Revision as of 10:27, 25 August 2025 edit Citation bot (talk \| contribs) Bots 5,870,246 edits Add: date, authors 1-1. Removed URL that duplicated identifier. \| Use this bot. Report bugs. \| Suggested by Headbomb \| Linked from Wikipedia:WikiProject_Academic_Journals/Journals_cited_by_Wikipedia/Sandbox \| #UCB_webform_linked 306/1032 ← Previous edit		Latest revision as of 15:56, 25 August 2025 edit undo 103.40.79.10 (talk) →Bootloader stage: The MBR boot sector (MBR boot code) is only used on x86 BIOS systems. However, the MBR partition table can be used on modern UEFI PCs, as well as non-x86 embedded devices (while the boot loader is not MBR boot sector). Tags: Mobile edit Mobile web edit
Line 21: == Bootloader stage == ~~The~~In [[IBM PC compatible]]s, the first stage bootloader, which is a part of the MBR, is a 512-byte image containing the vendor-specific program code and a partition table.{{Sfn\|M. Tim Jones\|2006\|loc=, "Stage 1 boot loader"}} As mentioned earlier in the introduction part, the first stage bootloader will find and load the second stage bootloader.{{Sfn\|M. Tim Jones\|2006\|loc=, "Stage 1 boot loader"}} It does this by searching in the partition table for an active partition.{{Sfn\|M. Tim Jones\|2006\|loc=, "Stage 1 boot loader"}} After finding an active partition, first stage bootloader will keep scanning the remaining partitions in the table to ensure that they're all inactive.{{Sfn\|M. Tim Jones\|2006\|loc=, "Stage 1 boot loader"}} After this step, the active partition's boot record is read into RAM and executed as the second stage bootloader.{{Sfn\|M. Tim Jones\|2006\|loc=, "Stage 1 boot loader"}} The job of the second stage bootloader is to load the Linux kernel image into memory, and optional initial RAM disk.{{Sfn\|M. Tim Jones\|2006\|loc=, "Stage 2 boot loader"}} Kernel image isn't an executable kernel, but a [[Vmlinux\|"compressed file" of the kernel]] instead, compressed into either [[Vmlinux\|zImage or bzImage]] formats with [[zlib]].{{Sfn\|M. Tim Jones\|2006\|loc=, "Kernel"}} In x86 PC, first- and second-stage bootloaders are combined into the [[GNU GRUB\|GRand Unified Bootloader]] (GRUB), and formerly Linux Loader ([[LILO (bootloader)\|LILO]]).{{Sfn\|M. Tim Jones\|2006\|loc=, "Stage 2 boot loader"}} [[GRUB 2]], which is now used, differs from GRUB 1 by being capable of automatic detection of various operating systems and automatic configuration. The stage1 is loaded and executed either by the [[BIOS]] from the [[Master boot record]] (MBR). The intermediate stage loader (stage1.5, usually core.img) is loaded and executed by the stage1 loader. The second-stage loader (stage2, the /boot/grub/ files) is loaded by the stage1.5 and displays the GRUB startup menu that allows the user to choose an operating system or examine and edit startup parameters. After a menu entry is chosen and optional parameters are given, GRUB loads the linux kernel into memory and passes control to it. GRUB 2 is also capable of chain-loading of another bootloader. In [[UEFI]] systems, the stage1 and stage1.5 usually are the same UEFI application file (such as grubx64.efi for [[x64]] UEFI systems).

Booting process of Linux: Difference between revisions