grub 启动参数
ro: Mount the root device read-only on boot
root=UUID=866f85ce-0e10-424b-a329-19f3bebeacb8: Specify the root filesystem to boot from(/sbin/init 所在分区)
nomodeset: Disable Kernel Mode Setting(点击打开链接)
rd_NO_LUKS
KEYBOARDTYPE=pc
KEYTABLE=us
rd_NO_MD
crashkernel=128M: Reserve a portion of physical memory for kexec to use
LANG=zh_CN.UTF-8
rd_NO_LVM
rd_NO_DM
rhgb: redhat graphical boot - This is a GUI mode booting screen with most of the information hidden while the user sees a rotating activity icon spining and brief information as to what the computer is doing.
quiet: hides the majority of boot messages before rhgb starts. These are supposed to make the common user more comfortable. They get alarmed about seeing the kernel and initializing messages, so they hide them for their comfort. rtlinux中需要此选项，防止输出内容到vga终端下（ctrl alt 1 2 3等打开的字符界面），否则延迟很大。
