Stefan Roese wrote:
On Thursday 27 March 2008, Larry Johnson wrote:
Yes, we normally use ECC modules in our testing. I've been looking at a patch for "initdram()" Denali SPD, but I've been waiting to see how your "CFG_MEM_TOP_HIDE" patch would turn out.
As things stand now, can I assume that boards using the Denali SPD will also define "CFG_MEM_TOP_HIDE", and therefore initdram() should continue to return the full size of the memory?
Correct.
The only place that the last 256 bytes of memory are touched is when "dflush()" is called to zero the SDRAM.
To be more specific, in the dcbz_area() call.
This does not cause a Machine Check interrupt. I am guessing that all the writes from "dflush()" are aligned, and therefore there are no burst that access beyond the end of of the SDRAM memory space. If so, then my inclination is not to change this part of the code. Does this make sense?
I recommend to change it this way:
/* Zero the memory */ debug("Zeroing SDRAM...");
dcbz_area(CFG_SDRAM_BASE, dram_size);
dcbz_area(CFG_SDRAM_BASE, dram_size - CFG_MEM_TOP_HIDE); dflush();And perhaps put something like:
#ifndef CFG_MEM_TOP_HIDE #error "Please define CFG_MEM_TOP_HIDE (see README) in your board config file!" #endif
at the top of the file. What do you think?
Best regards, Stefan
That sound fine, I'll try to get a patch out soon.
Best regards, Larry