Why can read the hard disk drives system BIOS to boot load the MBR? Under the master can help to reassure, thank you!

CodePudding user response:

. Read the master boot record (MBR), when the BIOS checks to the hardware with normal after the match the Settings in the CMOS, detection in CMOS to boot device set in order the boot device available, the BIOS will boot device corresponding the first sector (that is, the MBR sector) read into memory address is 0000:7 c00h place,

CodePudding user response:

reference 1st floor wisewoman response:

reads the master boot record (MBR), when the BIOS checks to the hardware with normal after the match the Settings in the CMOS, according to the CMOS to boot device Settings in order to detect available boot device, the BIOS will boot device corresponding the first sector (that is, the MBR sector) read into memory address is 0000:7 c00h,

Load the MBR, that is, equipment already recognize the hard disk, why load hard disk drive?

CodePudding user response:

Operating systems do not know ah

CodePudding user response:

The bird said elder brother in the operation of the replacement hard disk type affect the boot process is is there a problem?

CodePudding user response:

General (non UEFI) system startup process is in accordance with,
The BIOS - & gt; BootLoader (GRUB, LILO, uboot, etc.) - & gt; The KERNEL - & gt; Initramfs - & gt; Rootfs, this process of
The BIOS, the BootLoader, KERNEL, relatively independent function of each part, that is to say, the same device can be used in the BIOS, if there is no support in the BootLoader code BootLoader can't use, BootLoader and the KERNEL is the same, the relationship between the KERNEL stage after the CPU is basic it is non-privileged mode system interface to run the program from the KERNEL

After completion of the BIOS self-checking read disk first sector data (including startup code and the partition table) to 0:7 c00H and jump to this address, and then by the startup code to take over the system, startup code is very small, limited functionality, usually responsible for continue to load the other boot code, parsing the partition table, looking for support to start the system partition, load the system KERNEL, according to the configuration parameter to start the system KERNEL, precompiled KERNEL of some drivers into the KERNEL, so when the KERNEL initialization system, will gradually start these drivers, when the driver initialization complete, according to the device driver support for initramfs or rootfs,
If not find, will start failure,
Initramfs is to avoid too much into the kernel driver volume is too large and introduce, it will be done with some drive insmod work some preparation work in entering the rootfs