BIOS: Difference between revisions
→BIOS in Protected Mode: Really, dont.
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If you must use Real Mode BIOS functions after the CPU has been switched into Protected Mode, then see [[Virtual 8086 Mode]],
or perhaps exit Protected Mode, and momentarily return to [[Real Mode]]. Both methods have
* BIOS calls may use interrupts, which means that you need to forward IRQs or map the PIC back to its original configuration.
* BIOS calls may access devices that you have already configured - notably the PIT and PIC
* BIOS calls can enter protected mode on their own to access MMIO registers, which is beyond the limits of virtual 8086 mode.
* In real mode, you have no way of managing interrupts and your drivers may get stuck for interrupts being lost.
* In real mode, you have no control over time, performance and security guarantees.
The only device that's mostly exempt from these problems is the Video BIOS, which is not generally bundled with your motherboard and therefore can't rely on BIOS services either. Most current OSes - commercial and hobbyist alike - use a v8086 monitor or emulator to support graphics devices without a native driver so many BIOSes have been tested against such a set-up.
==Additional Information from the BIOS==
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