On Thu, Mar 17, 2022 at 11:22:28PM +0800, Zhouyi Zhou wrote: > Hi, > > On Thu, Mar 17, 2022 at 8:48 PM Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx> 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' Right. that was exactly what I faced :) > > > > 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 Right. selecting anything that selects IRQ_WORK solves the problem. Simply enabling printk also solves this. > Hope my little research could provide some clues to solve the problem ;-) Thank you for kind reply! BTW, can we just fix this? (e.g. by conditionally compiling the problematic code or always selecting IRQ_WORK) > You are welcome > Cheers > Zhouyi -- Thank you, You are awesome! Hyeonggon :-)
