Re: C/H/S from user space

From: Jeff V. Merkey
Date: Fri Feb 17 2006 - 16:24:00 EST


Here's the code to calculate that as well -- from NetWare -- with int 13 IOCTL calls and from within Windows 98. This code builds on the djgcc DOS
version og GNU tools.

Jeff

#if (DOS_UTIL)

#define READ_DEVICE 0x02
#define WRITE_DEVICE 0x03
#define NO_VERIFY 0x00
#define WRITE_VERIFY 0x01

// convert cylinder/head/sector addressing to LBA

ULONG CHStoLBA(ULONG disk, LONGLONG cyl, ULONG head, ULONG sector)
{
register ULONG lba;
ULONG heads = SystemDisk[disk]->TracksPerCylinder;
ULONG sectors = SystemDisk[disk]->SectorsPerTrack;

lba = cyl * (heads * sectors);
lba += (head * sectors);
lba += sector;
lba -= 1; // CHS is 1 relative so adjust LBA by subtracting 1

return lba;

}

// convert LBA to cylinder/head/sector addressing

ULONG LBAtoCHS(ULONG disk, ULONG lba, LONGLONG *cyl, ULONG *head,
ULONG *sector)
{
ULONG offset;
ULONG heads = SystemDisk[disk]->TracksPerCylinder;
ULONG sectors = SystemDisk[disk]->SectorsPerTrack;

if (!cyl || !head || !sector)
return -1;

*cyl = (lba / (heads * sectors));
offset = lba % (heads * sectors);
*head = (WORD)(offset / sectors);
*sector = (WORD)(offset % sectors) + 1; // sector addressing is
// 1 relative so add 1
return 0;
}

ULONG pReadDiskSectors(ULONG disk, ULONG StartingLBA, BYTE *Sector,
ULONG sectors, ULONG readAhead)
{
register ULONG bps, ccode, bytes = 0;
register NWDISK *NWDisk;
LONGLONG cylinder;
ULONG head, sector;
static _go32_dpmi_registers r;
#if (WINDOWS_98_UTIL)
static union REGS rl;
#endif

NWFSSet(&r, 0, sizeof(_go32_dpmi_registers));

NWDisk = SystemDisk[disk];
bps = NWDisk->BytesPerSector;

if ((sectors * bps) > IO_BLOCK_SIZE)
return bytes;

#if (WINDOWS_98_UTIL)
rl.x.ax = 0x440D; // generic IOCTL
rl.h.bh = 3; // locks levels 0, 1, 2 or 3
rl.h.bl = (0x80 | (disk & 0x7F)); // dos limit is 128 drives
rl.h.ch = 0x08; // device category
rl.h.cl = 0x4B; // lock physical volume
rl.x.dx = 0; // permissions
int86(0x21, &rl, &rl);

#endif

if (NWDisk->Int13Extensions)
{
EXT_REQUEST request;

NWFSSet(&request, 0, sizeof(EXT_REQUEST));

request.Size = sizeof(EXT_REQUEST);
request.Blocks = sectors;
request.TransferBuffer = (ULONG)(NWDisk->DataSegment << 16) & 0xFFFF0000;
request.LBA = StartingLBA;

movedata(_my_ds(),
(unsigned)&request,
NWDisk->RequestSelector,
0,
sizeof(EXT_REQUEST));

r.h.ah = 0x42;
r.h.dl = (0x80 | (disk & 0x7F));
r.x.ds = NWDisk->RequestSegment;
r.x.si = 0;
r.x.ss = r.x.sp = r.x.flags = 0;

ccode = _go32_dpmi_simulate_int(0x13, &r);
if (ccode)
goto ReadExit;

