BIOS Setting to boot USB UEFI stick

Hello,

Connect the stick to usb port and reboot the system (or turn it on) as soon as you see the Dell logo tap F12 in the menu that appaers choose your stick.

The answer above is correct. On UEFI systems, the boot order list for local storage devices only includes paths that have been formally registered into the firmware, which is typically done during OS installation. Temporarily attached devices like flash drives are accessed through the F12 one-time boot menu. Technically you could register the \EFI\Boot\Bootx64.efi bootloader file on that flash drive as a permanent boot device, but you may not want to.

Hello !

After some fiddling with USB sticks and settings, I finally found the answer. I did "pure" USB stcks, I.E. with GPT partition tables and EFI boot executable.

I is not working. But when you partition your stick with MSDOS (or MBR as it is sometimes called) the stick is detected and if the boot is set to UEFI on the stick, it is listed on the UEFI boot list.

So I've found the "workaround" or the logic behind the Dell boot BIOS.

Thanks for your help.

Have a nice day.

FYI MSDOS and MBR are not interchangeable terms at all. MBR has nothing to do with DOS. But yes, a UEFI system can boot in UEFI mode from either GPT or MBR USB devices as long as the partition is formatted FAT32 and the UEFI bootloader file is there. GPT is more common, but MBR does work, and can be useful if you want to make a single USB device that’s bootable for both Legacy BIOS and UEFI systems. Glad you found a workaround.

FYI MSDOS and MBR are not interchangeable terms at all. MBR has nothing to do with DOS. But yes, a UEFI system can boot in UEFI mode from either GPT or MBR USB devices as long as the partition is formatted FAT32 and the UEFI bootloader file is there. GPT is more common, but MBR does work, and can be useful if you want to make a single USB device that’s bootable for both Legacy BIOS and UEFI systems. Glad you found a workaround.

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@m0dul8r  GPT is a partition layout scheme for the entire disk (the other option is MBR), whereas FAT32 is a file system for a partition (other options include NTFS, exFAT, etc.)  You can have a GPT flash drive that uses a FAT32 partition or an MBR flash drive that uses a FAT32 partition.  GPT and FAT32 aren't "opposite".  And you can absolutely use a GPT-initialized disk to boot in UEFI mode from USB devices.  I do it all the time, and in fact UEFI is explicitly intended to boot from GPT devices.  It also supports booting from MBR-initialized devices for backward compatibility, but it's fine with GPT.

Spanning WIMs can be a problem because the Windows Setup interface won't allow you to select images that reside in a spanned WIM, so if you use a spanned WIM you'd need to apply the image to the disk manually using a tool like DISM -- but most people don't know how to do that.  If I have a WIM that's larger than 4GB, I use Rufus to create a specially prepared flash drive that uses an NTFS partition for the main data but also contains a small FAT partition that stores a UEFI NTFS driver.  That way, when I boot the system in UEFI mode, it initially boots from the FAT partition, loads the UEFI NTFS driver, and then turns around and boots from whatever is on the NTFS partition.  It works brilliantly.  The only catch is that you have to disable Secure Boot because the bootloader for the NTFS driver is provided under an open source license and Microsoft therefore won't sign the bootloader so that it's trusted under Secure Boot.  But you can re-enable Secure Boot after you've installed whatever OS you're installing.

@m0dul8r  GPT is a partition layout scheme for the entire disk (the other option is MBR), whereas FAT32 is a file system for a partition (other options include NTFS, exFAT, etc.)  You can have a GPT flash drive that uses a FAT32 partition or an MBR flash drive that uses a FAT32 partition.  GPT and FAT32 aren't "opposite".  And you can absolutely use a GPT-initialized disk to boot in UEFI mode from USB devices.  I do it all the time, and in fact UEFI is explicitly intended to boot from GPT devices.  It also supports booting from MBR-initialized devices for backward compatibility, but it's fine with GPT.

Spanning WIMs can be a problem because the Windows Setup interface won't allow you to select images that reside in a spanned WIM, so if you use a spanned WIM you'd need to apply the image to the disk manually using a tool like DISM -- but most people don't know how to do that.  If I have a WIM that's larger than 4GB, I use Rufus to create a specially prepared flash drive that uses an NTFS partition for the main data but also contains a small FAT partition that stores a UEFI NTFS driver.  That way, when I boot the system in UEFI mode, it initially boots from the FAT partition, loads the UEFI NTFS driver, and then turns around and boots from whatever is on the NTFS partition.  It works brilliantly.  The only catch is that you have to disable Secure Boot because the bootloader for the NTFS driver is provided under an open source license and Microsoft therefore won't sign the bootloader so that it's trusted under Secure Boot.  But you can re-enable Secure Boot after you've installed whatever OS you're installing.

In order to get UEFI to work you can't use GPT - you must use fat32 during creation of the bootable usb.  Use diskpart to clean, partition, and format the stick using fat32 as the filesystem. Span the .wim's if they are too large.  I believe that GPT used to work but recent firmware updates changed this - I'm not certain.  What I can say is that I had a bootable uefi system that was GPT in order to support large files but this no longer enumerates on Dell systems -  However, it still works on HP's.  I suspect a BIOS update or an Intel firmware update made this change - and for the worse.

In order to get UEFI to work you can't use GPT - you must use fat32 during creation of the bootable usb.  Use diskpart to clean, partition, and format the stick using fat32 as the filesystem. Span the .wim's if they are too large.  I believe that GPT used to work but recent firmware updates changed this - I'm not certain.  What I can say is that I had a bootable uefi system that was GPT in order to support large files but this no longer enumerates on Dell systems -  However, it still works on HP's.  I suspect a BIOS update or an Intel firmware update made this change - and for the worse.

I should have elaborated more - It is possible to have a bootable UEFI stick with GPT - but I'm having problems with Dell's that have received recent BIOS updates listing the file system.  These enumerate with "PMAP" when you do an f12 at boot.  I think the update made a change so that it requires you to use fat32 so that it can read the efi - if the partition where the efi is located is on gpt it's not reading like it used to.  Like I said - used to work and now suddenly doesn't after firmware updates but still works on other systems...  This was on a stick that was created by acronis imaging - I made a backup of the stick, then used diskpart to clean, partition, and format with fat32.  After marking the partition as active and copying the files back down (Files over 4gb need to be spanned or enumerated on a separate partition) it worked as it used to.  When partitioning you can probably mark the system partition as fat32 and then just save your images or whatever to another partition.  You would need to use DISM if you want windows install files over 4gb on the primary partition by spanning them - I think the original post was about Linux or something... I would probably just boot a live stick and install ubuntu over the internet.