Re: 5.10 kernel series fails to build on newer toolchain: FAILED unresolved symbol filp_close

[Greg KH <gregkh@linuxfoundation.org>]

On Sun, Jun 08, 2025 at 08:27:35AM +0200, Philip Müller wrote:
> On 6/5/25 10:46, Greg KH wrote:
> > I have no context here, sorry...
> 
> So basically, starting with GCC 15.1 the kernel series doesn't compile again
> and errors out with: FAILED unresolved symbol filp_close. I tested now
> v5.10.237 as well, which failed similar to v5.10.238.
> 
> There are some Debian reports out there:
> 
> https://linux.debian.bugs.dist.narkive.com/2JKeaFga/bug-1104662-failed-unresolved-symbol-filp-close-linux-kernel-5-10-237
> https://www.mail-archive.com/debian-kernel@lists.debian.org/msg142397.html
> 
> And I also found this one:
> 
> https://lists-ec2.96boards.org/archives/list/linux-stable-mirror@lists.linaro.org/thread/7XFQI52N3KGUGFLPWCSJZW6DDFZCOXP4/
> 
> For GCC 14.1 I had to add the gnu 11 patch, which was discussed already.
> Also 5.4 and 5.15 still compile with the newer toolchain ...
> 
> -- 
> Best, Philip

> Commit b3bee1e7c3f2b1b77182302c7b2131c804175870 x86/boot: Compile boot code with -std=gnu11 too
> fixed a build failure when compiling with GCC 15. The same change is required for linux-5.10.236.
> 
> Signed-off-by: Chris Clayton <chris2553@googlemail.com>
> Modified-by: Philip Mueller <philm@manjaro.org>
> Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b3bee1e7c3f2b1b77182302c7b2131c804175870
> 
> 
> diff -rup linux-5.10.236.orig/arch/x86/Makefile linux-5.10.236/arch/x86/Makefile
> --- linux-5.10.236.orig/arch/x86/Makefile	2025-04-10 13:37:44.000000000 +0100
> +++ linux-5.10.236/arch/x86/Makefile	2025-04-26 19:37:38.294386968 +0100
> @@ -31,7 +31,7 @@ endif
>  CODE16GCC_CFLAGS := -m32 -Wa,$(srctree)/arch/x86/boot/code16gcc.h
>  M16_CFLAGS	 := $(call cc-option, -m16, $(CODE16GCC_CFLAGS))
>  
> -REALMODE_CFLAGS	:= $(M16_CFLAGS) -g -Os -DDISABLE_BRANCH_PROFILING -D__DISABLE_EXPORTS \
> +REALMODE_CFLAGS	:= -std=gnu11 $(M16_CFLAGS) -g -Os -DDISABLE_BRANCH_PROFILING -D__DISABLE_EXPORTS \
>  		   -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
>  		   -fno-strict-aliasing -fomit-frame-pointer -fno-pic \
>  		   -mno-mmx -mno-sse $(call cc-option,-fcf-protection=none)

Can you resend this in a format we can apply it in?

Also for the newer kernels, this was only backported to 6.6.y, so
anything older than that should need this, right?

thanks,

greg k-h