Query about: ARM11 MPCore: preemption/task migration cache coherency

[Catalin Marinas]

On 31 May 2012 11:38, bill4carson <bill4carson at gmail.com> wrote:
> On 2012年05月31日 11:19, Catalin Marinas wrote:
>> BTW, see this as a starting point (and a hack):
>>
>> http://article.gmane.org/gmane.linux.ports.arm.kernel/51556
>
> I think we has some mis-understanding here :(
>
> As for:v6_flush_kern_dcache_area/v6_flush_kern_dcache_all
> these two hooks is supposed to be globally effective, *not*
> locally!
>
> Hence, there should below fix to make it as globally effective.
>
>
> +#ifdef CONFIG_SMP
> +       ldr     r2, [r0]                        @ read for ownership
> +       str     r2, [r0]                        @ write for ownership
> +#endif /* CONFIG_SMP */
>
> Or there maybe some other better solution for this issue.

I still didn't fully understand what the problem is. So, to make sure,
if you run some applications from flash using a yaffs filesystem, you
get random crashes. Is this correct? If yes, a solution is to actually
call flush_dcache_page() on the CPU that does the page copying from
flash into RAM, which could be the yaffs filesystem.

-- 
Catalin