Re: [PATCH v4 1/5] getcpu_cache system call: cache CPU number of running thread

[Geert Uytterhoeven]

Hi Linus,

On Sat, Feb 27, 2016 at 7:35 PM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Sat, Feb 27, 2016 at 6:58 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>>
>> Paul's patches have the following structure:
>>
>> struct thread_local_abi {
>>         union {
>>                 struct {
>>                         u32     cpu_id;
>>                         u32     seq;
>>                 };
>>                 u64 cpu_seq;
>>         };
>>         unsigned long post_commit_ip;
>> };
>
> Please don't do "unsigned long" in ABI structures any more.
>
> Make it u64, and make sure it is 64-bit aligned (which it would be in
> this case). Make it so that we don't have to have separate compat
> paths.

__alignof__(u64) is not 8 on all architectures.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds