to process the program headers and find the tail end of anything referenced in PT_LOAD as well as from DT_DYN items. You can combine that with a section based approach; if the file has debug information it won't be covered by program headers and you'd end up cutting it off if going purely by program headers. However, this is technically optional while the program header based approach is really required.

I think large chunk of it is from dynamic linker, rather than glibc. At least that appear to be the case according to "file a.out". Adding "-static" option seems to prevent that: $ gcc -Wall -s -nostdlib tiny.o; wc -c a.out 12780 a.out $ gcc -Wall -s -nostdlib tiny.o -static $ wc -c a.out 4304 a.out Bulk of what remains is page-size alignment. Linux works with 4KB pages: $ getconf PAGESIZE 4096 ...so it makes sense that gcc (ld, really) aligns to that. But we can dial it down: $ gcc -Wall -s -nostdlib tiny.o -static \ -Wl,-zmax-page-size=64; wc -c a.out 400 a.out ...and a bit more could be shaven by dropping Build ID: $ strip -R .note.gnu.build-id a.out; wc -c a.out 344 a.out This wonderful piece of software: https://github.com/aunali1/super-strip seem to find more things to remove, although not sure what w