1、前言

(1)本文是基于hi3516dv300芯片的ubootExplain with the kernel;
(2)dv300The chip is actually connected to the board2G内存,dv300The actual maximum chip only supports2G内存;

2、hi3516dv300The memory address range of the chip

(1)By consulting the data sheet《Hi3516DV300 专业型 Smart IP Camera SoC 用户指南》,dv300The memory address range of the chip is0x8000_0000-0xFFFF_FFFF,最大能支持2G内存;
(2)HiSilicon chips divide memory intommz内存和os内存,最终linuxThe memory that the system can manage is less than the actual memory size,Because part of the memory needs to be allocated asmmz;

3、Memory management of HiSilicon chips

(1)in the HiSilicon chip,将内存划分为OS内存和MMZ内存,板子上的2Gpart of memoryOS内存,一部分做MMZ内存;
(2)OS内存：就是分配给linux内核管理的内存,Allocated for use by the kernel and applications;
(3)MMZ(Media Memory Zone,multimedia memory area)：Unique to HiSilicon,Because the HiSilicon chip is a chip specially used for audio and video encoding and decoding,requires a lot of memory,In order to the speed of the codec,The bottom layer of the HiSilicon driver will manage a part of the memory,Specially used for audio and video codec;
总结：Divide the actual physical memory into two parts——OS内存和MMZ内存,Two parts of memory management is independent of each other;

4、分配OS内存和MMZprinciples of memory

(1)分配的OS内存和MMZThe total size of the combined memory cannot exceed the size of the actual physical memory;
(2)OS内存和MMZThe memory addresses of the memory cannot overlap with each other,Otherwise there will be a memory stampede;
(3)The total physical memory size remains unchanged,OS内存和MMZAllocation between memory is trade-off,The share allocated between the two needs to be balanced,以达到最优性能;

5、设置MMZ内存

5.1、加载hi_osal.ko驱动

mmz_buf0_start=0xD8000000;
mmz_buf0_size=60M;
mmz_start=0xDBC00000;		# mmz start addr
mmz_size=579M;			# 579M, mmz size

insmod hi_osal.ko anony=1 mmz_allocator=hisi mmz=anonymous,0,$mmz_start,$mmz_size:buf0,0,$mmz_buf0_start,$mmz_buf0_size || report_error

(1)在海思提供的SDKThere will be a script to load the driver in the package,比如dv300The loading script for the chip isload3516dv300,The above is the loading of the excerpthi_osal.ko的脚本;
(2)加载hi_osal.ko时传入MMZThe start address and size of memory,The driver supports incoming multiple blocksMMZ内存地址;

5.2、查看MMZ内存：/proc/media-mem

~ # cat /proc/media-mem 
+---ZONE: PHYS(0xD8000000, 0xDBBFFFFF), GFP=0, nBYTES=61440KB,    NAME="buf0"
+---ZONE: PHYS(0xDBC00000, 0xFFEFFFFF), GFP=0, nBYTES=592896KB,    NAME="anonymous"
   |-MMB: phys(0xDBC00000, 0xDBC07FFF), kvirt=0xF0DE8000, flags=0x00000001, length=32KB,    name="sys_scale_coef"
   |-MMB: phys(0xDBC08000, 0xDBC27FFF), kvirt=0x00000000, flags=0x00000000, length=128KB,    name="TDE_MEMPOOL_MMB"
   |-MMB: phys(0xDBC28000, 0xDBC43FFF), kvirt=0xF0FE0000, flags=0x00000001, length=112KB,    name="gdc_node_buf"
   |-MMB: phys(0xDBC44000, 0xDBC44FFF), kvirt=0xF0C95000, flags=0x00000001, length=4KB,    name="GDC int_pole_co"
   |-MMB: phys(0xDBC45000, 0xDBCBFFFF), kvirt=0xF1100000, flags=0x00000001, length=492KB,    name="VGS_NodeBuf"
   |-MMB: phys(0xDBCC0000, 0xDBCC0FFF), kvirt=0xF0CD9000, flags=0x00000001, length=4KB,    name="dis_node_buf"
   |-MMB: phys(0xDBCC1000, 0xDC0C0FFF), kvirt=0x00000000, flags=0x00000000, length=4096KB,    name="hifb_layer0"
   |-MMB: phys(0xDC0C1000, 0xDC0D0FFF), kvirt=0xF14D0000, flags=0x00000001, length=64KB,    name="HIFB COEF"
   |-MMB: phys(0xDC0D1000, 0xDC105FFF), kvirt=0xF1C80000, flags=0x00000001, length=212KB,    name="IVE_QUEUE"
   |-MMB: phys(0xDC106000, 0xDC106FFF), kvirt=0xF0EDD000, flags=0x00000003, length=4KB,    name="IVE_TEMP_NODE"
   |-MMB: phys(0xDC107000, 0xDC116FFF), kvirt=0xF1CE0000, flags=0x00000001, length=64KB,    name="SVP_NNIE_QUEUE"
   |-MMB: phys(0xDC117000, 0xDC11AFFF), kvirt=0xF12F8000, flags=0x00000003, length=16KB,    name="SVP_NNIE_MODLE_"

---MMZ_USE_INFO:
 total size=654336KB(639MB),used=5228KB(5MB + 108KB),remain=649108KB(633MB + 916KB),zone_number=2,block_number=12

(1)从上面可知,MMZThere are two pieces of memory：名字是buf0,大小是61440KB;名字是anonymous,大小是592896KB;
(2)Just loading with ushi_osal.ko时指定的MMZMemory parameters match;

6、设置OS内存

6.1、设置bootargs

~ # cat /proc/cmdline 
mem=1408M console=ttyS0,115200 root=/dev/mmcblk0p7 rootfstype=squashfs rootwait

(1)从bootargs中可以得知,OS内存分配了1408M,The starting address is not specified here,Analysis of the kernel source code,The memory start address is0x80000000;
(2)具体bootargsHow the memory specified in takes effect,参考博客：《linux内存管理——内存大小、Analysis and modification of the starting address》;

6.2、查看OS内存：free

~ # free
             total         used         free       shared      buffers
Mem:       1419980       132636      1287344          448        23808
-/+ buffers:             108828      1311152
Swap:            0            0            0

7、Memory management figure

-----|----------------|  0x80000000   # Memory managed by OS. 
1408M|                |                                                 
	 |      OS        |                                                 
-----|----------------|  0xD8000000   #Memory managed by MMZ block buf0. 
60M  |                |                                                 
	 |    MMZ：buf0   |                                                 
-----|----------------|  0xDBC00000   # Memory managed by MMZ block anonymous. 
579M | MMZ:anonymous  |
	 |                |  
-----|----------------|  0xFFF00000   # End of memory managed by MMZ.