1 /** @file 2 This code fills in BDA (0x400) and EBDA (pointed to by 0x4xx) 3 information. There is support for doing initializeation before 4 Legacy16 is loaded and before a legacy boot is attempted. 5 6 Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR> 7 8 This program and the accompanying materials 9 are licensed and made available under the terms and conditions 10 of the BSD License which accompanies this distribution. The 11 full text of the license may be found at 12 http://opensource.org/licenses/bsd-license.php 13 14 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 15 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 16 17 **/ 18 19 #include "LegacyBiosInterface.h" 20 21 /** 22 Fill in the standard BDA and EBDA stuff before Legacy16 load 23 24 @param Private Legacy BIOS Instance data 25 26 @retval EFI_SUCCESS It should always work. 27 28 **/ 29 EFI_STATUS 30 LegacyBiosInitBda ( 31 IN LEGACY_BIOS_INSTANCE *Private 32 ) 33 { 34 BDA_STRUC *Bda; 35 UINT8 *Ebda; 36 37 Bda = (BDA_STRUC *) ((UINTN) 0x400); 38 Ebda = (UINT8 *) ((UINTN) 0x9fc00); 39 40 ZeroMem (Bda, 0x100); 41 ZeroMem (Ebda, 0x400); 42 // 43 // 640k-1k for EBDA 44 // 45 Bda->MemSize = 0x27f; 46 Bda->KeyHead = 0x1e; 47 Bda->KeyTail = 0x1e; 48 Bda->FloppyData = 0x00; 49 Bda->FloppyTimeout = 0xff; 50 51 Bda->KeyStart = 0x001E; 52 Bda->KeyEnd = 0x003E; 53 Bda->KeyboardStatus = 0x10; 54 Bda->Ebda = 0x9fc0; 55 56 // 57 // Move LPT time out here and zero out LPT4 since some SCSI OPROMS 58 // use this as scratch pad (LPT4 is Reserved) 59 // 60 Bda->Lpt1_2Timeout = 0x1414; 61 Bda->Lpt3_4Timeout = 0x1400; 62 63 *Ebda = 0x01; 64 65 return EFI_SUCCESS; 66 } 67
