Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) What:		/sys/firmware/memmap/
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) Date:		June 2008
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) Contact:	Bernhard Walle <bernhard.walle@gmx.de>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) Description:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) 		On all platforms, the firmware provides a memory map which the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) 		kernel reads. The resources from that memory map are registered
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) 		in the kernel resource tree and exposed to userspace via
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) 		/proc/iomem (together with other resources).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) 		However, on most architectures that firmware-provided memory
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) 		map is modified afterwards by the kernel itself, either because
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) 		the kernel merges that memory map with other information or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) 		just because the user overwrites that memory map via command
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) 		line.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) 		kexec needs the raw firmware-provided memory map to setup the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) 		parameter segment of the kernel that should be booted with
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) 		kexec. Also, the raw memory map is useful for debugging. For
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) 		that reason, /sys/firmware/memmap is an interface that provides
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 		the raw memory map to userspace.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) 		The structure is as follows: Under /sys/firmware/memmap there
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 		are subdirectories with the number of the entry as their name::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 			/sys/firmware/memmap/0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 			/sys/firmware/memmap/1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 			/sys/firmware/memmap/2
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) 			/sys/firmware/memmap/3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 			...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) 		The maximum depends on the number of memory map entries provided
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 		by the firmware. The order is just the order that the firmware
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) 		provides.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 		Each directory contains three files:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) 		========  =====================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 		start	  The start address (as hexadecimal number with the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) 			  '0x' prefix).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 		end	  The end address, inclusive (regardless whether the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 			  firmware provides inclusive or exclusive ranges).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) 		type	  Type of the entry as string. See below for a list of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 			  valid types.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 		========  =====================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 		So, for example::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 			/sys/firmware/memmap/0/start
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 			/sys/firmware/memmap/0/end
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) 			/sys/firmware/memmap/0/type
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) 			/sys/firmware/memmap/1/start
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) 			...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) 		Currently following types exist:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) 		  - System RAM
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) 		  - ACPI Tables
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) 		  - ACPI Non-volatile Storage
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) 		  - reserved
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) 		Following shell snippet can be used to display that memory
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) 		map in a human-readable format::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) 		  #!/bin/bash
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) 		  cd /sys/firmware/memmap
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) 		  for dir in * ; do
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) 		      start=$(cat $dir/start)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) 		      end=$(cat $dir/end)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) 		      type=$(cat $dir/type)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) 		      printf "%016x-%016x (%s)\n" $start $[ $end +1] "$type"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) 		  done