Qemu 文件系統支持swap ubuntu16.04

1.在ubuntu 製作一個64M的amge

$dd if=/dev/zero of=swap.img bs=512 count=131072

2.通過mtd卡方式加載swap.img 到qemu

qemu-system-aarch64 -machine virt -cpu cortex-a57 -machine type=virt -nographic -m 2048 -smp 2 -kernel arch/arm64/boot/Image --append "rdinit=/linuxrc console=ttyAMA0"

swapoff      swapon       switch_root
/ # mkswap /dev/mtdblock0 
Setting up swapspace version 1, size = 134213632 bytes
random: mkswap urandom read with 17 bits of entropy available
UUID=04eaf296-2598-4058-bf9f-2c7a364a8218
/ # swapo
swapoff  swapon
/ # swapon /dev/mtdblock0 
Adding 131068k swap on /dev/mtdblock0.  Priority:-1 extents:1 across:131068k SS
/ # free on
             total       used       free     shared    buffers     cached
Mem:       1988072      10828    1977244       1888          4       1888
-/+ buffers/cache:       8936    1979136
Swap:       131068          0     131068
/ # 

3.這個主要用到內部mtd設備作爲swap。

4.SD

qemu-system-arm -M vexpress-a9 -smp 4 -m 1024M -kernel arch/arm/boot/zImage --append "rdinit=/linuxrc console=ttyAMA0 loglevel=8" -dtb arch/arm/boot/dts/vexpress-v2p-ca9.dtb -nographic -sd swap.img

/ # 
/ # 
/ # ls /dev/mmcblk0 
/dev/mmcblk0
/ # 
/ # 
/ # 
/ # mkswap /dev/mmcblk0 
Setting up swapspace version 1, size = 67104768 bytes
UUID=ebbbc1e4-1e36-4aaf-b86a-dcea99324124
/ # swapon /dev/mmcblk0 
Adding 65532k swap on /dev/mmcblk0.  Priority:-1 extents:1 across:65532k SS
/ # free -m
             total       used       free     shared    buffers     cached
Mem:          1006         15        990          1          0          1
-/+ buffers/cache:         13        992
Swap:           63          0         63
/ #