What are the options for booting from usb when the legacy boot option is not supported by the bios?

Question

On a Dell Inspiron 3493 laptop with a Windows 10, 64 bit preinstalled, I have tried to test some Linux distributions (Linux Mint 19.3 Cinnamon 32 bit, Linux Lite 64 bit last version). I created bootable usb by RUFUS.

Unfortunately, by pressing F12 at startup, the option for booting from usb is not shown. By pressing F12, two options appear as UeFI boot devices: 1- Windows boot manager, 2- UEFI hard drive, by pressing both option the Windows 10 is started.

I have tested many options in the bios (for example, disabling secure boot) but the usb boot option does not appear

In the bios, it is noted that "the legacy boot option is not supported on this platform". If that matters, the bios exactly looks like the one given in this video https://www.youtube.com/watch?v=Kv82a1-TyqU

I cannot use the answers given in Booting from USB when BIOS doesn't support it? because the device does not have CD DVD rom drive.

Solution

The options are:

1. Use an UEFI-bootable Linux image.

UEFI is certainly not incapable of booting from CDs and external disks. However, you're probably aware that it uses a different bootloader format than BIOS did – it doesn't boot from MBR, it wants an .efi file on a FAT partition – and the same applies to USB sticks just as well as it does for internal drives.

So it's generally up to the distro to ensure that their provided USB stick images are UEFI bootable in addition to being BIOS bootable, and even today not all distributions do that! For example, Arch and Ubuntu are UEFI-compatible but Slax is not.

Make sure the USB stick has a file \EFI\Boot\Bootx64.efi, which will be used as the bootloader for removable drives.

If you're building the bootable USB locally (using Rufus), then you must enable UEFI support in Rufus as well. There's a drop-down list where you need to select "Target system: UEFI" or "BIOS and UEFI" – this will make sure the correct filesystem type is used, etc. Again, afterwards make sure the Bootx64.efi file is present at the correct location.

Comments

[user1686]

Which Linux distribution is that, and what tools did you use to build the bootable USB stick?

[Name]

@user1686 I added the info.

[user1686]

Did you enable UEFI support in Rufus, then?

[harrymc]

There is a very new BIOS for your model dating from just 12 days ago. You might have better luck with it.

[Name]

@user1686 when I use Refus the options are: Partition scheme=MBR, Target system=BIOS (or UEFI-CSM), File system=Fat32, Cluster Size=4096. I can only change File system and Cluster Size, other options are not changable. I use the last version of Rufus.

[user1686]

Sounds like it has detected that the original image itself is not UEFI-bootable, then. Try a different distribution, e.g. Ubuntu or Fedora.

[Name]

@harrymc Thank you for the link. Indeed I have installed a newest BIOS dell.com/support/home/us/en/04/drivers/… newer than the one given in your link (just 4 days ago) but I have the same problem.

[Name]

@user1686 I will try your suggestion and I will come back.

[user1686]

I'm calling [citation needed] on "you cannot boot into an OS that was installed using Secure Boot". That hasn't been true for any Windows install that I've messed with so far...

[LPChip]

@user1686 I've done many installs and turning off secure boot lead me to not being able to boot into windows if windows was installed using secure boot. If secureboot is turned off, you install windows, then turn secure boot on, your istallation will keep working in non-secure mode though, and you can turn it on or off at will.

[Name]

Thank you, I confirm that this solved my problem. By using UEFI-bootable Linux image, and selecting GPT partition scheme and UEFI (non CSM) target system, the bootable usb actually appears in boot menu. As you mentioned, not all Linux distributions provide a UEFI compatible iso, some of them provide, for example Ubuntu and Linux Mint 19.3, 64 bit.