January 8, 2021

EBAZ4205 Bitcoin miner board - Ram

You would think there would be little or nothing to say.

We have 256M of ram, be where the heck is it in the address map? The 4G address space sets aside the first 1G for ram, so that narrows it down somewhat. It turns out that by the time U-boot is running, the same 256G is aliased to four locations:

0x0000_0000 to 0x0fff_ffff
0x1000_0000 to 0x1fff_ffff
0x2000_0000 to 0x2fff_ffff
0x3000_0000 to 0x3fff_ffff
That is simple enough. Take your pick.

There is also 256K of OCM (on chip memory). The above is the DDR ram. By the time U-Boot is running and willing to talk to us, the OCM is at the high end of the address map at:

0xfffc_0000 to 0xffff_ffff
That is all I know at this time.
Feedback? Questions? Drop me a line!

Tom's Computer Info / [email protected]