make the LBA support bitmap checks configurable at the installation time.

docs/grub-install.8

@@ -20,6 +20,10 @@ instead of the root directory.
 .TP
 \fB\-\-grub\-shell\fR=\fIFILE\fR
 use FILE as the grub shell.
+.TP
+\fB\-\-force\-lba\fR
+Force GRUB to use LBA mode even for a buggy
+BIOS.
 .PP
 INSTALL_DEVICE can be a GRUB device name or a system device filename.
 .PP