CsmBlockIo, 0158, 14016 bytes, DXE

UEFI CSM Compatibility Support Module Block I/O driver. Bridges UEFI Block I/O protocols to legacy INT 13h disk services for CSM booting (e.g., booting legacy OS from UEFI). Handles CHS, LBA, and extended INT 13h operations with retry logic, removable media detection, and BBS (BIOS Boot Specification) table management.

Key Functions: CsmBlockIoEntryPoint (installs DiskInfo, LegacyBiosExt, LegacyBios protocols), CsmBlockIoInitDevice (per-device INT13 setup), Int13ChsReadWrite (CHS mode 0x02/0x03), Int13ExtendedRead (LBA/EDD mode 0x42), Int13IdentifyDevice, Int13GetDriveParameters (INT13 fn 0x48), BbsDeviceTypeBuilder.

Protocols/Dependencies: EFI_BLOCK_IO_PROTOCOL, EFI_DISK_IO_PROTOCOL, EFI_LEGACY_BIOS_PROTOCOL, EFI_LEGACY_INTERRUPT_PROTOCOL, EFI_LEGACY_8259_PROTOCOL, EFI_LEGACY_REGION_PROTOCOL, EFI_LEGACY_MBR_PROTOCOL.

Platform: AmiModulePkg/CSM/CsmBlockIo, VS2015 X64 DEBUG.