Analysis of the U disk can not start the reason

different BIOS for u disk (USB-HDD mode) startup, the same U disk capacity parameters---cylinder, head and number of sectors (referred to as CHS), the identification of different (prove this can be installed on different machines on the same version of Linux, and then insert a U disk, using hdparm/dev/ SDA commands can be found CHS different machines, even if the U disk can be started with grub, in grub using the geometry (hd0) command can also be seen), This way the partition table and the Fat disk parameter table produced by the partitioning of a machine are expressed according to the CHS of the hard disk identified by this machine, and the CHS of the other machine is different when it is changed to another machine, which causes confusion.

Fortunately, the partition table and the Fat disk parameter table also have a way of expressing the relative number of sectors, and this expression is also recorded in the partition table and the disk parameter table. This depends on what kind of data the software uses to work, if the use of CHS, then a machine will not work properly, if the use of LBA access to the disk will not be affected---of course, the prerequisite is that the BIOS supports the USB disk using LBA mode access that extends INT13h. and XP to FAT16 file system partition format generated MBR code and DOS versions are dependent on the CHS work, so the usual method in a machine-made boot U disk in another machine startup may not be successful. The tested mobile hard disk in the BIOS of the CHS is consistent, and the hard disk directly connected to the IDE port CHS the same, so the mobile hard drive USB boot is basically not difficult.

What I have found is really affected by this problem, which affects the startup program:

1. MBR written when Windows XP and SP1 Chinese disk Manager partitions

2, Usboot produced MBR and boot (same as 1)

3. Install GRLDR.MBR from Grub for DOS 0.41 to MBR using bootlace.com

Procedures that may not be affected by this problem are (not adequately tested):

1, NTLDR and subsequently launched the PE or XP environment (of course, otherwise u disk will not be able to use)

2, Linux under the INSTALL-MBR program written by the MBR

3. GNU GRUB 0.95 and 0.97 and their boot code installed using the Grub-install command

4, syslinux3.36 and 3.51

5, linux2.4 kernel above, basically Linux system All programs to FAT file system will not use CHS

6, Grub CHS 0.95 0.97 (contains Stage1, stage1.5 and stage2 boot code)