// error if carry flag is set
if (r.x.flags & 1)
{
// if the drive reported an ECC occurred, return success
if (r.h.ah == 0x11)
{
movedata(NWDisk->DataSelector,
0,
_my_ds(),
(unsigned)Sector,
(sectors * bps));

bytes = (sectors * bps);
goto ReadExit;
}
else
goto ReadExit;
}

movedata(NWDisk->DataSelector,
0,
_my_ds(),
(unsigned)Sector,
(sectors * bps));

bytes = (sectors * bps);
goto ReadExit;
}
else
{
ccode = LBAtoCHS(disk, StartingLBA, &cylinder, &head, &sector);
if (ccode)
goto ReadExit;

r.h.dh = (BYTE)head;
r.h.dl = (0x80 | (disk & 0x7F));
r.h.ch = (BYTE)(cylinder & 0xFF);
r.h.cl = (BYTE)((cylinder & 0x0300) >> 2);
r.h.cl |= (BYTE)(sector & 0x3F);
r.h.ah = READ_DEVICE;
r.h.al = (BYTE)sectors;
r.x.es = NWDisk->DataSegment;
r.x.bx = 0;
r.x.ss = r.x.sp = r.x.flags = 0;

ccode = _go32_dpmi_simulate_int(0x13, &r);
if (ccode)
goto ReadExit;

// error if carry flag is set
if (r.x.flags & 1)
{
// if the drive reported an ECC occurred, return success
if (r.h.ah == 0x11)
{
movedata(NWDisk->DataSelector,
0,
_my_ds(),
(unsigned)Sector,
(sectors * bps));

bytes = (sectors * bps);
goto ReadExit;
}
else
goto ReadExit;
}

movedata(NWDisk->DataSelector,
0,
_my_ds(),
(unsigned)Sector,
(sectors * bps));

bytes = (sectors * bps);
}

ReadExit:;
#if (WINDOWS_98_UTIL)
rl.x.ax = 0x440D; // generic IOCTL
rl.h.bl = (0x80 | (disk & 0x7F)); // dos limit is 128 drives
rl.h.ch = 0x08; // device category
rl.h.cl = 0x6B; // unlock physical volume
int86(0x21, &rl, &rl);
#endif

return bytes;

}


ULONG pWriteDiskSectors(ULONG disk, ULONG StartingLBA, BYTE *Sector,
ULONG sectors, ULONG readAhead)
{
register ULONG bps, ccode, bytes = 0;
register NWDISK *NWDisk;
LONGLONG cylinder;
ULONG head, sector;
static _go32_dpmi_registers r;
#if (WINDOWS_98_UTIL)
static union REGS rl;
#endif

NWFSSet(&r, 0, sizeof(_go32_dpmi_registers));

NWDisk = SystemDisk[disk];
bps = NWDisk->BytesPerSector;

if ((sectors * bps) > IO_BLOCK_SIZE)
return bytes;

#if (WINDOWS_98_UTIL)
rl.x.ax = 0x440D; // generic IOCTL
rl.h.bh = 3; // locks levels 0, 1, 2 or 3
rl.h.bl = (0x80 | (disk & 0x7F)); // dos limit is 128 drives
rl.h.ch = 0x08; // device category
rl.h.cl = 0x4B; // lock physical volume
rl.x.dx = 0; // permissions
int86(0x21, &rl, &rl);

#endif

if (NWDisk->Int13Extensions)
{
EXT_REQUEST request;

NWFSSet(&request, 0, sizeof(EXT_REQUEST));

request.Size = sizeof(EXT_REQUEST);
request.Blocks = sectors;
request.TransferBuffer = (ULONG)(NWDisk->DataSegment << 16) & 0xFFFF0000;
request.LBA = StartingLBA;

movedata(_my_ds(),
(unsigned)&request,
NWDisk->RequestSelector,
0,
sizeof(EXT_REQUEST));

movedata(_my_ds(),
(unsigned)Sector,
NWDisk->DataSelector,
0,
(sectors * bps));

r.h.ah = 0x43;
r.h.al = NO_VERIFY;
r.h.dl = (0x80 | (disk & 0x7F));
r.x.ds = NWDisk->RequestSegment;
r.x.si = 0;
r.x.ss = r.x.sp = r.x.flags = 0;

ccode = _go32_dpmi_simulate_int(0x13, &r);
if (ccode)
goto WriteExit;

