Re: [tip:x86/asm 3/3] lib/bug.c:135: undefined reference to `__start___bug_table'

[Peter Zijlstra <peterz@infradead.org>]

On Thu, Mar 30, 2017 at 05:49:27PM +0200, Peter Zijlstra wrote:
> On Thu, Mar 30, 2017 at 09:02:31PM +0800, kbuild test robot wrote:
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/asm
> > head:   19d436268dde95389c616bb3819da73f0a8b28a8
> > commit: 19d436268dde95389c616bb3819da73f0a8b28a8 [3/3] debug: Add _ONCE() logic to report_bug()
> > config: arm-efm32_defconfig (attached as .config)
> > compiler: arm-linux-gnueabi-gcc (Debian 6.1.1-9) 6.1.1 20160705
> > reproduce:
> >         wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> >         chmod +x ~/bin/make.cross
> >         git checkout 19d436268dde95389c616bb3819da73f0a8b28a8
> >         # save the attached .config to linux build tree
> >         make.cross ARCH=arm 
> > 
> > All errors (new ones prefixed by >>):
> > 
> >    lib/lib.a(bug.o): In function `find_bug':
> > >> lib/bug.c:135: undefined reference to `__start___bug_table'
> > >> lib/bug.c:135: undefined reference to `__stop___bug_table'
> 
> Blergh.. this cures it for me.
> 
> Ideally all those would use RW_DATA_SECTION, but alas.
> 

> diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
> index c74ae9c..c8a3b61 100644
> --- a/arch/x86/kernel/vmlinux.lds.S
> +++ b/arch/x86/kernel/vmlinux.lds.S
> @@ -146,6 +146,7 @@ SECTIONS
>  		_edata = .;
>  	} :data
>  
> +	BUG_TABLE
>  
>  	. = ALIGN(PAGE_SIZE);
>  	__vvar_page = .;

Also, I have absolutely 0 clues as to why x86 builds without this :/