reactos/boot/freeldr/freeldr/disk/ramdisk.c

   1 /*
   2  * PROJECT:         ReactOS Boot Loader
   3  * LICENSE:         GPL - See COPYING in the top level directory
   4  * FILE:            boot/freeldr/arch/i386/ramdisk.c
   5  * PURPOSE:         Implements routines to support booting from a RAM Disk
   6  * PROGRAMMERS:     alex@winsiderss.com
   7  */
   8
   9 /* INCLUDES *******************************************************************/
  10
  11 #include <freeldr.h>
  12 #define NDEBUG
  13 #include <debug.h>
  14
  15 /* GLOBALS ********************************************************************/
  16
  17 PVOID gRamDiskBase;
  18 ULONG gRamDiskSize;
  19 extern BOOLEAN gCacheEnabled;
  20
  21 /* FUNCTIONS ******************************************************************/
  22
  23 FORCEINLINE
  24 PVOID
  25 RamDiskGetDataAtOffset(IN PVOID Offset)
  26 {
  27     //
  28     // Return data from our RAM Disk
  29     //
  30     assert(((ULONG_PTR)gRamDiskBase + (ULONG_PTR)Offset) <
  31            ((ULONG_PTR)gRamDiskBase + (ULONG_PTR)gRamDiskSize));
  32     return (PVOID)((ULONG_PTR)gRamDiskBase + (ULONG_PTR)(Offset));
  33 }
  34
  35 ULONG
  36 RamDiskGetCacheableBlockCount(IN ULONG Reserved)
  37 {
  38     //
  39     // Allow 32KB transfers (64 sectors), emulating BIOS LBA
  40     //
  41     return 64;
  42 }
  43
  44 BOOLEAN
  45 RamDiskGetDriveGeometry(IN ULONG Reserved,
  46                         OUT PGEOMETRY Geometry)
  47 {
  48     //
  49     // Should never be called when the caller expects valid Geometry!
  50     //
  51     return TRUE;
  52 }
  53
  54 BOOLEAN
  55 RamDiskReadLogicalSectors(IN ULONG Reserved,
  56                           IN ULONGLONG SectorNumber,
  57                           IN ULONG SectorCount,
  58                           IN PVOID Buffer)
  59 {
  60     PVOID StartAddress;
  61     ULONG Length;
  62
  63     //
  64     // Get actual pointers and lengths
  65     //
  66     StartAddress = (PVOID)((ULONG)SectorNumber * 512);
  67     Length = SectorCount * 512;
  68
  69     //
  70     // Don't allow reads past our image
  71     //
  72     if (((ULONG_PTR)StartAddress + Length) > gRamDiskSize) return FALSE;
  73
  74     //
  75     // Do the read
  76     //
  77     RtlCopyMemory(Buffer, RamDiskGetDataAtOffset(StartAddress), Length);
  78     return TRUE;
  79 }
  80
  81 VOID
  82 NTAPI
  83 RamDiskCheckForVirtualFile(VOID)
  84 {
  85     PFILE RamFile;
  86     ULONG TotalRead, ChunkSize;
  87
  88     //
  89     // Try opening the ramdisk file (this assumes the boot volume was opened)
  90     //
  91     RamFile = FsOpenFile("reactos.img");
  92     if (RamFile)
  93     {
  94         //
  95         // Get the file size
  96         //
  97         gRamDiskSize = FsGetFileSize(RamFile);
  98         TuiPrintf("Found virtual ramdisk (%dKB)\n", gRamDiskSize / 1024);
  99         if (!gRamDiskSize) return;
 100
 101         //
 102         // Allocate memory for it
 103         //
 104         ChunkSize = 8 * 1024 * 1024;
 105         gRamDiskBase = MmAllocateMemory(gRamDiskSize);
 106         if (!gRamDiskBase) return;
 107
 108         //
 109         // Read it in chunks
 110         //
 111         TuiPrintf("Loading ramdisk @ 0x%x...", gRamDiskBase);
 112         for (TotalRead = 0; TotalRead < gRamDiskSize; TotalRead += ChunkSize)
 113         {
 114             //
 115             // Check if we're at the last chunk
 116             //
 117             if ((gRamDiskSize - TotalRead) < ChunkSize)
 118             {
 119                 //
 120                 // Only need the actual data required
 121                 //
 122                 ChunkSize = gRamDiskSize - TotalRead;
 123             }
 124
 125             //
 126             // Copy the contents
 127             //
 128             TuiPrintf(".");
 129             if (!FsReadFile(RamFile,
 130                             ChunkSize,
 131                             NULL,
 132                             (PVOID)((ULONG_PTR)gRamDiskBase + TotalRead)))
 133             {
 134                 //
 135                 // Fail
 136                 //
 137                 TuiPrintf("Failed to read ramdisk\n");
 138             }
 139         }
 140         TuiPrintf("\n");
 141     }
 142 }
 143
 144 VOID
 145 NTAPI
 146 RamDiskSwitchFromBios(VOID)
 147 {
 148     //
 149     // Check if we have a ramdisk, in which case we need to switch routines
 150     //
 151     if (gRamDiskBase)
 152     {
 153         //
 154         // Don't use the BIOS for reads anymore
 155         //
 156         MachVtbl.DiskReadLogicalSectors = RamDiskReadLogicalSectors;
 157         MachVtbl.DiskGetDriveGeometry = RamDiskGetDriveGeometry;
 158         MachVtbl.DiskGetCacheableBlockCount = RamDiskGetCacheableBlockCount;
 159
 160         //
 161         // Also disable cached FAT reads
 162         //
 163         gCacheEnabled = FALSE;
 164     }
 165 }
 166
 167 VOID
 168 NTAPI
 169 RamDiskInit(IN PCHAR CmdLine)
 170 {
 171     //
 172     // Get RAM disk parameters
 173     //
 174     gRamDiskBase = (PVOID)atoi(strstr(CmdLine, "rdbase="));
 175     gRamDiskSize = atoi(strstr(CmdLine, "rdsize="));
 176 }