See also: Kernel Index, Arch, CPU
This directory defines architecture-neutral operation tables and binds them to architecture-specific implementations using a function-pointer struct pattern.
Operation Tables
The HAL defines the following operation tables, each with a global pointer variable and arch-specific bindings:
IO Operations (hal/io.h)
g_HalIoOperations — Port I/O, interrupt control, halt, panic.
-
inb(),outb(),inw(),outw(),inl(),outl() -
EnableInterrupts(),DisableInterrupts() -
Halt(),Panic()
IRQ Operations (hal/irq.h)
g_HalIrqOperations — Interrupt request management.
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RegisterHandler(),Unmask(),Mask()
Paging Operations (hal/mem.h)
g_HalPagingOperations — Full paging abstraction.
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Page table manipulation, TLB flushing, address space switching
Scheduler Operations (hal/scheduler.h)
g_HalSchedulerOperations — Context switch interface.
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Context save/restore, process switch
Syscall Operations (hal/syscall.h)
g_HalSyscallOperations — Syscall entry point.
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Syscall handler registration and dispatch
Stack Operations (hal/stack.h)
g_HalStackOperations — Stack register access.
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GetEBP(),GetESP(), stack setup
TSS Operations (hal/tss.h)
g_HalTssOperations — Task State Segment for ring transitions.
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Kernel stack pointer update for privilege level switches
Video Operations (hal/video.h)
g_HalVideoOperations — Display output.
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PutChar(),Clear(), cursor management
Architecture Mapping
Each HAL header maps architecture-specific functions to HAL_ARCH_* macros using preprocessor conditionals:
#if defined(I686)
#include <arch/i686/cpu/stack.h>
#define HAL_ARCH_Stack_GetEBP i686_Stack_GetEBP
#endifhal.c then populates the operation structs with these macros:
const HAL_StackOperations *g_HalStackOperations = &(HAL_StackOperations){
.GetEBP = HAL_ARCH_Stack_GetEBP,
};Design Principle
Kernel code must never reference architecture-specific names directly:
// Correct: architecture-agnostic
g_HalStackOperations->GetEBP();
// Wrong: ties code to i686
i686_Stack_GetEBP();Typical Work in This Area
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Add new cross-arch operation interfaces
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Wire arch-specific functions into HAL tables
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Verify kernel modules use HAL calls consistently
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Port to new architectures (x86_64, aarch64)