On 3/18/21 8:45 PM, Jisheng Zhang wrote:
Hi, When trying the latest 5.12-rc3 with both LTO_CLANG_THIN and DEBUG_INFO_BTF enabled, I met lots of warnings such as: ... tag__recode_dwarf_type: couldn't find 0x4a7ade5 type for 0x4ab9f88 (subroutine_type)! ftype__recode_dwarf_types: couldn't find 0x4a7ade5 type for 0x4ab9fa4 (formal_parameter)! ... namespace__recode_dwarf_types: couldn't find 0x4a8ff4a type for 0x4aba05c (member)! namespace__recode_dwarf_types: couldn't find 0x4a7ae9b type for 0x4aba084 (member)! ... WARN: multiple IDs found for 'path': 281, 729994 - using 281 WARN: multiple IDs found for 'task_struct': 421, 730101 - using 421 ... then finally get build error: FAILED unresolved symbol vfs_truncate Is this a known issue? Do we need to make DEBUG_INFO_BTF depend on !LTO?
This is a known issue for pahole. pahole does not handle dwarf well generated with LTO. Bill Wendling from google is looking at the issue and I will help look at the issue as well. Since bpf heavily depends
on BTF, at this point, I suggest if you are using bpf, please do not turn on LTO. Or if you build with LTO, just turn off DEBUG_INFO_BTF in your config. Thanks!
pahole version: v1.20 clang version: 11.0 Thanks
