UEFI and legacy boot modes in the BIOS

The BIOS, the basic input/output system, turns into Chinese as "basic input/Output systems", a so-called "firmware" that is responsible for hardware startup and detection when booting, and as an intermediary role in operating system-controlled hardware.

In the BIOS setup, there are two ways to get him to boot into the system, respectively, for UEFI and Legacey

where the BIOS (Legacy) is traditional, and uefi (Unified extensible Firmware Interface) is the extensible Firmware interface that was developed later, the maximum number of uefi differences compared to the Legacy BIOS is:
1. The code 99% is completed by C language;
2. A new way to change the previous interrupt, hardware port operation, and adopt Driver/protocol;
3. X86 Real mode will not be supported, and the direct use of flat mode (that is, no DOS, now some EFI or UEFI can be used because it is compatible, but in fact this part is not the definition of UEFI);
4. The output is no longer a simple binary code, instead removable binary Drivers;
5. OS boot no longer calls Int19, but uses protocol/device Path directly;
6. For third-party development, the former basically does not, unless involved in the design of the BIOS, but also by the size of the ROM limit, the latter is much more convenient.

7. Make up for the lack of BIOS support for new hardware

Look at their differences from the start-up process:

As we all know, the WIN8 system has a considerable increase in boot speed relative to the Win7 system, because the WIN8 system has added technologies such as boot booting and application pre-caching to improve system performance and optimize hardware. With the UEFI BIOS booting, you can make the platform more intelligent and boot faster. Let's look at the difference between their booting into the system:

This is the traditional legacy running process:

This is the UEFI run process:

Compared to the traditional BIOS boot mode, the UEFI BIOS reduces the steps of the BIOS self-test and saves a lot of time, thus speeding up the platform.

The hard disk partition format for each of the two modes

In the legacy boot mode, the hard disk partition format should be MBR format;

In Uefi boot mode, the hard disk partition format should be in the GUID (GPT) format.

UEFI and legacy boot modes in the BIOS