Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Date | Tue, 7 Apr 2020 00:31:42 +0200 | Subject | Re: libelf-0.175 breaks objtool |
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On Tue, Apr 7, 2020 at 12:16 AM Josh Poimboeuf <jpoimboe@redhat.com> wrote: > > On Mon, Apr 06, 2020 at 11:07:15PM +0200, Arnd Bergmann wrote: > > On Wed, Feb 6, 2019 at 7:32 PM Steven Rostedt <rostedt@goodmis.org> wrote: > > > On Tue, 5 Feb 2019 20:16:11 -0600 Josh Poimboeuf <jpoimboe@redhat.com> wrote: > > > > > > > On Tue, Feb 05, 2019 at 01:38:21PM -0500, Steven Rostedt wrote: > > > > > Just a FYI. > > > > > > > > > > After a recent upgrade in debian testing, I was not able to build the > > > > > kernel. I have a custom build of gcc, so I thought it was strange that > > > > > I was getting something like this (took this from the web, as I don't > > > > > have the error anymore with the work around, and currently doing a full > > > > > build): > > > > > > > > > > objdump: kernel/.tmp_signal.o: unable to initialize decompress status for section .debug_info > > > > > objdump: kernel/.tmp_signal.o: unable to initialize decompress status for section .debug_info > > > > > objdump: kernel/.tmp_signal.o: file format not recognized > > > > > CC arch/x86/kernel/platform-quirks.o > > > > > objdump: arch/x86/kernel/.tmp_ebda.o: unable to initialize decompress status for section .debug_info > > > > > objdump: arch/x86/kernel/.tmp_ebda.o: unable to initialize decompress status for section .debug_info > > > > > objdump: arch/x86/kernel/.tmp_ebda.o: file format not recognized > > > > > objdump: mm/.tmp_swap_slots.o: unable to initialize decompress status for section .debug_info > > > > > objdump: mm/.tmp_swap_slots.o: unable to initialize decompress status for section .debug_info > > > > > objdump: mm/.tmp_swap_slots.o: file format not recognized > > > > > > > > I installed debian testing on a VM, which has libelf 0.175-2, but I > > > > > > Hmm, I only have libelf-0.175 (no -2) > > > > > > > can't recreate. Can you share your config? > > > > > > > > > > It's just a distro config. Ah, I think it's because I'm compiling my > > > own home built gcc. There seems to be an incompatibility with the > > > binutils that I used and with libelf-0.175. If I build with just the > > > distro gcc, it works. > > > > > > Bah, this means I need to recreate my gcc that I use to build my > > > kernels with :-p As I like to control which gcc I use. > > > > I now see the same problem that you reported using the gcc-9 > > toolchain I provide on https://kernel.org/pub/tools/crosstool/. > > > > Do you have any other information that might help me fix it? > > This sounds like an issue I saw before where the toolchain wants to > compress debuginfo (DWARF debug_info sections). The "fix" was to add > '-gz=none' to KCFLAGS. > > But if it's a desired feature then we could probably teach objtool to > deal with it. It ignores DWARF anyway.
This sounds odd, as I have CONFIG_DEBUG_INFO disabled in all my randconfig builds.
It's also odd that I only see the problem in two specific files: arch/x86/realmode/rm/trampoline_64.o (in half of the randconfig builds) and fs/xfs/xfs_trace.o (in only one configuration so far).
With this patch I can avoid the first one, which is unconditionally built with -g (why?):
--- a/arch/x86/realmode/rm/Makefile +++ b/arch/x86/realmode/rm/Makefile @@ -69,7 +69,7 @@ $(obj)/realmode.relocs: $(obj)/realmode.elf FORCE # ---------------------------------------------------------------------------
KBUILD_CFLAGS := $(REALMODE_CFLAGS) -D_SETUP -D_WAKEUP \ - -I$(srctree)/arch/x86/boot + -I$(srctree)/arch/x86/boot -gz=none KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables GCOV_PROFILE := n I'll look at the other one tomorrow.
Arnd
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