ELF Symbol Name Length
Category: unlimited. The ELF spec has no real (artificial) symbol name limitation. It only restricts offsets in string table by 4 bytes. And gcc/gdb are consequent: they also introduce no artificial limitation.
Of course, resolving dynamic linked object requires hashing and strcmp'ing these symbol names. Especially larger projects with lots of symbols will suffer from this (you may notice this for C++ symbols because of namespace bloat).