Yeah it is complicated , when you look at a freshly written USB stick with gnome disks there is a box you can tick that says Legacy BIOS bootable , I'm not sure if gnome disks is doing as described below with the "bios_grub" flag as the link talks about a hardrive so i'm not sure if it would apply to a USB stick?
>BIOS-Boot or EFI partition (required on GPT disks)
>The BIOS-boot partition contains GRUB 2's core. It is necessary if you install Ubuntu on a GPT >disk, and if the firmware (BIOS) is set up in Legacy (not EFI) mode. It must be located at the >start of a GPT disk, and have a "bios_grub" flag.
Yeah it is complicated , when you look at a freshly written USB stick with gnome disks there is a box you can tick that says Legacy BIOS bootable , I'm not sure if gnome disks is doing as described below with the "bios_grub" flag as the link talks about a hardrive so i'm not sure if it would apply to a USB stick?
https:/ /help.ubuntu. com/community/ DiskSpace
>BIOS-Boot or EFI partition (required on GPT disks)
>The BIOS-boot partition contains GRUB 2's core. It is necessary if you install Ubuntu on a GPT >disk, and if the firmware (BIOS) is set up in Legacy (not EFI) mode. It must be located at the >start of a GPT disk, and have a "bios_grub" flag.