As following the manual of LFS and two weeks researching, finally build up my first LFS successfully. In the "8.4. Making the LFS System Bootable", when I issue "grub> setup (hd0)". it says
grub> setup (hd0)Segmentation fault
I fix this by using the "original" grub programs,
mount /dev/hda1 /mnt/c
grub> root (hd0,2)
Later, the LFS can boot, while it seems slowly to keyboard response. I will follow up with this. Whatever, first successful building makes me very excited. It's really interesting!