查看centos版本
cat /etc/redhat-release
#-> CentOS Linux release 7.4.1708 (Core)
查看自己內核版本
uname -r #-> 3.10.0-693.el7.x86_64
開始安裝編譯模塊
yum install kernel-devel kernel-headers
cd /tmp
wget http://vault.centos.org/7.4.1708/os/Source/SPackages/kernel-3.10.0-693.el7.src.rpm
rpm -ihv kernel-3.10.0-693.el7.src.rpm (這時會在/root/rpmbuild/SOURCES下生成tar.xz包)
cd ~/rpmbuild/SOURCES
tar Jxvf linux-3.10.0-693.el7.tar.xz -C/usr/src/kernels/
cd /usr/src/kernels/
mv $(uname -r) $(uname -r)-old
mv linux-3.10.0-693.el7 $(uname -r)
cd $(uname -r)
make mrproper
cp ../$(uname -r)-old/Module.symvers ./
cp /boot/config-$(uname -r) ./.config
make oldconfig
make prepare
make scripts
make CONFIG_BLK_DEV_NBD=m M=drivers/block
cp drivers/block/nbd.ko /lib/modules/$(uname -r)/kernel/drivers/block/
depmod -a
最後，modprobe nbd 啓用nbd模塊
期間會遇到錯誤，問題及解決辦法如下：
1. make scripts
錯誤：
Makefile:901: "Cannot use CONFIG_STACK_VALIDATION, please install libelf-dev or elfutils-libelf-devel"
解決：
yum install elfutils-libelf-devel
2. make CONFIG_BLK_DEV_NBD=m M=drivers/block
錯誤：
drivers/block/nbd.c: 在函數‘__nbd_ioctl’中:
drivers/block/nbd.c:619:19: 錯誤：‘REQ_TYPE_SPECIAL’未聲明(在此函數內第一次使用)
sreq.cmd_type = REQ_TYPE_SPECIAL;
^
drivers/block/nbd.c:619:19: 附註：每個未聲明的標識符在其出現的函數內只報告一次
make[1]: *** [drivers/block/nbd.o] 錯誤 1
make: *** [_module_drivers/block] 錯誤 2
解決：
1、 REQ_TYPE_SPECIAL變量是在/usr/src/kernels/3.10.0-514.26.2.el7.x86_64/include/linux/blkdev.h文件中定義，由代碼可知 REQ_TYPE_SPECIAL = 7：
/*
* request command types
*/
enum rq_cmd_type_bits {
REQ_TYPE_FS = 1, /* fs request */
REQ_TYPE_BLOCK_PC, /* scsi command */
REQ_TYPE_SENSE, /* sense request */
REQ_TYPE_PM_SUSPEND, /* suspend request */
REQ_TYPE_PM_RESUME, /* resume request */
REQ_TYPE_PM_SHUTDOWN, /* shutdown request */
#ifdef __GENKSYMS__
REQ_TYPE_SPECIAL, /* driver defined type */
#else
REQ_TYPE_DRV_PRIV, /* driver defined type */
#endif
/*
* for ATA/ATAPI devices. this really doesn't belong here, ide should
* use REQ_TYPE_DRV_PRIV and use rq->cmd[0] with the range of driver
* private REQ_LB opcodes to differentiate what type of request this is
*/
REQ_TYPE_ATA_TASKFILE,
REQ_TYPE_ATA_PC,
};
2、修改drivers/block/nbd.c，在619行將sreq.cmd_type直接定義爲7
//sreq.cmd_type = REQ_TYPE_SPECIAL;
sreq.cmd_type = 7;