Debian-Pi-Aarch64/docs/notes/pi4_cpu_stepping.md

786 B

BCM2711 SoC Version about stepping

2711ZPKFSB06B0T & 2711ZPKFSB06C0T

The stepping "C0T" is newer than "B0T".

Run the command to check:

od -An -tx1 /proc/device-tree/emmc2bus/dma-ranges

It will show different output depending on the stepping:

B0

pi@raspberrypi:~$ od -An -tx1 /proc/device-tree/emmc2bus/dma-ranges
 00 00 00 00 c0 00 00 00 00 00 00 00 00 00 00 00
 40 00 00 00

C0

pi@raspberrypi:~$ od -An -tx1 /proc/device-tree/emmc2bus/dma-ranges
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 fc 00 00 00

In the case of the BCM2711, it looks like the two main fixes are related to RAM addressing:

  • 1.The EMMC2 bus can only directly address the first 1GB.
  • 2.The PCIe interface can only directly address the first 3GB.