[U-Boot] [Resend RFC PATCH 1/2] armv8: Fix dcache disable function

[york sun]

On 10/26/2016 12:47 PM, Stephen Warren wrote:
>
> There are two data structures in ARM U-Boot that describe memory layout:
>
> 1) A list of RAM memory regions. U-Boot uses these to know where to
> relocate itself to (it relocates itself to the top of RAM at boot), and
> to fill in the /memory node when booting an OS using DT (and other
> equivalent mechanisms when not using DT.)
>
> 2) For AArch64 specifically, there's a memory map table that defines all
> RAM and MMIO regions, and the translation table attributes required for
> those regions.
>
> Judging by your comments later in the original message, it sounds like
> it'd be fine to read from these structures during any dcache clean
> routine provided the table has already been cleaned. That makes using
> the tables much more tractable:-)
>

I think we need to benchmark walking through the MMU tables. It can map 
huge amount of memory. For our case, it is more than 16GB. I have been 
reluctant to do so for the size. I am now back testing to revert _this_ 
patch, hoping to confirm what I learned from this discussion. After 
that, I will see how long it takes to flush all cached addresses by VA.

York