[U-Boot-Users] Re: Usually dram test executed not on whole sdram

antonio.dibacco antonio.dibacco at aruba.it
Wed May 10 15:46:46 CEST 2006

Thank you for your help Wolfgang,

I disabled burst mode in ORx register of MPC880 and everything is fine.
The UPM table has to be double checked. 

Now I want to look for a dram test that exercise the burst mode. It could be
really useful in debugging these problems. 

Thank you very much,


Wolfgang Denk Scrive: 

> In message <200605092241.38323.antonio.dibacco at aruba.it> you wrote:
>> Anyone knows why in the u-boot normally the dram test is not executed on the 
>> whole DRAM? For example a lot boards that have 16MB specify start_address = 
>> 1MB and end_addr = 15MB. If the u-boot is executing in flash the DRAM can be 
>> written completely I think!
> The "mtest" can only be run after relocation to RAM, so you  have  to
> leave  out  the  memory  needed  ofr  exception vectors, U-Boot code,
> malloc arena, stack, etc. 
> For the POST tests no such restriction exists. 
> But you are on the wrong track. A memory test will  NOT  detect  your
> problem, as it is exercising pleain read / write accesses only, while
> your  problem  is most probably with burst mode accesses. Please read
> the FAQ! 
> 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
> Success in marriage is not so much finding the right person as it  is
> being the right person.

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