// error if carry flag is set
if (r.x.flags & 1)
{
// if the drive reported an ECC occurred, return success
if (r.h.ah == 0x11)
{
bytes = (sectors * bps);
goto WriteExit;
}
else
goto WriteExit;
}
bytes = (sectors * bps);
goto WriteExit;
}
else
{
ccode = LBAtoCHS(disk, StartingLBA, &cylinder, &head, &sector);
if (ccode)
goto WriteExit;

movedata(_my_ds(),
(unsigned)Sector,
NWDisk->DataSelector,
0,
(sectors * bps));

r.h.dh = (BYTE)head;
r.h.dl = (0x80 | (disk & 0x7F));
r.h.ch = (BYTE)(cylinder & 0xFF);
r.h.cl = (BYTE)((cylinder & 0x0300) >> 2);
r.h.cl |= (BYTE)(sector & 0x3F);
r.h.ah = WRITE_DEVICE;
r.h.al = (BYTE)sectors;
r.x.es = NWDisk->DataSegment;
r.x.bx = 0;
r.x.ds = r.x.ss = r.x.sp = r.x.flags = 0;

ccode = _go32_dpmi_simulate_int(0x13, &r);
if (ccode)
goto WriteExit;

// error if carry flag is set
if (r.x.flags & 1)
{
// if the drive reported an ECC occurred, return success
if (r.h.ah == 0x11)
{
bytes = (sectors * bps);
goto WriteExit;
}
else
goto WriteExit;
}
bytes = (sectors * bps);
goto WriteExit;
}

WriteExit:;
#if (WINDOWS_98_UTIL)
rl.x.ax = 0x440D; // generic IOCTL
rl.h.bl = (0x80 | (disk & 0x7F)); // dos limit is 128 drives
rl.h.ch = 0x08; // device category
rl.h.cl = 0x6B; // unlock physical volume
int86(0x21, &rl, &rl);
#endif

return bytes;
}

ULONG pZeroFillDiskSectors(ULONG disk, ULONG StartingLBA, ULONG sectors,
ULONG readAhead)
{
register ULONG bps, ccode, bytes = 0;
register NWDISK *NWDisk;
LONGLONG cylinder;
ULONG head, sector;
static _go32_dpmi_registers r;
#if (WINDOWS_98_UTIL)
static union REGS rl;
#endif

NWFSSet(&r, 0, sizeof(_go32_dpmi_registers));

NWDisk = SystemDisk[disk];
bps = NWDisk->BytesPerSector;

if ((sectors * bps) > IO_BLOCK_SIZE)
return bytes;

movedata(_my_ds(),
(unsigned)ZeroBuffer,
NWDisk->DataSelector,
0,
(sectors * bps));

#if (WINDOWS_98_UTIL)
rl.x.ax = 0x440D; // generic IOCTL
rl.h.bh = 3; // locks levels 0, 1, 2 or 3
rl.h.bl = (0x80 | (disk & 0x7F)); // dos limit is 128 drives
rl.h.ch = 0x08; // device category
rl.h.cl = 0x4B; // lock physical volume
rl.x.dx = 0; // permissions
int86(0x21, &rl, &rl);

#endif

if (NWDisk->Int13Extensions)
{
EXT_REQUEST request;

NWFSSet(&request, 0, sizeof(EXT_REQUEST));

request.Size = sizeof(EXT_REQUEST);
request.Blocks = sectors;
request.TransferBuffer = (ULONG)(NWDisk->DataSegment << 16) & 0xFFFF0000;
request.LBA = StartingLBA;

movedata(_my_ds(),
(unsigned)&request,
NWDisk->RequestSelector,
0,
sizeof(EXT_REQUEST));

r.h.ah = 0x43;
r.h.al = NO_VERIFY;
r.h.dl = (0x80 | (disk & 0x7F));
r.x.ds = NWDisk->RequestSegment;
r.x.si = 0;
r.x.ss = r.x.sp = r.x.flags = 0;

ccode = _go32_dpmi_simulate_int(0x13, &r);
if (ccode)
goto FillExit;

