[U-Boot] [PATCH v2] mpc86xx: set the DDR BATs after calculating true DDR size

[Timur Tabi]

Kumar Gala wrote:

>> We still have the problem that, on a 1.5GB system, U-Boot will think that there are 1.5GB of DDR, but the BAT will be set to 1GB.  When U-Boot tries to relocate itself, it will machine check.
>>
>> We need a way to tell U-Boot that we only have 1GB of DDR, but still have it tell Linux that we have 1.5GB of DDR.
> 
> is this situation you have today? (or just a concern?)

Just a concern.

Technically, we have the same problem on e500, except on e500 we use multiple TLBs to map the memory.  In theory, we need at most one TLB/BAT per DIMM slot, which means we would need four BATS on the MPC8641 HPCN.

Do we want to tell customers that U-Boot/Linux only supports power-of-two sizes of DDR?

-- 
Timur Tabi
Linux kernel developer at Freescale