Introduction
There may be many reasons to create a bootable USB flash drive with an installed bootloader. Not all live CD's of popular distros contain hybrid MBR/El-Torito bootable sectors. So if you are trying to write the ISO image directly into the flash drive using:
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$ sudo dd if=Ubuntu-10.04-desktop-i386.iso of=/dev/sdb |
then it won't help. The flash drive won't boot, because BIOS sees it as a hard disk and requires bootstrap code in the Master Boot Record (MBR) of the drive. However, the ISO image relies on the "El Torito bootable CD specification" according to which BIOS boots sector #17 (sector size is 2048 bytes) of the CD.
On contrary, GRUB bootloader, when properly tuned, is capable of loading some of the Linux distributions directly from the ISO image stored on the drive. It cannot boot all ISO files, but at least ArchLinux and Ubuntu seem to be bootable.
In addition, with the help of memdisk utility of the SYSLINUX bootloader it can load any ISO/floppy disk image of sufficiently small size directly to RAM and chainload the boot process. This method can be used to boot exotic operating systems such as Kolibri, MenuetOS, DixOS which are written in assembly language. Booting small Linux-based distros such as Tinfoil Hat Linux and Tiny Core Linux in the RAM disk is also possible. The only prerequisite is a sufficiently large RAM size of the computer.
Also it should be mentioned that GRUB provides a minimal shell environment, and acts like a small operating system. It is capable of reading data from many operating systems and even displaying graphic images of the JPEG and PNG format.
Moreover, a flash drive formatted with NTFS file system can be used as a USB stick for storing and transferring data between computers (especially for those which are running Windows OS). This is actually the main function of the flash drive in a daily life.
Prerequisites
An IBM-compatible PC, the Arch Linux operating system, a flash drive recognized as /dev/sdb (do not accidentally overwrite your main hard disk), QEMU virtual machine (optional).
Installing Necessary Packages
First of all back up your data on your flash drive. Install necessary packages.
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sudo pacman -S parted syslinux grub ntfs-3g qemu |
Partitioning the Drive
Now you can partition the drive despite all warnings and non-optimal behavior of small 512 byte long sectors. Here intention is different. First of all, a lot of people have ever wondered how do the 446 bytes of the bootstrap code found in the MBR can magically locate the partition and load some files from the file system of that partition? The whole file system input/output is needed! And this requires several kilo-bytes of memory. Usually bootloaders store this code in the MS-DOS compatibility region (62 sectors of size 512 bytes each located right after the MBR, i.e. of total size 31 KB). So what happens if we create a partition table without MS-DOS compatibility region? GRUB will be able to load its core image directly using only MBR's bootstrap code without any file system driver! This method is called "blocklists" method. Here is the proof. We will create a primary partition starting right after the MBR:
