Uefi doesn't see flash drive

[Woosos]

Hello guys!

I have a question. I recently made a tiny OS for UEFI on c++, and my brother gave me a Samsung laptop (with UEFI), and it was made in 2015. But I don't know how to boot my OS, I've already tried.img, I even just put files on a flash drive, but it doesn't see my flash drive. Should I create .iso or something else? csm and secure boot are disabled.

thanks.

[icr09]

Just a heads-up before I begin my explanation: if your kernel is legacy/MBR, it won't work if your computer doesn't support it.


Follow exactly what I say here, provided your system is functional in QEMU.


minimum requirements for a UEFI loader (the bare minimum I managed to get working)

Your kernel must be generated as a file named:

bootx64.efi or bootx32.efi. I assume that if it is on an EFI system, it is 64-bit, but this explanation applies to both. Your flash drive must be formatted as FAT32; then, open the flash drive and create the following folders:


mkdir -p EFI/BOOT/bootx64.efi

Conversely, if this file directory does not exist or is not in FAT32 format, it will be ignored; I recommend using a flash drive configured via Rufus.

as this is the minimum required for the UEFI to support a charger.




ex: (your media on FAT32)

└── EFI

└── BOOT

└── BOOTX64.EFI (or corresponding to the architecture)

If you’d like some help, reach out to me on Discord—my username is 'icr09'. I’ll be keeping an eye out for friend requests.

[BenLunt]

I ran into something similar a little while ago.

How to get my code to boot on real hardware using UEFI?

There are a few specifics that you must conform to.
1) Your GPT must occupy the whole thumb drive.
2) You must have a valid FAT file system installed.
3) The name of the file must be correct depending on the platform.
4) the file itself must be built to boot via EFI.

Ben

[Octocontrabass]

1) Your GPT must occupy the whole thumb drive.

Windows uses MBR-partitioned USB flash drives. Firmware vendors usually only care about Windows, so I would avoid GPT since it may not work on some PCs. Some firmware is known to reject unpartitioned USB drives, so there is precedent.

2) You must have a valid FAT file system installed.

Windows uses FAT32. Some firmware is known to reject FAT16 and FAT12.

[icr09]

1) Your GPT must occupy the whole thumb drive.

Windows uses MBR-partitioned USB flash drives. Firmware vendors usually only care about Windows, so I would avoid GPT since it may not work on some PCs. Some firmware is known to reject unpartitioned USB drives, so there is precedent.

2) You must have a valid FAT file system installed.

Windows uses FAT32. Some firmware is known to reject FAT16 and FAT12.

Well, as far as I know and based on what I did I just used Rufus to set up the structure and then placed the bootloader inside it.