LegacyInterrupt

Overview

LegacyInterrupt is a DXE driver for Intel Purley/Lewisburg PCH platforms that manages legacy PCI interrupt routing. It installs the EFI_LEGACY_INTERRUPT_PROTOCOL to provide platform-level control over PCI interrupt line programming, legacy interrupt vector management, and PCH LPC register access. The driver handles interrupt status queries, vector read/write operations, and PCH stepping detection for Lewisburg PCH.

Key Functions

• LegacyInterruptInstall() -- Installs the legacy interrupt protocol on a new handle
• LegacyInterruptGetStatus() -- Returns current legacy interrupt status
• LegacyInterruptGetVector() -- Retrieves the interrupt vector number
• LegacyInterruptReadVector() -- Reads an interrupt vector register
• LegacyInterruptWriteVector() -- Writes a value to an interrupt vector register
• LibConstructor() -- Library constructor that initializes UEFI boot services and system table
• PchGetStepping() -- Detects the PCH stepping version
• LpcWriteRegister() -- Writes to LPC bridge configuration registers

Dependencies

• gEfiLegacyInterruptProtocolGuid -- EFI Legacy Interrupt Protocol
• gMmPciUsraProtocolGuid -- MM PCI USRA Protocol (from CpRcPkg/DxeMmPciBaseLib)
• gEfiPcdProtocolGuid -- PCD Protocol
• gEfiHobListGuid -- HOB List GUID
• gEfiDxeServicesTableGuid -- DXE Services Table

Platform

• CPU: Intel Purley (Xeon Scalable)
• PCH: Lewisburg (LBG)
• Architecture: x86-64 (PE32+)
• Subsystem: EFI_BOOT_SERVICE_DRIVER (0x0B)
• Toolchain: VS2015 (DEBUG build)
• BIOS: HR650X (HR6N0XMLK)