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$ sudo parted /dev/sdb (parted) rm 1 # remove partition 1 if such exists (parted) mktable msdos # make MS-DOS partition table (parted) help mkpart (parted) print devices (parted) print free (parted) mkpart primary ntfs 1s -1s # make a primary partition starting at sector 1 (right after the MBR) and ending at the very last sector Warning: The resulting partition is not properly aligned for best performance. Ignore/Cancel? Ignore # type "Ignore" (parted) set 1 boot on # set bootable flag (parted) quit |
Formatting the Partition
Format the first partition with NTFS file system and label it as "BootableUSB":
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$ sudo mkfs.ntfs -v -Q -L "BootableUSB" /dev/sdb1 |
Checking the MBR
Now check the Master Boot Record (MBR) for the "55 AA" word at the end of the sector:
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$ sudo dd if=/dev/sdb bs=512 count=1|hexdump -C 1+0 records in 1+0 records out 512 bytes (512 B) copied, 3.8609e-05 s, 13.3 MB/s 00000000 eb 63 90 10 8e d0 bc 00 b0 b8 00 00 8e d8 8e c0 |.c..............| 00000010 fb be 00 7c bf 00 06 b9 00 02 f3 a4 ea 21 06 00 |...|.........!..| 00000020 00 be be 07 38 04 75 0b 83 c6 10 81 fe fe 07 75 |....8.u........u| 00000030 f3 eb 16 b4 02 b0 01 bb 00 7c b2 80 8a 74 01 8b |.........|...t..| 00000040 4c 02 cd 13 ea 00 7c 00 00 eb fe 00 00 00 00 00 |L.....|.........| 00000050 00 00 00 00 00 00 00 00 00 00 00 80 09 e5 53 00 |..............S.| 00000060 00 00 00 00 ff fa 90 90 f6 c2 80 74 05 f6 c2 70 |...........t...p| 00000070 74 02 b2 80 ea 79 7c 00 00 31 c0 8e d8 8e d0 bc |t....y|..1......| 00000080 00 20 fb a0 64 7c 3c ff 74 02 88 c2 52 be 80 7d |. ..d|<.t...R..}| 00000090 e8 17 01 be 05 7c b4 41 bb aa 55 cd 13 5a 52 72 |.....|.A..U..ZRr| 000000a0 3d 81 fb 55 aa 75 37 83 e1 01 74 32 31 c0 89 44 |=..U.u7...t21..D| 000000b0 04 40 88 44 ff 89 44 02 c7 04 10 00 66 8b 1e 5c |.@.D..D.....f..\| 000000c0 7c 66 89 5c 08 66 8b 1e 60 7c 66 89 5c 0c c7 44 ||f.\.f..`|f.\..D| 000000d0 06 00 70 b4 42 cd 13 72 05 bb 00 70 eb 76 b4 08 |..p.B..r...p.v..| 000000e0 cd 13 73 0d f6 c2 80 0f 84 d8 00 be 8b 7d e9 82 |..s..........}..| 000000f0 00 66 0f b6 c6 88 64 ff 40 66 89 44 04 0f b6 d1 |.f....d.@f.D....| 00000100 c1 e2 02 88 e8 88 f4 40 89 44 08 0f b6 c2 c0 e8 |.......@.D......| 00000110 02 66 89 04 66 a1 60 7c 66 09 c0 75 4e 66 a1 5c |.f..f.`|f..uNf.\| 00000120 7c 66 31 d2 66 f7 34 88 d1 31 d2 66 f7 74 04 3b ||f1.f.4..1.f.t.;| 00000130 44 08 7d 37 fe c1 88 c5 30 c0 c1 e8 02 08 c1 88 |D.}7....0.......| 00000140 d0 5a 88 c6 bb 00 70 8e c3 31 db b8 01 02 cd 13 |.Z....p..1......| 00000150 72 1e 8c c3 60 1e b9 00 01 8e db 31 f6 bf 00 80 |r...`......1....| 00000160 8e c6 fc f3 a5 1f 61 ff 26 5a 7c be 86 7d eb 03 |......a.&Z|..}..| 00000170 be 95 7d e8 34 00 be 9a 7d e8 2e 00 cd 18 eb fe |..}.4...}.......| 00000180 47 52 55 42 20 00 47 65 6f 6d 00 48 61 72 64 20 |GRUB .Geom.Hard | 00000190 44 69 73 6b 00 52 65 61 64 00 20 45 72 72 6f 72 |Disk.Read. Error| 000001a0 0d 0a 00 bb 01 00 b4 0e cd 10 ac 3c 00 75 f4 c3 |...........<.u..| 000001b0 00 00 00 00 00 00 00 00 0c 61 0e 00 00 00 00 00 |.........a......| 000001c0 02 00 07 de 77 e7 01 00 00 00 ff 97 77 00 00 00 |....w.......w...| 000001d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 000001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa |..............U.| |
