From: Tiezhu Yang <yangtiezhu@loongson.cn>
To: Josh Poimboeuf <jpoimboe@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Subject: [QUESTION] How to silence objtool warnings of vmlinux.o
Date: Thu, 14 Aug 2025 10:38:07 +0800 [thread overview]
Message-ID: <8737f2ed-3f4a-3cab-1dd1-55ad50f951e6@loongson.cn> (raw)
When compiling with LLVM and CONFIG_LTO_CLANG is set, there exist the
following objtool warnings after silencing all of the other warnings:
LD vmlinux.o
vmlinux.o: warning: objtool: .head.text+0x0: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x18: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x38: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x3c: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x40: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x44: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x54: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x58: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x6c: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x84: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x94: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x9c: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0xc4: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0xf8: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0xfc: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x104: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x10c: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x11c: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x120: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x124: unreachable instruction
vmlinux.o: warning: objtool: .head.text+0x144: unreachable instruction
vmlinux.o: warning: objtool: kernel_entry+0x0: unreachable instruction
vmlinux.o: warning: objtool: smpboot_entry+0x0: unreachable instruction
All of the above instructions are in arch/loongarch/kernel/head.S,
and there is "OBJECT_FILES_NON_STANDARD_head.o := y" in Makefile
to skip objtool checking for head.o, but OBJECT_FILES_NON_STANDARD
does not work for link time validation of vmlinux.o according to
tools/objtool/Documentation/objtool.txt.
How to silence this kind of objtool warnings?
I appreciate any guidance here.
Thanks,
Tiezhu
next reply other threads:[~2025-08-14 2:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-14 2:38 Tiezhu Yang [this message]
2025-08-14 8:36 ` Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=8737f2ed-3f4a-3cab-1dd1-55ad50f951e6@loongson.cn \
--to=yangtiezhu@loongson.cn \
--cc=jpoimboe@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®