Re: [linux-stable-rc:linux-3.16.y 2872/3488] head64.c:undefined reference to `__gcov_exit'

[Arnd Bergmann <arnd@arndb.de>]

On Fri, Feb 16, 2018 at 7:21 PM, kbuild test robot
<fengguang.wu@intel.com> wrote:
> Hi Andrey,
>
> It's probably a bug fix that unveils the link errors.
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-3.16.y
> head:   0b9f4cdd4d75131d8886b919bbf6e0c98906d36e
> commit: 3cb0dc19883f0c69225311d4f76aa8128d3681a4 [2872/3488] module: fix types of device tables aliases
> config: x86_64-allmodconfig (attached as .config)
> compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
> reproduce:
>         git checkout 3cb0dc19883f0c69225311d4f76aa8128d3681a4
>         # save the attached .config to linux build tree
>         make ARCH=x86_64
>
> All errors (new ones prefixed by >>):
>
>    arch/x86/kernel/head64.o: In function `_GLOBAL__sub_D_00100_1_early_pmd_flags':
>>> head64.c:(.text.exit+0x5): undefined reference to `__gcov_exit'
>    arch/x86/kernel/head.o: In function `_GLOBAL__sub_D_00100_1_reserve_ebda_region':
>    head.c:(.text.exit+0x5): undefined reference to `__gcov_exit'
>    init/built-in.o: In function `_GLOBAL__sub_D_00100_1___ksymtab_system_state':
>    main.c:(.text.exit+0x5): undefined reference to `__gcov_exit'
>    init/built-in.o: In function `_GLOBAL__sub_D_00100_1_root_mountflags':
>    do_mounts.c:(.text.exit+0x10): undefined reference to `__gcov_exit'
>    init/built-in.o: In function `_GLOBAL__sub_D_00100_1_initrd_load':
>    do_mounts_initrd.c:(.text.exit+0x1b): undefined reference to `__gcov_exit'
>    init/built-in.o:initramfs.c:(.text.exit+0x26): more undefined references to `__gcov_exit' follow

I think this is a result of using a too new compiler with the old 3.16
kernel. In order
to build with gcc-7.3, you need to backport

05384213436a ("gcov: support GCC 7.1")

It's already part of stable-3.18 and later, but not 3.2 and 3.16.

      Arnd

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