// error if carry flag is set
if (r.x.flags & 1)
{
// if the drive reported an ECC occurred, return success
if (r.h.ah == 0x11)
{
bytes = (sectors * bps);
goto FillExit;
}
else
goto FillExit;
}
bytes = (sectors * bps);
goto FillExit;
}
else
{
ccode = LBAtoCHS(disk, StartingLBA, &cylinder, &head, &sector);
if (ccode)
goto FillExit;

r.h.dh = (BYTE)head;
r.h.dl = (0x80 | (disk & 0x7F));
r.h.ch = (BYTE)(cylinder & 0xFF);
r.h.cl = (BYTE)((cylinder & 0x0300) >> 2);
r.h.cl |= (BYTE)(sector & 0x3F);
r.h.ah = 0x03;
r.h.al = (BYTE)sectors;
r.x.es = NWDisk->DataSegment;
r.x.bx = 0;
r.x.ds = r.x.ss = r.x.sp = r.x.flags = 0;

ccode = _go32_dpmi_simulate_int(0x13, &r);
if (ccode)
goto FillExit;

// error if carry flag is set
if (r.x.flags & 1)
{
// if the drive reported an ECC occurred, return success
if (r.h.ah == 0x11)
{
bytes = (sectors * bps);
goto FillExit;
}
else
goto FillExit;
}
bytes = (sectors * bps);
goto FillExit;
}

FillExit:;
#if (WINDOWS_98_UTIL)
rl.x.ax = 0x440D; // generic IOCTL
rl.h.bl = (0x80 | (disk & 0x7F)); // dos limit is 128 drives
rl.h.ch = 0x08; // device category
rl.h.cl = 0x6B; // unlock physical volume
int86(0x21, &rl, &rl);
#endif

return bytes;

}

void ScanDiskDevices(void)
{
register ULONG j, i, retCode;
BYTE *Sector;
static union REGS r;
DRIVE_INFO dinfo;

Sector = NWFSIOAlloc(IO_BLOCK_SIZE, DISKBUF_TAG);
if (!Sector)
{
NWFSPrint("nwfs: allocation error in AddDiskDevices\n");
return;
}

for (FirstValidDisk = (ULONG)-1, j = 0; j < MAX_DOS_DISKS; j++)
{

#if (WINDOWS_98_UTIL)
r.x.ax = 0x440D; // generic IOCTL
r.h.bh = 1; // locks levels 0, 1, 2 or 3
r.h.bl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
r.h.ch = 0x08; // device category
r.h.cl = 0x4B; // lock physical volume
r.x.dx = 1; // permissions
r.h.cflag = 0x0001;

int86(0x21, &r, &r);
#endif

// test fixed disk status
r.h.ah = 0x10; // test drive status
r.h.dl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
int86(0x13, &r, &r);

// if we got the drive status, and the drive is active,
// assume the disk is valid.
if ((!r.h.cflag) && (!r.h.ah))
{
// now check if this device supports removable media. This
// would indicate this device is a CDROM drive. If we detect
// that this device supports removable meida, then do not
// add it -- it's most likely a CDROM or tape device and
// we should not add it.

// see if a change line is available for this device.
r.h.ah = 0x15; // test drive status
r.h.dl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
int86(0x13, &r, &r);

// 00-no drive, 01-diskette, 02-change line, 03-fixed disk
if (r.h.ch == 0x02)
{

#if (WINDOWS_98_UTIL)
r.x.ax = 0x440D; // generic IOCTL
r.h.bl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
r.h.ch = 0x08; // device category
r.h.cl = 0x6B; // unlock physical volume
int86(0x21, &r, &r);
#endif
continue;
}

if (!SystemDisk[j])
{
SystemDisk[j] = (NWDISK *) NWFSAlloc(sizeof(NWDISK), NWDISK_TAG);
if (!SystemDisk[j])
{
NWFSPrint("nwfs: memory allocation failure in AddDiskDevices\n");

#if (WINDOWS_98_UTIL)
r.x.ax = 0x440D; // generic IOCTL
r.h.bl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
r.h.ch = 0x08; // device category
r.h.cl = 0x6B; // unlock physical volume
int86(0x21, &r, &r);
#endif
continue;
}
NWFSSet(SystemDisk[j], 0, sizeof(NWDISK));
}

SystemDisk[j]->PhysicalDiskHandle = (void *)(0x80 | (j & 0x7F));
SystemDisk[j]->DiskNumber = j;
SystemDisk[j]->Int13Extensions = Int13ExtensionsPresent(j);

