U disk HDD mode 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

MBR written by Fdisk 2, DOS5, 6, 6.22, Win95

3, DOS5, 6, 6.22, Win95 of the format written in the boot

4, including Windows95 98SE of all MS DOS Io.sys (all need to rely on CHS to identify the FAT file system)

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

6. 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, Win98, 98SE MBR written by Fdisk

2, Win98, 98SE of the format write boot (requires that the FAT16 partition type must be 0XE to support LBA)

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

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

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

6, syslinux3.36 and 3.51

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

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

　　So the solution to this problem is the corresponding:

1, forced U disk to Usb-cdrom, usb-floppy or Usb-zip way to start, so that the BIOS has the standard to follow, it will not "speak from the words", this is the current use of U disk mass production tools of the basic ideas, but this let no mass production tool SD card + Reader's combination of disappointment, and most of the current large capacity u disk are no write protection switch or read and write speed is not ideal, and sometimes need high-speed SD card + reader combination;

2, the use of active hard disk boot basically no problem.

3. Boot loader with no error CHS parameters, such as GNU grub or syslinux boot, or any other combination. Chinese cabbage website

Here's what I've tried to do with the GNU GRUB, Grub CHS, and Grub for DOS:

　　Method One: Full use of grub Chinese version of Stage1, stage1.5, Stage2 startup

1, find a normal running GNU GRUB0.95 or 0.97 machine (Redhat ELAS4 update0-update6,elas5 update0-update1)

2, the Grub_for_dos-0.4.1.zip in the Chinese/boot/grub stage1, 1.5, 2 files into the Linux/usr/share/grub (here different versions may grub stage Image where the path is different,/usr/share/grub is most of the case, pay attention to the original file backup.

3, insert to do to start the U disk or mobile hard disk, to partition, because there are some BIOS to USB-HDD only support CHS mode, thus restricting the boot partition can not exceed 1023*16*63 sector, so for the general, the boot partition not more than 511M, the type is 0xe, ( Read Win98SE's DOS 7.1 boot boot code found that DOS 7.1 uses 0xe this type to support an LBA-enabled boot, and its file access may also use this flag, although it may not be used for grub, but if the multiple boot contains DOS 7.1, it works. Set the boot flag to be formatted as a FAT16 file system. It's all done under Linux. (Corrected December 29)

4. Mount the boot partition into the/MNT

5, Grub-install--ROOT-DIRECTORY=/MNT/DEV/SDX, note that you must not choose--force-lba, because of the grub under Linux now and Stagex does not match, the machine will not start

6, ignore/mnt/boot/grub/device.map file, this file is Grub-install program use, after installation is useless.

7, umount/mnt and restore/usr/share/grub content

This allows you to leave a regret because the--FORCE-LBA option is not enabled, so the next step is to start using this device, under the GRUB command line:

1, Root (hd0,0), where to specify stage image file source

2, Setup--force-lba (hd0), to install, this grub Chinese version has been fully installed in the MBR.

This is the method I used initially, but now the grub Chinese version has stopped updating, so this method is not recommended.

　　Method Two: Load grub for DOS with GNU GRUB Boot

1, find the latest stable version of Linux, such as Redhat ELAS5 Update1, direct its GNU grub plus--force-lba option installed in the U disk MBR (can refer to one, pay attention not to overwrite those files, and do not forget to set the partition type to 0XE).

2, the Grub_for_dos-0.4.2.zip in the chinese/grub.exe copy to the U disk root directory.

3. Use the GNU Grub Boot to boot the grub.exe with the Kernel/grub.exe and boot commands so you can enjoy the grub for DOS Chinese menu and direct support for NTLDR, Io.sys startup features.

This approach is good at always using the latest and most stable GNU grub to deal with the buggy BIOS while still enjoying the convenience of the grub for DOS Chinese version. This way on my machine, whether it's PE or DOS, startup speed is quite slow, even the menu display speed is surprisingly slow, and not only the startup process, even after the launch of the successful operation of other programs is very slow, I think it is grub for DOS Chinese version of the reason, tried grub for DOS Chinese version 0.41, 0.42 and 0.43 are not ideal.

　　Method Three: Use the GNU Grub Stage1, stage1.5 and Grub 0.97 Chinese version of the Stage2 hybrid boot

1, find the latest stable version of Linux, such as Redhat ELAS5 Update1, direct its GNU grub plus--force-lba option installed in the U disk MBR (can refer to one, pay attention not to overwrite those files, and do not forget to set the partition type to 0XE).

2, the use of Grub_for_dos-0.4.1.zip in Chinese/boot/grub stage2 file replace the U disk in/boot/grub/stage2

This method has the advantage of two and is faster to start, and the disadvantage is that this is not the usual practice, and it is not necessarily feasible after the GNU Grub version is updated, but it seems that GNU Grub has also stopped updating:-). In the present case, the individual recommends this method.

Other attempts: Using Syslinux to boot grub for dos0.41, 0.42, and 0.43 Grub.exe was also successful, but was slow to start and run as method two

　　Actual application test:

Now my own tool plate (150-speed original 2G SD card + chuanyu 150X SDHC Reader, digression: This card reader in addition to support 150 speed other than really garbage) is the use of method three production, in the actual environment has not been found unable to start the phenomenon. These include HP Dl380g3, G4, DL580, Dell 3850, 6850, IBM X345, 346, 3650, and, of course, my desktop and laptop computers.

Here to add that: this is only the impact of a U disk USB-HDD way to start a number of factors, one of the important factors of the exploration, the mirror is only relatively popular practice has been improved to improve the U disk on different machines to start the success of the possibility, And can not be said to solve the U disk USB-HDD way to start all problems. Originally as a research post is just want to provide methods do not want to provide specific products, but take into account a variety of factors, or put out for everyone to test it.

Because ghost in the recovery will be more than the partition type to 06, so I used Winhex generated a 1:1 u disk mirror for research, uncompressed file name is u-1gboot.img. This boot disk to compress the volume, only a fake boot menu, as long as the start of this menu is successful.

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