Checking the VBR
Similarly, check the Volume Boot Record (VBR) of the first partition for the "55 AA" word at the end of the sector. In our setup that VBR is located right after the MBR (option "skip=1" of the "dd" command):
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$ dd if=/dev/sdb bs=512 count=1 skip=1|hexdump -C 1+0 records in 1+0 records out 512 bytes (512 B) copied, 3.7795e-05 s, 13.5 MB/s 00000000 eb 52 90 4e 54 46 53 20 20 20 20 00 02 08 00 00 |.R.NTFS .....| 00000010 00 00 00 00 00 f8 00 00 3e 00 7c 00 01 00 00 00 |........>.|.....| 00000020 00 00 00 00 80 00 80 00 fe 97 77 00 00 00 00 00 |..........w.....| 00000030 04 00 00 00 00 00 00 00 7f 79 07 00 00 00 00 00 |.........y......| 00000040 f6 00 00 00 01 00 00 00 5a 50 80 73 94 60 16 3a |........ZP.s.`.:| 00000050 00 00 00 00 fa 33 c0 8e d0 bc 00 7c fb 68 c0 07 |.....3.....|.h..| 00000060 1f 1e 68 66 00 cb 88 16 0e 00 66 81 3e 03 00 4e |..hf......f.>..N| 00000070 54 46 53 75 15 b4 41 bb aa 55 cd 13 72 0c 81 fb |TFSu..A..U..r...| 00000080 55 aa 75 06 f7 c1 01 00 75 03 e9 d2 00 1e 83 ec |U.u.....u.......| 00000090 18 68 1a 00 b4 48 8a 16 0e 00 8b f4 16 1f cd 13 |.h...H..........| 000000a0 9f 83 c4 18 9e 58 1f 72 e1 3b 06 0b 00 75 db a3 |.....X.r.;...u..| 000000b0 0f 00 c1 2e 0f 00 04 1e 5a 33 db b9 00 20 2b c8 |........Z3... +.| 000000c0 66 ff 06 11 00 03 16 0f 00 8e c2 ff 06 16 00 e8 |f...............| 000000d0 40 00 2b c8 77 ef b8 00 bb cd 1a 66 23 c0 75 2d |@.+.w......f#.u-| 000000e0 66 81 fb 54 43 50 41 75 24 81 f9 02 01 72 1e 16 |f..TCPAu$....r..| 000000f0 68 07 bb 16 68 70 0e 16 68 09 00 66 53 66 53 66 |h...hp..h..fSfSf| 00000100 55 16 16 16 68 b8 01 66 61 0e 07 cd 1a e9 6a 01 |U...h..fa.....j.| 00000110 90 90 66 60 1e 06 66 a1 11 00 66 03 06 1c 00 1e |..f`..f...f.....| 00000120 66 68 00 00 00 00 66 50 06 53 68 01 00 68 10 00 |fh....fP.Sh..h..| 00000130 b4 42 8a 16 0e 00 16 1f 8b f4 cd 13 66 59 5b 5a |.B..........fY[Z| 00000140 66 59 66 59 1f 0f 82 16 00 66 ff 06 11 00 03 16 |fYfY.....f......| 00000150 0f 00 8e c2 ff 0e 16 00 75 bc 07 1f 66 61 c3 a0 |........u...fa..| 00000160 f8 01 e8 08 00 a0 fb 01 e8 02 00 eb fe b4 01 8b |................| 00000170 f0 ac 3c 00 74 09 b4 0e bb 07 00 cd 10 eb f2 c3 |..<.t...........| 00000180 0d 0a 41 20 64 69 73 6b 20 72 65 61 64 20 65 72 |..A disk read er| 00000190 72 6f 72 20 6f 63 63 75 72 72 65 64 00 0d 0a 42 |ror occurred...B| 000001a0 4f 4f 54 4d 47 52 20 69 73 20 6d 69 73 73 69 6e |OOTMGR is missin| 000001b0 67 00 0d 0a 42 4f 4f 54 4d 47 52 20 69 73 20 63 |g...BOOTMGR is c| 000001c0 6f 6d 70 72 65 73 73 65 64 00 0d 0a 50 72 65 73 |ompressed...Pres| 000001d0 73 20 43 74 72 6c 2b 41 6c 74 2b 44 65 6c 20 74 |s Ctrl+Alt+Del t| 000001e0 6f 20 72 65 73 74 61 72 74 0d 0a 00 00 00 00 00 |o restart.......| 000001f0 00 00 00 00 00 00 00 00 80 9d b2 ca 00 00 55 aa |..............U.| |
Note that
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$ sudo dd if=/dev/sdb1 bs=512 count=1|hexdump -C |
should give the same result since /dev/sdb1 starts from the VBR.