SystemDisk[j]->DataSegment =
__dpmi_allocate_dos_memory(PARAGRAPH_ALIGN(IO_BLOCK_SIZE),
&SystemDisk[j]->DataSelector);
if (SystemDisk[j]->DataSegment == (WORD) -1)
{
SystemDisk[j]->PhysicalDiskHandle = 0;
NWFSFree(SystemDisk[j]);
SystemDisk[j] = 0;

#if (WINDOWS_98_UTIL)
r.x.ax = 0x440D; // generic IOCTL
r.h.bl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
r.h.ch = 0x08; // device category
r.h.cl = 0x6B; // unlock physical volume
int86(0x21, &r, &r);
#endif
continue;
}

SystemDisk[j]->DriveInfoSegment =
__dpmi_allocate_dos_memory(PARAGRAPH_ALIGN(IO_BLOCK_SIZE),
&SystemDisk[j]->DriveInfoSelector);
if (SystemDisk[j]->DriveInfoSegment == (WORD) -1)
{
if (SystemDisk[j]->DataSelector)
__dpmi_free_dos_memory(SystemDisk[j]->DataSelector);
SystemDisk[j]->DataSelector = 0;

SystemDisk[j]->PhysicalDiskHandle = 0;
NWFSFree(SystemDisk[j]);
SystemDisk[j] = 0;

#if (WINDOWS_98_UTIL)
r.x.ax = 0x440D; // generic IOCTL
r.h.bl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
r.h.ch = 0x08; // device category
r.h.cl = 0x6B; // unlock physical volume
int86(0x21, &r, &r);
#endif
continue;
}

SystemDisk[j]->RequestSegment =
__dpmi_allocate_dos_memory(PARAGRAPH_ALIGN(sizeof(EXT_REQUEST)),
&SystemDisk[j]->RequestSelector);
if (SystemDisk[j]->RequestSegment == (WORD) -1)
{
if (SystemDisk[j]->DataSelector)
__dpmi_free_dos_memory(SystemDisk[j]->DataSelector);
SystemDisk[j]->DataSelector = 0;

if (SystemDisk[j]->DriveInfoSelector)
__dpmi_free_dos_memory(SystemDisk[j]->DriveInfoSelector);
SystemDisk[j]->DriveInfoSelector = 0;

SystemDisk[j]->PhysicalDiskHandle = 0;
NWFSFree(SystemDisk[j]);
SystemDisk[j] = 0;

#if (WINDOWS_98_UTIL)
r.x.ax = 0x440D; // generic IOCTL
r.h.bl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
r.h.ch = 0x08; // device category
r.h.cl = 0x6B; // unlock physical volume
int86(0x21, &r, &r);
#endif
continue;
}

// if int 13 extensions are present, then adjust drive geometry
// based on reported drive info.

if (SystemDisk[j]->Int13Extensions)
{
register ULONG cylinders, heads, sectors;
_go32_dpmi_registers r32;

NWFSSet(&r32, 0, sizeof(_go32_dpmi_registers));
NWFSSet(&dinfo, 0, sizeof(DRIVE_INFO));

dinfo.Size = sizeof(DRIVE_INFO);

movedata(_my_ds(), (unsigned)&dinfo,
SystemDisk[j]->DriveInfoSelector, 0,
sizeof(DRIVE_INFO));

// get int 13 extension drive info
r32.h.ah = 0x48;
r32.h.dl = (0x80 | (j & 0x7F));
r32.x.si = 0;
r32.x.ds = SystemDisk[j]->DriveInfoSegment;

_go32_dpmi_simulate_int(0x13, &r32);

movedata(SystemDisk[j]->DriveInfoSelector, 0,
_my_ds(), (unsigned)&dinfo,
sizeof(DRIVE_INFO));

// if TotalSectors is 0, then there are no drives
// attached to this controller.

if (!dinfo.TotalSectors)
{
if (SystemDisk[j]->RequestSelector)
__dpmi_free_dos_memory(SystemDisk[j]->RequestSelector);
SystemDisk[j]->RequestSelector = 0;

if (SystemDisk[j]->DataSelector)
__dpmi_free_dos_memory(SystemDisk[j]->DataSelector);
SystemDisk[j]->DataSelector = 0;

if (SystemDisk[j]->DriveInfoSelector)
__dpmi_free_dos_memory(SystemDisk[j]->DriveInfoSelector);
SystemDisk[j]->DriveInfoSelector = 0;

