Why is the RAM physically unaccessible beyond 640 KByte at this stage?
Which chipset / board? It's not necessarily unaccessible.
AMD Geode LX/CS5536
You have to be careful to not check the range from 640kb to 1MB, after that it should be ok again.
E.g. try this if you have 64MB or RAM:
ram_check(0, 640 * 1024); ram_check(1024 * 1024, 64 * 1024 * 1024);
I see.
If this does not work, then you likely have a RAM setup problem. The fact that the 640kb-1mb range doesn't work with ram_check() is sort of expected.
Ok.
Is it a specific (legacy) memory controller mode?
The northbridge / RAM controller has some registers which allow you to control what happens with the accesses from 640KB to 1MB, I think it depends on that config...
I'll have a look at datasheet.
Thank you very much, llandre
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