[U-Boot] ppc: using d-cache for C stack and as cache at the same time?

Wolfgang Denk
2009-04-01T09:14:36Z

Dear Jens Gehrlein,

In message <49D323E5.9080100@tqs.de> you wrote:
>
> AFAIK, while running from flash, u-boot uses (part of) d-cache on some
> platforms for the C stack. I think, it's on MPC83xx and MPC85xx?
>
> Does anybody know, if I can use the remaining part of the d-cache
> as normal d-cache, e.g. to generate bursts on the SDRAM interface
> while testing the RAM?

On which platform?

Note that implementing a memory test that actually triggers burst
mode accesses is really, really tricky. You probably do NOT want to
do this while running from flash (i. e. from a very restrictive
envrionment). You might want to have a look at examples/test_burst*
but note that this code was written for a MPC8xx system, so changes
will be required for 83xx or 85xx.

Also note that a much more reliable test for burst mode errors is to
boot Linux with root file system over NFS and then compile the Linux
kernel on the target.

Best regards,

Wolfgang Denk

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Bus error -- driver executed.