How to emulate Persistent Memory

1. 下载内核代码包

到官网https://www.kernel.org/，下载内核代码包，需要4.2以上的版本

2. 解压编译内核

tar -xvf linuxxxx.tar.xz

yum install ncurses-devel ncurses

yum install openssl-devel

make -jx

编译之前需要根据PMDK的官网的指示，首先通过make nconfig设置几个参数

分别是

Device Drivers ---> 
        {*} NVDIMM (Non-Volatile Memory Device) Support --->
            <M>   PMEM: Persistent memory block device support
            <M>   BLK: Block data window (aperture) device

Processor type and features --->
        [*] Support non-standard NVDIMMs and ADR protected memory
        [*] Device memory (pmem, etc...) hotplug support
    File systems --->
        [*] Direct Access (DAX) support 

nconfig依赖于curses包，所以需要安装curses

然后就可以开始编译内核

3. 安装内核

yum install elfutils-libelf-devel

make install_modules install

这里需要安装一个libelf包

4. 设置pmem的内存保留区间并通过grub生成配置，重启即可

1. 修改grub文件中GRUB_CMDLINE_LINUX="memmap=nn[KMG]!ss[KMG]"

2. sudo grub2-mkconfig -o /boot/grub2/grub.cfg

3. 重启之后，fdisk -l就会显示pmem设备

image

通过dmesg也可以看到系统内存地址空间中有一段成为了Persistent

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