DxeFrb

Field	Value
Index	262
Module	DxeFrb
File	DxeFrb.efi
PE format	PE32+
Size (hex)	2364h
Size (bytes)	9,060
Subsystem	EFI Boot Service (000Bh)
Sections	5 (.text, .rdata, .data, section_3, .xdata)
Phase	DXE
Source	Lenovo HR650X UEFI BIOS
Build	HR6N0XMLK, DEBUG_VS2015, X64

Overview

This driver manages the hardware FRB2 (Fault Resilient Boot Phase 2) watchdog timer and the OS boot watchdog timer through the WCHG (Watchdog Chip) accessed via CMOS I/O ports 0x70/0x71. During boot phases where the system could hang (option ROM init, password prompt, setup), FRB2 is temporarily disabled and re-enabled after each critical phase completes. The OS Boot WDT supervises the OS boot process and is disabled before entering the UEFI Shell.

Key Functions

GetDebugProtocol / DebugPrint -- acquire WCHG debug protocol and print debug messages
Frb2Init -- initialize the FRB2 watchdog timer
Frb2Disable -- disable FRB2 during critical boot phases (option ROM, setup)
Frb2ReEnable -- re-enable FRB2 after a critical phase completes
OsWdtArm / OsWdtDisarm -- arm and disarm the OS boot watchdog (default 60s timeout)
OsWdtStatus -- check current OS boot watchdog state
WchgTimerState management (3 timers, 6 bytes each)

Dependencies

EFI_WATCHDOG_TIMER_ARCH_PROTOCOL
CMOS I/O ports 0x70/0x71 (WCHG watchdog chip)
UEFI Boot Services
WCHG Debug Protocol
Event notification (ReadyToBoot, VirtualAddressChange)

Platform

Intel/AMD64 UEFI, Lenovo HR650X BIOS