[U-Boot] mpc85xx debug TLB entry

[Prabhakar Kushwaha]

On 10/11/2012 05:51 AM, Scott Wood wrote:
> I'm debugging some SPL changes and am still having a hard time 
> following the initial TLB flow.  We seem to be creating an entry in 
> AS0 -- how is that not conflicting with the TLB entry we're running from? 

The behaviour of overlapping TLB entries is undefined for e500v2 processor.
Luckily it is working for P1010RDB, P1020RDB, P2020RDB-PC and BSC9131RDB.

> Why is the debug TLB 256K?  Why is it not aligned to 256K? 

Temp TLB  is created because label "nexti"  resize  the current TLB to 
4K. So create one for debugging with CONFIG_SYS_MONITOR_BASE.
Although we are creating TLB entry for 0x11001000 but actual TLB entry 
is created with 0x11000000,256K aligned. Same is verified from debugger.

> How do you know that MAS2_I is correct (it should be cacheable in the 
> loaded-by-spl case)?

I set it as MAS2_I because same is done while creating AS1 TLB entries 
for CONFIG_SYS_MONITOR_BASE during CONFIG_SYS_RAMBOOT.

>
> I'm trying to get the p2020rdb-pca SPL payload to run out of L2 SRAM, 
> and I see weird TLB behavior causing a hang if I don't comment out the 
> debug TLB.
>
>
is the root cause MAS2_I or 256K TLB entries created?

The proper solution would be to create temp Debug TLB for 
CONFIG_SYS_RAMBOOT after resizing current TLB to 4K.
Please suggest.

Regards,
Prabhakar