grub>rootnoverify (hd0,0)--->win7系统安装盘号
grub > chainloader +1
grub > makeactive --->激活主分区
grub > boot
rootnoverify(hd0,4)、chainloader +1” means
If you want to boot an unsupported operating system (e.g. Windows 95), chain-load a boot loader for the operating system. Normally, the boot loader is embedded in the "boot sector " of the partition on which the operating system is installed.
rootnoverify(hd0,4):Set GRUB 's root device to the partition
chainloader +1:Load the boot loader, `+1 ' indicates that GRUB should read one sector from the start of the partition
root指定根分区并挂载，rootnoverify指定根分区但不挂载之。
举例来说：在grub中要引导windows系统，就可以指定windows所在分区，但不用挂载，比如：
grub>rootnoverify (hd0,1)
grub>chainloader +1
grub>boot
而要进入linux系统，就需要挂载，如：
grub>root (hd0,5)