vagrant 开始正常升级GCC版本以后失败 

/sbin/mount.vboxsf: shared folder '/home/vagrant/go' was not found (check VM settings / spelling)

1.virtualBox  挂在iso

2.挂载文件

sudo su

mkdir /mnt/cdrom

mount /dev/cdrom /mnt/cdrom

cd /mnt/cdrom

./VBoxLinuxAdditions.run

3.如果缺失so库 安装即可