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

[Scott Wood <scottwood@freescale.com>]

On 03/21/2013 12:02:23 AM, Sricharan R wrote:
> 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 ?

I'm not sure what you're asking.  How does the user know what address  
range to pass to the command?  It's whatever covers the program they  
want to run.

-Scott