Re: Build failure with v4.9-rc1 and GCC trunk -- compiler weirdness
From: Markus Trippelsdorf
Date: Wed Oct 19 2016 - 11:38:00 EST
On 2016.10.17 at 19:38 +0100, Will Deacon wrote:
> Hi all,
>
> I'm seeing an arm64 build failure with -rc1 and GCC trunk, although I
> believe that the new compiler behaviour at the heart of the problem
> has the potential to affect other architectures and other pieces of
> kernel code relying on dead-code elimination to remove deliberately
> undefined functions.
>
> The failure looks like:
>
> | drivers/built-in.o: In function `armada_3700_add_composite_clk':
> |
> | linux/drivers/clk/mvebu/armada-37xx-periph.c:351:
> | undefined reference to `____ilog2_NaN'
> |
> | linux/drivers/clk/mvebu/armada-37xx-periph.c:351:(.text+0xc72e0):
> | relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol
> | `____ilog2_NaN'
> |
> | make: *** [vmlinux] Error 1
>
This is a gcc bug, see:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72785
--
Markus