The
bioscall() function switches the processor into real mode, calls the BIOS interrupt numbered
function, and returns to protected mode.
This function is intended to be called during the initial system bootstrap when necessary to probe devices or pseudo-devices.
The register values specified by
*regs (with one exception) are installed before the BIOS interrupt is called. The processor flags are handled specially. Only the following flags are passed to the BIOS from the registers in
regs (the remainder come from the processor's flags register at the time of the call):
PSL_C,
PSL_PF,
PSL_AF,
PSL_Z,
PSL_N,
PSL_D,
PSL_V.
The
bioscallregs structure is defined to contain structures for each register, to allow access to 32-, 16- or 8-bit wide sections of the registers. Definitions are provided which simplify access to the union members.