Writing Custom Kernel Drivers

RTKernel-32 is delivered with drivers suitable for PC compatible or similar systems running under RTTarget-32. Nevertheless, thanks to its driver structure, it is easily possible to run RTKernel-32 on other systems. However, modifications to the existing drivers or new drivers might be required.

The documentation for all drivers in section RTKernel-32 Drivers details each driver's hard- and software requirements. If you cannot meet the requirements for a complete set of drivers, one or more drivers must be replaced. To accomplish this, the recommended method is to copy the source files of the driver most closely matching the desired functionality and then modifying the copy as required. Each driver's interface is documented in the respective driver header file. For example, the system driver's functionality is detailed in file Rtksys.h.

The following table summarizes the source files required to build the drivers delivered with RTKernel-32. All driver source files are located in directory Driver\Rtk32:

Type	Name	Source Files	Comments
System	SYSSTD	SYSSTD.C HALT386.ASM	No TLS support. Relies only on C/C++ RTL
System	SYSRT32	SYSRTT32.C HALT386.ASM FSSEG.ASM HALT386.ASM RTTDBG.ASM SYSRTMP.C	Requires RTTarget-32. TLS, Win32, and MP support limits number of tasks to 8192.
Interrupt	IRQRT32	IRQCALL.OBJ IRQRTT.C I8259.ASM DUMISRS.ASM IFLAG.ASM	Support for Preemptions. Requires RTTarget-32 and 8259A interrupt controller(s). Supports 16 IRQs.
Clock	CLKPC	CLKHRTPC.ASM	Requires 8253 timer. Incompatible with drivers CLKPC and HRTPC.
Clock	CLKHRTPC	CLKHRTPC.ASM	Requires 8253 timer. Combined Clock and high-resolution timer driver. Incompatible with drivers CLKPC and HRTPC.
Clock	CLKAPIC	CLKAPIC.C	Requires Pentium and APIC.
Clock	CLKVMF	CLKVMF.C	Requires RTVmf-32.
Clock	CLKRTH	CLKRTH.C	Requires RTRth-32.
Highres. Timer	HRTNULL	HRTNULL.ASM	Does not implement any timer services.
Highres. Timer	HRTPC	CLKHRTPC.ASM	Requires 8253 timer. Incompatible with drivers CLKHRTPC and CLKPC.
Highres. Timer	CLKHRTPC	CLKHRTPC.ASM	Requires 8253 timer. Combined Clock and high-resolution timer driver. Incompatible with drivers CLKPC and HRTPC.
Highres. Timer	HRTPENT	HRTPENT.ASM	Requires Pentium or higher. Must be calibrated at run-time.
Highres. Timer	HRTSC520	HRTSC20.ASM	Requires AMD SC520 CPU.
Highres. Timer	HRTPM	HRTPM.C PMTASM.ASM	Requires ACPI BIOS and Pentium or higher CPU.
Highres. Timer	HRTHPET	HRTHPET.C HPETASM.ASM	Requires ACPI BIOS and Pentium or higher CPU.
Highres. Timer	HRTVMF	HRTVMF.C	Requires RTVmf-32
Floating Point	FLTNULL	FLTNULL.ASM	Does not swap floating point context.
Floating Point	FLT387	FLT387.ASM	Requires 387 or 100% compatible emulator.
Floating Point	FLTPII	FLTPII.ASM	Requires 387 or higher CPU.
Floating Point	FLTEMUMT	FLTEMUMT.ASM	Requires 387 or higher or reentrant emulator.
Memory	MEMCHEAP	CHEAP.C	Uses malloc/free. Does not support RTKernel-32 calls before function main has been called.
Memory	MEMSTH	STHEAP.C STHDATA.C STHCALL.C	Static heap in data segment. Supports additional function MEMSTHeapInfo.
Memory	MEMW32	MEMW32.C	Uses Win32 Heaps.
Memory	MEMSTCH	STHEAP.C STHDATA.C STCHEAP.C	Combined MEMCHEAP and MEMSTH.
Source Code	SRCNULL	SRCNULL.C	Does not implement source code position information.
Source Code	SRCTDS	READTDS.C TDSGETP.C	Requires read-only access to a file.
Source Code	SRCMAP	READMAP.C TDSGETP.C	Requires read-only access to a file.

Subsequently, the new driver should be linked after library Rtk32[s].lib or Rtk32mp[s].lib and before any driver libraries delivered with RTKernel-32.