Appendix B. Linux and the BIOS

Parts of the x86 kernel, such as the video frame buffer driver (vesafb) and Advanced Power Management (APM), explicitly use BIOS services to accomplish certain functions. Other sections of the kernel, such as the serial driver, implicitly depend on the BIOS to initialize I/O base addresses and interrupt levels. Real mode kernel code makes extensive use of BIOS calls during boot to perform tasks such as assembling the system memory map.[1] Because some device drivers depend directly or indirectly on the BIOS, let’s learn how to interact with it.

Real Mode Calls

Many parts of the kernel glean information from the BIOS in real mode and use the collected information during normal operation in protected mode.

The steps ...

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