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Text File | 1992-08-27 | 15.4 KB | 387 lines

HardBlocks specification 03/89 * Copyright 1988 Commodore-Amiga, Inc. All Rights Reserved * * This information is provided "as is"; no warranties are made. All * use is at your own risk. No liability or responsibility is assumed. hardblocks.h This file describes blocks of data that exist on a hard disk to describe that disk. They are not generically accessable to the user as they do not appear on any DOS drive. The blocks are tagged with a unique identifier, checksummed, and linked together. The four block types currently defined are RigidDiskBlock, BadBlockBlock, PartitionBlock, FileSysHeaderBlock, and LoadSegBlock. The root of these blocks is the RigidDiskBlock. The RigidDiskBlock must exist on the disk within the first RDB_LOCATION_LIMIT blocks. This inhibits the use of the zero cylinder in an AmigaDOS partition: although it is strictly possible to store the RigidDiskBlock data in the reserved area of a partition, this practice is discouraged since the reserved blocks of a partition are overwritten by "Format", "Install", "DiskCopy", etc. The recommended disk layout, then, is to use the first cylinder(s) to store all the drive data specified by these blocks: i.e. partition descriptions, file system load images, drive bad block maps, spare blocks, etc. This allocation range is described in the RigidDiskBlock. The RigidDiskBlock points to bad block, partition, file system and drive initialization description blocks. The bad block format is simply lists of pairs describing bad blocks and their replacements. The drive initialization description blocks are LoadSegBlock blocks that are loaded at boot time to perform drive-specific initialization when called with parameters both "C" style on the stack, and in assembler registers as follows: d0 = DriveInit(lun,rdb,ior)(d0/a0/a1) where lun is the SCSI logical unit number (needed to construct SCSI commands), rdb is an image of the RigidDiskBlock and cannot be altered, and ior is a standard IO request block that can be used to access the drive with synchronous DoIO() calls. The result of DriveInit is either -1, 0, or 1. -1 reports an error occurred and drive initialization cannot continue, zero reports success. In both cases, the code is unloaded. 1 reports success, and causes the code to be kept loaded. Furthermore, this resident code is to be called whenever a reset is detectected on the SCSI bus. The FileSysHeaderBlock entries contain code for alternate file handlers to be used by partitions that specify them. There are several strategies that can be used to determine which of them to load. The most robust would scan all drives for those that are both required by partitions and have the highest fhb_Version, and load those. Whatever method is used, the loaded file handlers are added to the exec resource FileSystem.resource, where they are used as needed to mount disk partitions. The PartitionBlock entries contains most of the data necessary to add each device to the system. They replace the Mount & DEVS:MountList mechanism for adding these devices. The only items required by the expansion.library MakeDosNode function which are not in this partition block are the exec device name and unit, which is expected to be known by the reader of the block. The file system to be used is specified in the pb_Environment. If it is not the default file system (i.e. 'DOS\0'), the node created by MakeDosNode is modified as specified in a FileSystem.resource's FileSysEntry before adding it to the dos list. Though only 512 byte blocks are currently supported by the file system, this proposal tries to be forward-looking by making the block size explicit, and by using only the first 256 bytes for all blocks but the LoadSeg data. RigidDiskBlock rdb_ID == 'RDSK' rdb_SummedLongs == 64 rdb_ChkSum block checksum (longword sum to zero) rdb_HostID SCSI Target ID of host This is the initiator ID of the creator of this RigidDiskBlock. It is intended that modification of the RigidDiskBlock, or of any of the blocks pointed to by it, by another initiator (other than the one specified here) be allowed only after a suitable warning. The user is then expected to perform an audio lock out ("Hey, is anyone else setting up SCSI stuff on this bus?"). The rdb_HostID may become something other than the initiator ID when connected to a real network: that is an area for future standardization. rdb_BlockBytes size of disk blocks This must be 512 for a disk with any AmigaDOS partitions on it. rdb_Flags longword of flags RDBF._LAST no disks exist to be configured after this one on this controller. RDBF._LASTLUN no LUNs exist to be configured greater than this one at this SCSI Target ID RDBF._LASTTID no Target IDs exist to be configured greater than this one on this SCSI bus RDBF._DISKID rdb_Disk... identification variables below