[U-Boot-Users] Application Performance optimization (MPC8260) with D cache enable

Om Vadlapatla pdfdoc15 at yahoo.com
Wed May 3 02:00:43 CEST 2006

I think I communicated my problem incorrectly. Since
this is an optical routing unit there is a lot of data
read write that occurs for running applications.

Although the data cache may not contribute
significantly to the performance of the boot process,
Mr Wei Zhou believes from his past experience that it
can help us increase our spead of operation of the
kernel, and the applications will run significantly
faster. I am new! 

My experience with this processor is limited! 

My resources are only the frescale documentation and
the manual. Any indication of other resources will
hugely help.

>The simplest way to use data cache the way you appear
>to want to use it is to use the BATs to map your I/O
>memory (minimum: >IMMR region) as  uncached and the
>rest of your used memory (flash + >RAM) as cached.  

Can any one please sugest an example with BAT mapping?
(or point to some resource - I don't mean feed me!).
I will try it out

>Ifyou don't do that, _everything_ is cached which is
a >Very Bad Thing[tm], 
>as you found out.

I am experimenting but I have a new shipment of
hardware on the way that has 4 channels which mean
more  data read writes which I believe means I will
need the d cache.

>I am not aware of anybody having success enabling 
>data cache without BATs/MMUs and successfully
>maintaining cache 
>coherency by hand (which is what you are hinting at).

Presently I am trying to figure the Registers I can
manipulate for:
 setting up memory
 Maitain cache coherency while running applications
I know HID0 helps with enabling & disabling locking
etc. of I&D caches but I want to figure out
configuring the MMU with the BAT registers.

Thank you,
Best regards,

Om Vadlapatla

PS:- Please excuse any no conforming netiquet as I
will learn very soon.

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