This is due to the way the P5020 (and possibly the P5040 I don't know) map memory.caseycullen wrote:Also, does this correspond to the physical memory in the system? Can it be edited to reflect the actual physical memory present?xeno74 wrote:Please try it with mem=3500M.
They map all the ram in a single block starting a 0x00000000 and anding at <RAM-SIZE> If you have more than 3568 M of Ram you will have RAM with physical addresses of 0xdf000000 - 0xffffffff
These addresses are reserved for registers and inbound windows in the PCI-e controllers, and therefore cannot be DMA'd to. The kernel will incorrectly allocate ring-buffers in this range if you don't limit the amount of RAM reported. There is a possible fix in the pipeline, but it looks like it either doesn't work or hasn't made it to mainline yet.
We are aware of the problem, and so are NXP, it is being worked on.
For now stick with MEM=3500M