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From:   Zhouyi Zhou <zhouzhouyi@gmail.com>
Date:   Thu, 17 Mar 2022 23:22:28 +0800
Message-ID: <CAABZP2wZgZGAg5iVry21suEZ3e2PXhAhfwLvRCPvMRU5+zGG+g@mail.gmail.com>
Subject: Re: RCU: undefined reference to irq_work_queue
To:     Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc:     rcu <rcu@vger.kernel.org>, "Paul E. McKenney" <paulmck@kernel.org>,
        Josh Triplett <josh@joshtriplett.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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Hi,

On Thu, Mar 17, 2022 at 8:48 PM Hyeonggon Yoo <42.hyeyoo@gmail.com> wrote:
>
> Hello RCU folks,
>
> I like to use minimal configuration for kernel development.
> when building with tinyconfig + CONFIG_PREEMPT=y on arm64:
I invoke cross compiler to reproduce the bug on my X86 machine
$make  ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-
CC=aarch64-linux-gnu-gcc-10 tinyconfig
let CONFIG_PREEMPT=y  in .config
$make  ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-
CC=aarch64-linux-gnu-gcc-10 -j 16
LD      vmlinux
aarch64-linux-gnu-ld: kernel/rcu/update.o: in function `call_rcu_tasks':
update.c:(.text+0xb30): undefined reference to `irq_work_queue'
update.c:(.text+0xb30): relocation truncated to fit: R_AARCH64_CALL26
against undefined symbol `irq_work_queue'
>
> ld: kernel/rcu/update.o: in function `call_rcu_tasks':
> update.c:(.text+0xb2c): undefined reference to `irq_work_queue'
> update.c:(.text+0xb2c): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `irq_work_queue'
> make: *** [Makefile:1155: vmlinux] Error 1
>
> It seems RCU calls irq_work_queue() without checking if CONFIG_IRQ_WORK is enabled.
>
> --
> Thank you, You are awesome!
> Hyeonggon :-)
Meanwhile, there is no error for doing the same to build X86 kernel.
I think the reason is:
arch/x86/Kconfig select PERF_EVENT
and PERF_EVENT select IRQ_WORK

Hope my little research could provide some clues to solve the problem ;-)

You are welcome
Cheers
Zhouyi