SystemDisk[j]->PhysicalDiskHandle = 0;
NWFSFree(SystemDisk[j]);
SystemDisk[j] = 0;

#if (WINDOWS_98_UTIL)
r.x.ax = 0x440D; // generic IOCTL
r.h.bl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
r.h.ch = 0x08; // device category
r.h.cl = 0x6B; // unlock physical volume
int86(0x21, &r, &r);
#endif
continue;
}

r.h.ah = 0x08; // read drive parameters
r.h.dl = (0x80 | (j & 0x7F));

int86(0x13, &r, &r);

if (r.h.cflag)
{
if (SystemDisk[j]->RequestSelector)
__dpmi_free_dos_memory(SystemDisk[j]->RequestSelector);
SystemDisk[j]->RequestSelector = 0;

if (SystemDisk[j]->DataSelector)
__dpmi_free_dos_memory(SystemDisk[j]->DataSelector);
SystemDisk[j]->DataSelector = 0;

if (SystemDisk[j]->DriveInfoSelector)
__dpmi_free_dos_memory(SystemDisk[j]->DriveInfoSelector);
SystemDisk[j]->DriveInfoSelector = 0;

SystemDisk[j]->PhysicalDiskHandle = 0;
NWFSFree(SystemDisk[j]);
SystemDisk[j] = 0;

#if (WINDOWS_98_UTIL)
r.x.ax = 0x440D; // generic IOCTL
r.h.bl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
r.h.ch = 0x08; // device category
r.h.cl = 0x6B; // unlock physical volume
int86(0x21, &r, &r);
#endif
continue;
}

// translate drive geometry based on the total sectors
// reported by the Int 13 extension procedure.

heads = r.h.dh + 1;
sectors = ((WORD)r.h.cl & 0x003F);
cylinders = (dinfo.TotalSectors / (heads * sectors));

// make sure that cylinders are within the maximum value
// allowed by the Int 13 Extended Architecture. At present,
// this limit is 16 mega-tera sectors (2^64).

// assume the current IDE limits for cylinder count
if (cylinders > (ULONG) 65536)
{
if (SystemDisk[j]->RequestSelector)
__dpmi_free_dos_memory(SystemDisk[j]->RequestSelector);
SystemDisk[j]->RequestSelector = 0;

if (SystemDisk[j]->DataSelector)
__dpmi_free_dos_memory(SystemDisk[j]->DataSelector);
SystemDisk[j]->DataSelector = 0;

if (SystemDisk[j]->DriveInfoSelector)
__dpmi_free_dos_memory(SystemDisk[j]->DriveInfoSelector);
SystemDisk[j]->DriveInfoSelector = 0;

SystemDisk[j]->PhysicalDiskHandle = 0;
NWFSFree(SystemDisk[j]);
SystemDisk[j] = 0;

#if (WINDOWS_98_UTIL)
r.x.ax = 0x440D; // generic IOCTL
r.h.bl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
r.h.ch = 0x08; // device category
r.h.cl = 0x6B; // unlock physical volume
int86(0x21, &r, &r);
#endif
continue;
}

// Use the Phoenix method of drive translation
// to translate drive geometry for those drives
// that exceed 1024 cylinders in size.
//
// Phoenix Geometry Translation Table
// -----------------------------------
//
// Phys Cylinders Phys Heads Trans Cyl Trans Heads Max
// --------------------------------------------------------
// 1 <C<= 1024 1 <H<= 16 C = C H = H 528 MB
// 1024 <C<= 2048 1 <H<= 16 C = C/2 H = H*2 1.0 GB
// 2048 <C<= 4096 1 <H<= 16 C = C/4 H = H*4 2.1 GB
// 4096 <C<= 8192 1 <H<= 16 C = C/8 H = H*8 4.2 GB
// 8192 <C<= 16384 1 <H<= 16 C = C/16 H = H*16 8.4 GB
// 16384 <C<= 32768 1 <H<= 8 C = C/32 H = H*32 8.4 GB
// 32768 <C<= 65536 1 <H<= 4 C = C/64 H = H*64 8.4 GB
//
// LBA Assisted Translation Table
// ------------------------------
//
// (NOTE: The method below is an alternate method for
// translating large drives that does not place any limits
// on reported drive geometry. It has the disadvantage
// of always assuming 63 Sectors Per Track.)
//
// Range Sectors Heads Cylinders
// -----------------------------------------------------
// 1 MB <X< 528 MB 63 16 X/(63 * 16 * 512)
// 528 MB <X< 1.0 GB 63 32 X/(63 * 32 * 512)
// 1.0 GB <X< 2.1 GB 63 64 X/(63 * 64 * 512)
// 2.1 GB <X< 4.2 GB 63 128 X/(63 * 128 * 512)
// 4.2 GB <X< 8.4 GB 63 255 X/(63 * 255 * 512)
//

// Adjust cylinder and head dimensions until this drive
// presents a geometry with a cylinder count that is less
// than 1024 or Heads less than or equal to 255.

if (cylinders >= 1024)
{
while ((heads * 2) <= 256)
{
heads *= 2;
cylinders /= 2;
if (cylinders < 1024)
break;
}
}

if (FirstValidDisk == (ULONG)-1)
FirstValidDisk = j;

SystemDisk[j]->BytesPerSector = 512;
SystemDisk[j]->Cylinders = (LONGLONG) cylinders;
SystemDisk[j]->TracksPerCylinder = heads;
SystemDisk[j]->SectorsPerTrack = sectors;
SystemDisk[j]->driveSize = (LONGLONG)
(SystemDisk[j]->Cylinders *
SystemDisk[j]->TracksPerCylinder *
SystemDisk[j]->SectorsPerTrack *
SystemDisk[j]->BytesPerSector);
#if (VERBOSE)
NWFSPrint("disk-%d cyl-%d head-%d sector-%d (Int 13)\n",
(int)j,
(int)SystemDisk[j]->Cylinders,
(int)SystemDisk[j]->TracksPerCylinder,
(int)SystemDisk[j]->SectorsPerTrack);
#endif
}
else
{
// query the drive parameters with standard bios
r.h.ah = 0x08;
r.h.dl = (0x80 | (j & 0x7F));

int86(0x13, &r, &r);

if (r.h.cflag)
{
if (SystemDisk[j]->RequestSelector)
__dpmi_free_dos_memory(SystemDisk[j]->RequestSelector);
SystemDisk[j]->RequestSelector = 0;

if (SystemDisk[j]->DataSelector)
__dpmi_free_dos_memory(SystemDisk[j]->DataSelector);
SystemDisk[j]->DataSelector = 0;

if (SystemDisk[j]->DriveInfoSelector)
__dpmi_free_dos_memory(SystemDisk[j]->DriveInfoSelector);
SystemDisk[j]->DriveInfoSelector = 0;

SystemDisk[j]->PhysicalDiskHandle = 0;
NWFSFree(SystemDisk[j]);
SystemDisk[j] = 0;

#if (WINDOWS_98_UTIL)
r.x.ax = 0x440D; // generic IOCTL
r.h.bl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
r.h.ch = 0x08; // device category
r.h.cl = 0x6B; // unlock physical volume
int86(0x21, &r, &r);
#endif
continue;
}

if (FirstValidDisk == (ULONG)-1)
FirstValidDisk = j;

SystemDisk[j]->BytesPerSector = 512;
SystemDisk[j]->Cylinders =
(LONGLONG)(((WORD)((WORD)r.h.cl << 2) & 0x0300) |
(WORD)r.h.ch) + 1;
SystemDisk[j]->TracksPerCylinder = (r.h.dh + 1);
SystemDisk[j]->SectorsPerTrack = ((WORD)r.h.cl & 0x003F);
SystemDisk[j]->driveSize = (LONGLONG)
(SystemDisk[j]->Cylinders *
SystemDisk[j]->TracksPerCylinder *
SystemDisk[j]->SectorsPerTrack *
SystemDisk[j]->BytesPerSector);
#if (VERBOSE)
NWFSPrint("disk-%d cyl-%d head-%d sector-%d\n",
(int)j,
(int)SystemDisk[j]->Cylinders,
(int)SystemDisk[j]->TracksPerCylinder,
(int)SystemDisk[j]->SectorsPerTrack);
#endif
}

