[U-Boot-Users] fishing for ideas

[VanBaren, Gerald (AGRE)]

> -----Original Message-----
> From: u-boot-users-admin at lists.sourceforge.net
> [mailto:u-boot-users-admin at lists.sourceforge.net]On Behalf Of Benjamin
> Collar
> Sent: Friday, October 01, 2004 12:04 PM
> To: u-boot-users at lists.sourceforge.net
> Subject: [U-Boot-Users] fishing for ideas
>
>
> Greetings folks
>
> Yesterday's problems have been overcome. Mostly I was just
> misunderstanding what was going on / what was supposed to be going on.
> Thanks for the clues overall.
>
> But there is a bit more to it. At the end of the day yesterday, I
> performed exactly the same 'loads' command,  with exactly the
> same srec
> file, as I had done at the beginning of the day, and it worked. Talk
> about frustration!
>
> Today I was working on it and loaded a linux kernel image. When I
> 'loads' it, using the u-boot command line, into ram, the 'md'
> command at
> the loaded area shows
>
> 00010000: 27051956 d3232bea 415d1e66 0005ba2c    '..V.#+.A].f...,
> 00010010: 7d8c5a14 3940ffff 914c0000 3bffffe0    }.Z.9 at ...L..;...
> 00010020: 4c696e75 782d322e 342e3138 00000000    Linux-2.4.18....
> 00010030: 00000000 00000000 00000000 00000000    ................
>
> while objdump shows
>
>  00000 27051956 d3232bea 415d1e66 0005ba2c  '..V.#+.A].f...,
>  00010 00000000 00000000 82847f95 05070201  ................
>  00020 4c696e75 782d322e 342e3138 00000000  Linux-2.4.18....
>
> of course, you'll notice immediately that the 5th word is completely
> bogus, among others.
>
> I've spoken with the board developer (who also wrote a bootloader for
> the board) and showed him the sdram initialization function,
> and he said
> it was correct. However, I've got the behavior shown above. Is there
> another reason why this sort of corruption would happen? (btw, using
> 'cu' to download the image into RAM).
>
> Thanks for any tips
> Ben
>
> --
> Benjamin Collar
> Siemens AG
> CT SE 2
> Embedded Linux
> 089-636-53711

Just because he said his bootloader works doesn't necessarily mean it really and truly works (I'm a skeptic: my first statement is invariably "show me").

Do you have caching enabled?  Did he?  Caching enables burst mode which is a well know cause of SDRAM corruption due to what appears to be and is claimed to be working initialization but actually is not correct.

Can you create a situation where the same operation works on his bootloader but doesn't work on yours?  Can you make his bootloader fail like yours when doing the same or similar operation (not necessarily downloading with cu)?

Yours with no answers, just questions...
gvb

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