Re: [tip:smp/hotplug 4/8] kernel/cpu.c:1252:3: error: unknown field 'startup' specified in initializer

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 2016-09-02 17:42:33 [+0800], kbuild test robot wrote:
> compiler: or32-linux-gcc (GCC) 4.5.1-or32-1.0rc1
> 
> >> kernel/cpu.c:1252:3: error: unknown field 'startup' specified in initializer
> >> kernel/cpu.c:1252:3: warning: missing braces around initializer
>    kernel/cpu.c:1252:3: warning: (near initialization for 'cpuhp_bp_states[0].<anonymous>')
> >> kernel/cpu.c:1253:3: error: unknown field 'teardown' specified in initializer
>    kernel/cpu.c:1425:3: error: unknown field 'startup' specified in initializer
>    kernel/cpu.c:1425:3: warning: missing braces around initializer
>    kernel/cpu.c:1425:3: warning: (near initialization for 'cpuhp_ap_states[121].<anonymous>')
>    kernel/cpu.c:1426:3: error: unknown field 'teardown' specified in initializer

This is a compiler issue. We have:
| struct cpuhp_step {
|         const char              *name;
|         union {
|                 int             (*startup)(unsigned int cpu);
|                 int             (*startup_multi)(unsigned int cpu,
|                                                  void *node);
|         };
…
| };
This unnamed union fields are valid as of ISO C11.
It seems that gcc 4.5 and earlier can't access ->startup. According to
[0] this is supported since gcc 4.6.

[0] https://gcc.gnu.org/wiki/C11Status

Sebastian