[U-Boot-Users] uboot newbie - tqm823 and memory conf question

[Thomas Maenner <tmaenner@aehr.com>]

OK, thanks again!

Wolfgang Denk wrote:
> In message <Pine.LNX.4.44.0302171146460.7989-100000@loki.aehr.com> you wrote:
> 
>>Thanks!
> 
> 
> You're welcome.
> 
> 
>>>So depending if you have CAN on your modules or  not  you  can  chose
>>>form CS4...CS7 or from CS3...CS7.
>>>
>>
>>Well then, how does the CPU "know" about that area?
> 
> 
> Ummm... please read the  memory  controller  section  of  the  MPC8xx
> User's Manual.

Found it! Chapter 15. Digesting it...

---snip---
> 
>>- How does the CPU know, that it is SRAM or something else?
> 
> 
> It doesn't know, and it doesn't need to know. It  just  goes  through
> the  memory  controller registers to find a BRx/ORx pair that matches
> the physical address, and  then  it  accesses  the  corresponding  CS
> according to the other params in BRx/ORx.
> 
> Not that the scanning always starts at  BR0/OR0,  so  if  you  define
> overlapping memory regions always the first one will win.
> 

Good info.

---snip---
> 
>>I will search in the source there.
> 
> 
> What for? Just add it to your Linux device driver's init() code.
> 

If the "when" almost doesn't matter, it could be done there.

---snip---

Thanks a lot Wolfgang for your help!

Have a successful show in Nuremberg!

-- 
Thomas Maenner