Installing GRUB into the MBR
Mount the first partition of the flash memory and install GRUB into the MBR using blocklists method:
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$ sudo mkdir /mnt/USB $ sudo mount /dev/sdb1 /mnt/USB $ sudo grub-install --target=i386-pc --recheck --force --no-floppy --boot-directory=/mnt/USB /dev/sdb /usr/bin/grub-bios-setup: warning: this msdos-style partition label has no post-MBR gap; embedding won't be possible. /usr/bin/grub-bios-setup: warning: Embedding is not possible. GRUB can only be installed in this setup by using blocklists. However, blocklists are UNRELIABLE and their use is discouraged.. Installation finished. No error reported. |
If you have a 64-bit system, change the target value "--target=x86_64-pc".
Configuring GRUB
Now create GRUB configuration file:
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$ sudo nano /mnt/USB/grub/grub.cfg |
and paste the following content:
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insmod part_msdos insmod ntfs set timeout=10 set default=1 function load_video { if [ x$feature_all_video_module = xy ]; then insmod all_video else insmod efi_gop insmod efi_uga insmod ieee1275_fb insmod vbe insmod vga insmod video_bochs insmod video_cirrus fi } if loadfont unicode ; then set gfxmode="800x600x32" load_video insmod gfxterm terminal_input console terminal_output gfxterm fi insmod gfxmenu #loadfont /grub/themes/starfield/dejavu_10.pf2 #loadfont /grub/themes/starfield/dejavu_12.pf2 #loadfont /grub/themes/starfield/dejavu_14.pf2 #loadfont /grub/themes/starfield/dejavu_16.pf2 #loadfont /grub/themes/starfield/dejavu_bold_14.pf2 #insmod jpeg #background_image /grub/image.jpeg #set theme=/grub/themes/starfield/theme.txt #export theme terminal_input at_keyboard #keymap /grub/tr.gkb insmod memdisk set pager=1 menuentry "ArchLinux x86_64, June 2013" { set isofile="/System/archlinux-2013.06.01-dual.iso" loopback loop $isofile linux (loop)/arch/boot/x86_64/vmlinuz isofrom=$isofile archisolabel="ARCH_201306" img_dev=/dev/disk/by-label/BootableUSB img_loop=$isofile initrd (loop)/arch/boot/x86_64/archiso.img } menuentry "ArchLinux i686, June 2013" { set isofile="/System/archlinux-2013.06.01-dual.iso" loopback loop $isofile linux (loop)/arch/boot/i686/vmlinuz isofrom=$isofile archisolabel="ARCH_201306" img_dev=/dev/disk/by-label/BootableUSB img_loop=$isofile initrd (loop)/arch/boot/i686/archiso.img } menuentry "Ubuntu-13.04-desktop-amd64.iso" { set isofile="/System/ubuntu-13.04-desktop-amd64.iso" loopback loop $isofile linux (loop)/casper/vmlinuz.efi boot=casper iso-scan/filename=$isofile quiet noeject noprompt splash -- initrd (loop)/casper/initrd.lz } menuentry "Tinfoil Hat Linux (using memdisk)" { linux16 /grub/memdisk iso initrd16 "/System/tinfoil.img" } menuentry "Micro-Core Linux (using memdisk)" { linux16 /grub/memdisk iso initrd16 "/System/microcore-current.iso" } menuentry "G4L Hard Disk and Partition Imaging and Cloning tool (using memdisk)" { linux16 /grub/memdisk iso initrd16 "/System/g4l-v0.43.iso" } |
Installing the Memdisk Module
Simply copy the memdisk file to your GRUB folder:
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$ sudo cp /usr/lib/syslinux/memdisk /mnt/USB/grub |
Downloading the ISO/Floppy Images
Now you can download the ISO/floppy images of the operating systems listed in
"/mnt/USB/grub/grub.conf" (i.e. ArchLinux, Ubuntu, Tinfoil Hat Linux, Micro-Core Linux and G4L partitioning utility) and put them into "/mnt/USB/System/" folder.
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$ sudo mkdir /mnt/USB |
/System
Testing the Bootable USB Disk
Now you can unmount the USB disk:
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$ sudo umount /mnt/USB |
and test it in the QEMU virtual machine:
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$ sudo qemu-system-i386 -usb /dev/sdb |
Instead of "qemu-system-i386" you can use "qemu-system-x86_64".
Hopefully you will get the following screen:
Now unplug the flash drive and test it on the real hardware.