![]() The kernel is a valid EFI executable which can be loaded directly from the UEFI firmware with efibootmgr, or another bootloader. Encryption mentioned in file system support is filesystem-level encryption, it has no bearing on block-level encryption.This protocol may however cause issues with certain BIOS implementations see rodsbooks for details. GPT on BIOS systems is possible, using either "hybrid booting" with Hybrid MBR, or the new GPT-only protocol. As GPT is part of the UEFI specification, all UEFI boot loaders support GPT disks.If Secure Boot is enabled, the boot process will verify authenticity of the EFI binary by signature. It could be some other EFI application such as the UEFI shell or a boot manager like systemd-boot or rEFInd.This could be a boot loader or the Arch kernel itself using EFISTUB.This is how UEFI bootable removable media work. In this case the firmware looks for an EFI system partition on that disk and tries to find an EFI application in the fallback boot path \EFI\BOOT\BOOT圆4.EFI ( BOOTIA32.EFI on systems with a IA32 (32-bit) UEFI). Firmware reads the boot entries in the NVRAM to determine which EFI application to launch and from where (e.g.After POST, UEFI initializes the hardware required for booting (disk, keyboard controllers etc.).The boot loader then loads an operating system by either chain-loading or directly loading the operating system kernel.for GRUB on a GPT partitioned disk-a GRUB-specific BIOS boot partition (it is used in place of the post-MBR gap that does not exist in GPT).a partition's or a partitionless disk's volume boot record (VBR),.the so called post-MBR gap (only on a MBR partition table), The boot loader's first stage in the MBR boot code then launches its second stage code (if any) from either:. ![]() BIOS launches the first 440 bytes ( the Master Boot Record bootstrap code area) of the first disk in the BIOS disk order.After POST, BIOS initializes the hardware required for booting (disk, keyboard controllers etc.).System switched on, the power-on self-test (POST) is executed.Note: Intel is phasing out support for CSM, relying on the feature may not be feasible in the future. If a CSM boot entry is chosen to be booted from, the UEFI's CSM will attempt to boot from the drive's MBR bootstrap code. If CSM is enabled in the UEFI, the UEFI will generate CSM boot entries for all drives. The UEFI specification has support for legacy BIOS booting with its Compatibility Support Module (CSM). The applications can be launched by adding a boot entry to the NVRAM or from the UEFI shell. Each vendor can store its files in the EFI system partition under the /EFI/ vendor_name directory. These applications are usually stored as files in the EFI system partition. boot loaders, boot managers, UEFI shell, etc. UEFI implementations also support ISO-9660 for optical discs. ![]() The UEFI specification mandates support for the FAT12, FAT16, and FAT32 file systems (see UEFI specification version 2.9, section 13.3.1.1), but any conformant vendor can optionally add support for additional file systems for example, HFS+ or APFS in some Apple's firmwares. UEFI does not launch any boot code from the Master Boot Record (MBR) whether it exists or not, instead booting relies on boot entries in the NVRAM. The Unified Extensible Firmware Interface has support for reading both the partition table as well as file systems. Originally created for the IBM PC to handle hardware initialization and the boot process, it has been replaced progressively since 2010 by the UEFI which does not suffer from the same technical limitations. Tip: The words BIOS and (U)EFI are often used instead of firmware BIOSĪ BIOS or Basic Input-Output System is in most cases stored in a flash memory in the motherboard itself and independent of the system storage.
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