The '256 KiB / driver only models 256 KiB of main RAM' note was from an early
dump and is wrong. The driver maps 0x00000000-0x01ffffff, which on this
bit-addressed space is 0x2000000 units = 0x400000 bytes = 4 MiB, confirmed
empirically (mainram share size == 4194304). Keep the correction with the
original so the stale figure cannot mislead again.
SDD
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