24 Apr
2008
24 Apr
'08
3:07 p.m.
On Thursday 24 April 2008, Josh Boyer wrote:
Hard to define "works fine" - this is the same 440EPx platform I'm asking about over in the embedded Linux mailing list. I'm pretty sure the kernel doesn't flag SDRAM as Guarded,
Yes, and the 4xx code to dynamically set the SDRAM TLB's in the SPD code doesn't set it either. So it really isn't needed.
Actually, that's not true for kernel memory. We pin 256MiB TLBs to cover lowmem in AS0, and the Guarded bit is set. We set it to prevent speculative access to memory holes where the 256MiB TLB covers more address space than there is physical DRAM.
I wasn't aware of this. Thanks for the explanation.
Best regards, Stefan