#if (WINDOWS_98_UTIL)
r.x.ax = 0x440D; // generic IOCTL
r.h.bl = (0x80 | (j & 0x7F)); // dos limit is 128 drives
r.h.ch = 0x08; // device category
r.h.cl = 0x6B; // unlock physical volume
int86(0x21, &r, &r);
#endif
TotalDisks++;
if (TotalDisks > MaximumDisks)
MaximumDisks = TotalDisks;

retCode = ReadDiskSectors(j, 0, Sector,
IO_BLOCK_SIZE / SystemDisk[j]->BytesPerSector,
IO_BLOCK_SIZE / SystemDisk[j]->BytesPerSector);
if (!retCode)
{
NWFSPrint("nwfs: disk-%d read error in ScanDiskDevices\n", (int)j);
continue;
}

NWFSCopy(&SystemDisk[j]->partitionSignature, &Sector[0x01FE], 2);

if (SystemDisk[j]->partitionSignature != 0xAA55)
{
#if (VERBOSE)
NWFSPrint("nwfs: partition signature 0xAA55 not found disk(%d)\n", (int)j);
#endif
NWFSSet(&SystemDisk[j]->PartitionTable[0].fBootable, 0, 64);
continue;
}
else
{
NWFSCopy(&SystemDisk[j]->PartitionTable[0].fBootable,
&Sector[0x01BE], 64);
}

// scan for Netware Partitions and detect 3.x and 4.x/5.x partition types
for (i=0, SystemDisk[j]->NumberOfPartitions = 0; i < 4; i++)
{
if (SystemDisk[j]->PartitionTable[i].nSectorsTotal)
SystemDisk[j]->NumberOfPartitions++;

if (SystemDisk[j]->PartitionTable[i].SysFlag == NETWARE_386_ID)
{
retCode = ReadDiskSectors(j,
SystemDisk[j]->PartitionTable[i].StartLBA,
Sector,
IO_BLOCK_SIZE / SystemDisk[j]->BytesPerSector,
IO_BLOCK_SIZE / SystemDisk[j]->BytesPerSector);
if (!retCode)
{
NWFSPrint("nwfs: disk-%d read error in ScanDiskDevices (part)\n", (int)j);
continue;
}

if (!NWFSCompare(Sector, NwPartSignature, 16))
SystemDisk[j]->PartitionVersion[i] = NW4X_PARTITION;
else
SystemDisk[j]->PartitionVersion[i] = NW3X_PARTITION;
}
}
}
}
NWFSFree(Sector);
return;
}

Phillip Susi wrote:

linux-os (Dick Johnson) wrote:


Yes, it's a very good model, in fact what I've been talking about.
However, several people who refused to read or understand, insisted
upon obtaining the exact same C/H/S that the machine claimed to
use when it was booted.


That's because if you don't use the same geometry that the bios reports when calculating the CHS addresses of the sectors you intend to load, you won't be requesting the right sectors from int 13.

So, since Linux doesn't destroy that information remaining in
the BIOS tables, I show how to make it available to a 'root' user.
Observation over several machines will show that the BIOS always
uses the same stuff for large media and, in fact, it has no choice.
Basically, this means that the first part of the boot-code, the
stuff that needs to be translated to fit into the int 0x13 registers,
needs to be below 1024 cylinders, 63 sectors-track, and 256 heads.
Trivial... even LILO was able to do that! Once the machine boots
past the requirement to use the BIOS services, it's a CHS=NOP.


Generally yes, modern large disks will get clamped at 1024 cylinders, 255 heads, and 63 sectors. You seem to be arguing that this will always be the case. If that is so, then the kernel doesn't need to store these values since it is known a priori does it? But it isn't always going to be 255/63, there are some bioses ( I forget which ) that cap the number of heads at 240, and disks that are smaller than 8 gigs also will have less than 255 heads.




-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/