Re: [PATCH 01/13] objtool: Rewrite hashtable sizing

From: Sami Tolvanen
Date: Thu Jun 10 2021 - 14:52:09 EST


On Thu, Jun 10, 2021 at 11:14 AM Nathan Chancellor <nathan@xxxxxxxxxx> wrote:
> Adding Sami because I am not sure why this patch would have much of an impact
> in relation to LTO. https://git.kernel.org/tip/25cf0d8aa2a3 is the patch in
> question.

It's because LLVM enables -ffunction-sections with LTO, so using .text
section size to estimate the reloc hash table size isn't going to be
accurate, as confirmed by objtool output with --stats:

OBJTOOL vmlinux.o
nr_sections: 141481
section_bits: 17
nr_symbols: 215262
symbol_bits: 17
max_reloc: 24850
tot_reloc: 590890
reloc_bits: 10

Sami