[U-Boot] [RFC] command/cache: Add flush_cache command

Sricharan R
2013-03-21T05:02:23Z

On Thursday 21 March 2013 06:01 AM, Scott Wood wrote:
> On 03/20/2013 07:27:29 PM, Michael Cashwell wrote:
>> On Mar 20, 2013, at 7:48 PM, Scott Wood <scottwood@freescale.com> wrote:
>>
>> > On 03/20/2013 06:33:41 PM, Michael Cashwell wrote:
>> >
>> >> What is the purpose of limiting the memory range to be flushed? Is there a reason one might want to NOT flush certain data sitting in a dirty cache line out to memory before doing a go or boot command?
>> >
>> > Because it would take a while to flush all of RAM?
>>
>> "Flushing all of RAM" is what trips me up. Fundamentally, that puts the cart in front of the horse. The goal isn't to flush all of RAM but rather to flush all of cache.
>
> Right, I was just responding to your question of, "What is the purpose of limiting the memory range to be flushed?"
>
>> Iterating over the small thing rather than the large would seem reasonably efficient.
>>
>> But as you say, if there are architectures where that can't be done and you must pass GBs of physical address space (rather than KB of cache space) through some process then range limiting it does make sense.
>
> Right. The range specified is a minimum to be flushed -- if a particular architecture finds it easier/quicker to flush everything instead, that's fine.
>
So in your case, how do you find out the addresses of buffers to be flushed from command ?
Just thinking how this can be used generically ?

Regards,
Sricharan