Re: [PATCH 2/3] m68k: Switch to asm-generic/barrier.h

Finn Thain
2014-02-06T07:05:09Z

On Wed, 5 Feb 2014, Geert Uytterhoeven wrote:

>
> #define barrier() __asm__ __volatile__("": : :"memory")
>
> I.e. it prevents gcc from:
> 1. Reordering instructions due to the volatile,
> 2. Caching data in registers due to the "memory".
>
> nop() still has the former, while the volatile casting in the I/O macros
> should have the same effect as the latter.

OK. Thanks for clarifying that for me.

>
> So yes, I think they can be removed. Can you test that, please?
>

Yes, but I don't know how long it will take. Removing the nop() instances
will affect the fb_setcolreg() routines for 3 types of nubus card and 4
types of on-board framebuffer so it means testing on a range of hardware.
Progress is slow because I can't access my Mac hardware except when I'm in
Melbourne.

Finn