Re: [Question] Alignment requirement for readX() and writeX()

[Arnd Bergmann]

On Fri, Jul 30, 2021 at 7:31 PM Boqun Feng <boqun.feng@xxxxxxxxx> wrote:
> On Fri, Jul 30, 2021 at 06:58:30PM +0200, Arnd Bergmann wrote:
>
> If we want to check, I'd expect we do the checks inside
> readX()/writeX(), for example, readl() could be implemented as:
>
>         #define readl(c)                                        \
>         ({                                                      \
>                 u32 __v;                                        \
>                                                                 \
>                 /* alignment checking */                        \
>                 BUG_ON(c & (sizeof(__v) - 1));                  \
>                 __v = readl_relaxed(c);                         \
>                 __iormb(__v);                                   \
>                 __v;                                            \
>         })
>
> It's a runtime check, so if anyone hates it I can understand ;-)

Right, I really don't think that adds any value, this just replaces one
oops message with a more different oops message, while adding
some overhead.

        Arnd