7

When the kernel been loaded into the memory, can it still can use BIOS interrupts? Such as 

mov AX,0E820h
int 15h

or something.

1201ProgramAlarm
  • 32,384
  • 7
  • 42
  • 56
KME
  • 91
  • 2
  • 1
    A UEFI machine can support BIOS interrupts if it still supports the compatibility support module (CSM) that provides legacy BIOS interface. Some UEFI machines no longer ship with CSM support so it depends. – Michael Petch Feb 08 '20 at 03:49
  • 1
    I *think* only when booting a legacy 512-byte MBR boot sector (via the CSM), not after booting a 32 or 64-bit UEFI application. – Peter Cordes Feb 08 '20 at 06:01

1 Answers1

11

A UEFI program (or an OS loaded from one) cannot use legacy interrupts; it has to use the UEFI API.

If a UEFI BIOS includes the compatibility support module (CSM), then it supports legacy interrupts when booting a legacy boot sector.

To obtain the e820 memory map, call the UEFI boot services function GetMemoryMap.

prl
  • 11,716
  • 2
  • 13
  • 31