contain valid data. RDBF._CTRLRID rdb_Controller... identification variables below contain valid data. These fields point to other blocks on the disk which are not a part of any filesystem. rdb_BadBlockList optional bad block list A singly linked list of blocks of type PartitionBlock rdb_PartitionList optional first partition block A singly linked list of blocks of type PartitionBlock rdb_FileSysHeaderList optional file system header block A singly linked list of blocks of type FileSysHeaderBlock rdb_DriveInit optional drive-specific init code A songly linked list of blocks of type LoadSegBlock containing initialization code. Called as DriveInit(lun,rdb,ior)(d0/a0/a1). rdb_Reserved1 set to $ffffffffs These are reserved for future block lists. Since NULL for block lists is $ffffffff, these reserved entries must be set to $ffffffff. These fields describe the physical layout of the drive. rdb_Cylinders number of drive cylinders rdb_Sectors sectors per track rdb_Heads number of drive heads rdb_Interleave interleave This drive interleave is independent from, and unknown to, the DOS's understanding of interleave as set in the partition's environment vector. rdb_Park landing zone cylinder rdb_Reserved2 set to zeros These fields are intended for ST506 disks. They are generally unused for SCSI devices and set to zero. rdb_WritePreComp starting cylinder: write precompensation rdb_ReducedWrite starting cylinder: reduced write current rdb_StepRate drive step rate rdb_Reserved3 set to zeros These fields are used while partitions are set up to constrain the partitionable area and help describe the relationship between the drive's logical and physical layout. rdb_RDBlocksLo low block of the range allocated for blocks described here. Replacement blocks for bad blocks may also live in this range. rdb_RDBlocksHi high block of this range (inclusive) rdb_LoCylinder low cylinder of partitionable disk area Blocks described by this include file will generally be found in cylinders below this one. rdb_HiCylinder high cylinder of partitionable data area Usually rdb_Cylinders-1. rdb_CylBlocks number of blocks available per cylinder This may be rdb_Sectors*rdb_Heads, but a SCSI disk that reserves one block per cylinder for bad block mapping uses rdb_Sectors*rdb_Heads-1. rdb_AutoParkSeconds The number of seconds to wait before parking drive heads automatically. If zero, this feature is not desired. rdb_Reserved4 set to zeros These fields are of the form available from a SCSI Identify command. Their purpose is to help the user identify the disk during setup. Entries exist for both controller and disk for non-embedded SCSI disks. rdb_DiskVendor The vendor name of the disk rdb_DiskProduct The product name of the disk rdb_DiskRevision The revision code of the disk rdb_ControllerVendor The vendor name of the disk controller rdb_ControllerProduct The product name of the disk controller rdb_ControllerRevision The revision code of the disk controller rdb_Reserved5 BadBlockBlock The end of data occurs when bbb_Next is null ($ffffffff), and the summed data is exhausted. bbb_ID == 'BADB' bbb_SummedLongs size of this checksummed structure Note that this is not 64 like most of the other structures. This is the number of valid longs in this image, and can be from 6 to rdb_BlockBytes/4. The latter is the best size for all intermediate blocks. bbb_ChkSum block checksum (longword sum to zero) bbb_HostID SCSI Target ID of host This describes the initiator ID for the creator of these blocks. (see the rdb_HostID discussion) bbb_Next block number of the next BadBlockBlock bbb_Reserved bbb_BlockPairs pairs of block remapping information The data starts here and continues as long as indicated by bbb_SummedLongs-6: e.g. if bbb_SummedLongs is 128 (512 bytes), 61 pairs are described here. PartitionBlock Note that while reading these blocks you may encounter partitions that are not to be mounted because the pb_HostID does not match, or because the pb_DriveName is in use and no fallback strategy exists, or because PBF._NOMOUNT is set. They may be mounted but not made bootable because PBF._BOOTABLE is not set. pb_ID == 'PART' pb_SummedLongs == 64 pb_ChkSum block checksum (longword sum to zero) pb_HostID SCSI Target ID of host This describes the initiator ID for the owner of this partition. (see the rdb_HostID discussion) pb_Next block number of the next PartitionBlock pb_Flags see below for defines PBF._BOOTABLE this partition is intended to be bootable (e.g. expected directories and files exist) pb_Reserved1 pb_DevFlags preferred flags for OpenDevice pb_DriveName preferred DOS device name: BSTR form This name is not to be used if it is already in use. pb_Reserved2 will always be at least 4 longwords so that the ram image of this record may be converted to the parameter packet to the expansion.library function MakeDosNode pb_Reserved2 filler to 32 longwords The specification of the location of the partition is one of the components of the environment, below. If possible, describe the partition in a manner that tells the DOS about the physical layout of the partition: specifically, where the cylinder boundaries are. This allows the DOS's smart block allocation strategy to work. pb_Environment environment vector for this partition de_TableSize size of Environment vector de_SizeBlock == 128 de_SecOrg == 0 de_Surfaces number of heads (see layout discussion above) de_SectorPerBlock == 1 de_BlocksPerTrack blocks per track (see layout discussion above) de_Reserved DOS reserved blocks at start of partition. Must be >= 1. 