[U-Boot-Users] Re: "go addr" Question...

Wolfgang Denk wd at denx.de
Tue Sep 6 21:43:24 CEST 2005

In message <431DD0C1.6040707 at smiths-aerospace.com> you wrote:
> U-boot typically runs with instruction cache enabled and data cache 
> disabled (experience base: PowerPC).  This is because instruction cache 

We typically enable icache, that's true. If data cache is on  or  off
depends, even on PowerPC. See the README.

> "just works" and is very beneficial and data cache generally causes 
> massive grief (it is pretty much useless without setting up the BATs or 
> full MMU on the PowerPC).

Data cache can be very important if you need an initial stack  before
you have any writable memory on the system.

> It sounds like Robin has data caching turned on, which would explain why 
> he needs to flush the data cache before jumping to his newly loaded 

No, it does not. As I just explained, all download commands implement
cache flushing (I think).

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
It took him several minutes to understand any new idea  put  to  him,
and  this is a very valuable trait in a leader, because anything any-
one is still trying to explain to you after two minutes  is  probably
important  and anything they give up after a mere minute or so is al-
most certainly something they shouldn't have been bothering you  with
in the first place.                   - Terry Pratchett, _Reaper Man_

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