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HW_Boot
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HW_boot: old plattforms and tools to boot OS's.
http://sfrias.github.io/slide
- MBR and GPT boot structure.
+ For hard disks with 512-byte sectors, the MBR partition table entries allow up to a maximum of 2 TiB
+ MBR-based partition table schemes insert the partitioning information for (usually) four "primary" partitions
in the master boot record (MBR) (which on a BIOS system is also the container for code that begins the process of booting
the system). In a GPT, the first sector of the disk is reserved for a "protective MBR" such that booting a BIOS-based computer
from a GPT disk is supported, but the bootloader and operating system must both be GPT-aware. Regardless of the sector size,
the GPT header begins on the second logical block of the device.
- GUID Partition Table (GPT) is a standard for the layout of the partition table on a physical storage device.
+ It forms a part of the Unified Extensible Firmware Interface (UEFI) standard (Unified EFI Forum proposed replacement
for the PC BIOS), it is also used on some BIOS systems because of the limitations of master boot record (MBR) partition tables,
which use 32 bits for storing logical block addresses (LBA) and size information on a traditionally 512 byte disk sector.
+ FreeBSD and most Linux distributions can boot from GPT partitions on systems with both legacy BIOS firmware interface and EFI.
+ GPT forms a subset of the UEFI specification. GPT allocates 64 bits for logical block addresses,
therefore allowing a maximum disk size of 264 sectors. For disks with 512-byte sectors, maximum size is 9.4 ZB.
If the minimum size of 16,384 bytes is allocated for the partition entry array, and the default size of 128 bytes.
+ Like modern MBRs, GPTs use logical block addressing (LBA) in place of the historical cylinder-head-sector (CHS) addressing.
The protective MBR is contained in LBA 0, the GPT header is in LBA 1, and the GPT header has a pointer to the partition table,
or Partition Entry Array, typically LBA 2. The UEFI specification[4] stipulates that a minimum of 16,384 bytes, regardless
of sector size, be allocated for the Partition Entry Array. On a disk having 512-byte sectors, a partition entry array size
of 16,384 bytes and the minimum size of 128 bytes for each partition entry, LBA 34 is the first usable sector on the disk.
+ GPT also provides redundancy, writing the GPT header and partition table both at the beginning and at the end of the disk.
Demo:
- Second Instance MBR Boot Manager:
+ Plop Boot Manager is a small program to boot different operating systems, via MBR without the help/need of a BIOS,
will be installed as primary boot manager at boot disk.
+ With help of pxelinux it's possible to start the boot manager over the network.
You can store the boot manager as option rom in your BIOS, can be used as PCI option ROM in your BIOS.
+ Programming language: Assembler. Software developer: Elmar Hanlhofer
+ Features:
# USB boot without BIOS support (UHCI, OHCI and EHCI)
# PCMCIA CardBus support to enable boot from USB PC-Cards.
# Different profiles for operating systems. Define up to 16 partitions. No extra partition for the boot manager.
# MBR partition table edit.
# Access the whole USB hard disk (up to 2TB) even when the bios has a 128 GiB limit.
# Start the network card bootrom from the boot manager to boot from the network.
+ Snapshots: https://www.plop.at/en/bootmanager/screenshots.html -> Navigate forward: donate and download.