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I extract "ubuntu-17.10-desktop-amd64.iso" and copy it to a FAT32 filesystem USB flash. My computer can boot from USB flash. but when I change the filesystem to NTFS/exFAT, it can't boot.

Is it poss possible to extract raspbian.img to a FAT SD card, and then boot from raspberrypi?

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2 Answers 2

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There are three things here:

  1. Older BIOS firmware in a PC needed a MBR in order to boot. It looks at a specific place for boot code and excecures that. MBR+FAT and MBR+NTFS should work both since the firmware loads only the MBR/bootloader paret. After that is is the bootloader which needs to understand the filesystem.
  2. Modern PC firmware used UEFI. EIFI does not use a bootloader. Instead if looks for an EFI System partition (ESP). This partition must be in a format which the firmware understands. It is mandatory to understand a format which just happens to be 100% compatible with FAT.*.
    The firmwate that either starts a boot program, or if none are set fals back to /boot/bootx64.EFI.

Now as I understand you question it is:

  1. I have a PC with UEFI firmware (and not BIOS firmware)
  2. I want to boot in UEFI mode.

Why do I need an EFI copmpatible fielsystem (FAT).

The answer should be clear with above background :)



And for completeness sake:

  • It is perfectly possible to load a Linux installer on an ext2 formatted pendrive with MBR in an older BIOS system or in an EFI system with ancient backward compatability shims enabled.
  • BIOS(UEFI mode) does not exist. Firmware (BIOS), firmware (UEFI) exist. And this can be firmware (UEFI) with CSM enabled, sort of acting like BIOS. It is not BIOS however. And often the shims are incomplete.

*: The firmware is allowed to understand more format. And the EFI on some apple systems understands HFS. But most systems implement the bare minumum. Which happens to be a rebranded FAT format.

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  • Can I extract the raspbian.img to a SDcard(FAT) to run raspbian OS on raspberrypi?
    – Aoxiang
    Nov 22, 2017 at 15:16
  • Why not install it to an SD card? Format it ext2/3/4 (or whatever is normal these days. Add MBR, boot in legagy mode or create partitions for ESP, /, /var/ /tmp/ /home, /usr, /usr/local and whatever is used these days. My linux days are sadly gone. Merely experience with UEFI, win 10 and vmwqre workstation running my comfy linuxes and BSDs).
    – Hennes
    Nov 22, 2017 at 17:16
  • I mean just extrat Raspbian.img and copy it to SDcard. But the raspberrypi website recommen use win32DiskImager tool to write the img file to SD card. If win10 provide a way to write img file to SDcard, I don't want to use a tool.
    – Aoxiang
    Nov 23, 2017 at 6:57
  • What is EIFI? I suspect you mean UEFI. Your statement that UEFI does not use a bootloader is factually incorrect. UEFI firmware contains a builtin bootloader.
    – fpmurphy
    Nov 27, 2017 at 1:23
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No, it is not necessary for the flash drive to be FAT to be bootable but as it stands now most devices are able to recognize natively FAT32 format be it your droid,tv or something else. However you can boot from any format as long as your bootloader recognizes it.

Took this from here: https://askubuntu.com/questions/678083/must-the-flash-drive-be-fat-to-be-bootable

I think myself that your bootloader does not recognise the format. Or maybe there is boot mode in your bios that needs to be properly set.

Because i tried myself making a NTFS bootloader for Win7 Pro 64bit and it worked out fine.

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  • This doesn't answer the question. The OP asks for UEFI, but MBR+bootloader which you explain pertains to BIOS only.
    – Tonny
    Nov 22, 2017 at 12:45

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