2 is recommended. de_PreAlloc DOS reserved blocks at end of partition Valid only for filesystem type DOS^A (the fast file system). Zero otherwise. de_Interleave DOS interleave Valid only for filesystem type DOS^@ (the old file system). Zero otherwise. de_LowCyl starting cylinder de_HighCyl max cylinder de_NumBuffers initial # DOS of buffers. de_BufMemType type of mem to allocate for buffers The second argument to AllocMem(). de_MaxTransfer max number of bytes to transfer at a time de_Mask address mask to block out certain memory $00ffffff for DMA devices. de_BootPri Boot priority for autoboot Suggested value: zero. Keep less than five, so it won't override a boot floppy. de_DosType ASCII string showing filesystem type; DOS^@ ($444F5300) is old filesystem, DOS^A ($444F5301) is fast file system. pb_EReserved reserved for future environment vector FileSysHeaderBlock fhb_ID == 'FSHD' fhb_SummedLongs == 64 fhb_ChkSum block checksum (longword sum to zero) fhb_HostID SCSI Target ID of host This describes the initiator ID for the creator of this block. (see the rdb_HostID discussion) fhb_Next block number of next FileSysHeaderBlock fhb_Flags see below for defines fhb_Reserved1 The following information is used to construct a FileSysEntry node in the FileSystem.resource. fhb_DosType file system description This is matched with a partition environment's de_DosType entry. fhb_Version release version of this load image Usually MSW is version, LSW is revision. fhb_PatchFlags patch flags These are bits set for those of the following that need to be substituted into a standard device node for this file system, lsb first: e.g. 0x180 to substitute SegList & GlobalVec fhb_Type device node type: zero fhb_Task standard dos "task" field: zero fhb_Lock not used for devices: zero fhb_Handler filename to loadseg: zero placeholder fhb_StackSize stacksize to use when starting task fhb_Priority task priority when starting task fhb_Startup startup msg: zero placeholder fhb_SegListBlocks first of linked list of LoadSegBlocks: Note that if the fhb_PatchFlags bit for this entry is set (bit 7), the blocks pointed to by this entry must be LoadSeg'd and the resulting BPTR put in the FileSysEntry node. fhb_GlobalVec BCPL global vector when starting task Zero or -1. fhb_Reserved2 (those reserved by PatchFlags) fhb_Reserved3 LoadSegBlock The end of data occurs when lsb_Next is null ($ffffffff), and the summed data is exhausted. lsb_ID == 'LSEG' lsb_SummedLongs size of this checksummed structure Note that this is not 64 like most of the other structures. This is the number of valid longs in this image, like bbb_SummedLongs. lsb_ChkSum block checksum (longword sum to zero) lsb_HostID SCSI Target ID of host This describes the initiator ID for the creator of these blocks. (see the rdb_HostID discussion) lsb_Next block number of the next LoadSegBlock lsb_LoadData data for "loadseg" The data starts here and continues as long as indicated by lsb_SummedLongs-5: e.g. if lsb_SummedLongs is 128 (512 bytes), 123 longs of data are valid here. filesysres.[hi] The FileSysResource is created by the first code that needs to use it. It is added to the resource list for others to use. (Checking and creation should be performed while Forbid()). FileSysResource fsr_Node on resource list fsr_Creator name of creator of this resource fsr_FileSysEntries list of FileSysEntry structs FileSysEntry fse_Node on fsr_FileSysEntries list ln_Name is of creator of this entry fse_DosType DosType of this FileSys fse_Version release version of this FileSys Usually MSW is version, LSW is revision. fse_PatchFlags bits set for those of the following that need to be substituted into a standard device node for this file system: e.g. $180 for substitute SegList & GlobalVec fse_Type device node type: zero fse_Task standard dos "task" field fse_Lock not used for devices: zero fse_Handler filename to loadseg (if SegList is null) fse_StackSize stacksize to use when starting task fse_Priority task priority when starting task fse_Startup startup msg: FileSysStartupMsg for disks fse_SegList segment of code to run to start new task fse_GlobalVec BCPL global vector when starting task no more entries need exist than those implied by fse_PatchFlags, so entries do not have a fixed size.