en:docs:kernel:doskrnl

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en:docs:kernel:doskrnl [2023/11/26 15:26] – [CONFIG.SYS] prokusheven:docs:kernel:doskrnl [2024/05/25 02:43] (current) – prokushev
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 +{{page>en:templates:dosint}}
 +
 ====== DOSKRNL ====== ====== DOSKRNL ======
  
-DOSKRNL is a specialized DOS kernel changed to support DOS in MVM.+DOSKRNL is a specialized FreeDOS kernel changed to support DOS in MVM. Mostly all FAT code removed as well as CONFIG.SYS parser. So it smaller in compare with original FreeDOS kernel. Also image format changed from exe to raw binary because slightly different load logic. 
 + 
 +===== Initialization ===== 
 + 
 +DOSKRNL loaded at address differ from standard DOS 0060:0000 address. On test environment it was loaded to 0280:00, but [[https://archive.org/download/IBMOS2TechnicalDocumentation/KGUIDE20.PDF|OS/2 v 2.0 Kernel Design Guide]] says it is at 0070:0000. Later documentation says nothing about loading address. osFree DOSKRNL expects unknown load address, but in low address of conventional memory. Refer [[https://archive.org/download/IBMOS2TechnicalDocumentation/KGUIDE20.PDF|OS/2 v 2.0 Kernel Design Guide]] for memory map and initialization information. 
 + 
 +On DOSKRNL startup registers are following: 
 + 
 +  * CS:IP - starting point 
 +  * SS:BP - pointer to the DOSKRNL init structure (also referenced as VDOS init in IBM documents) 
 +  * SS:SP - stack pointer (size around 800 bytes)
  
-===== Startup =====+Interrupts disabled.
  
-On DOSKRNL start SS:BP contains some structure which contains initial information for DOS kernel. Exact structure format not know. SS:SP contains stack pointer (initially point to area after init structure, size around 400 bytes)+DOSKRNL init structure:
  
 ^ Offset ^ Size ^ Description ^ ^ Offset ^ Size ^ Description ^
Line 16: Line 28:
 | 14     | 4    | Far pointer to SHELL (filepath only) | | 14     | 4    | Far pointer to SHELL (filepath only) |
 | 18     | 4    | Far pointer to SHELL (arguments) | | 18     | 4    | Far pointer to SHELL (arguments) |
-| 22     | 4    | Pointer to linked list of VDD | +| 22     | 4    | Far pointer to linked list of VDD | 
-| 25     | 1    | Current drive (0-A, 1-B,...)| +| 26     | 1    | Current drive (1-A, 2-B, 3-C, ...)| 
-| 26     | 1    | Boot drive (0-A, 1-B,...) | +| 27     | 1    | Boot drive (1-A, 2-B, 3-C, ...) | 
-| ????   | ???  | ???? |+| 28     | 1    | Last drive (1-A, 2-B, 3-C, ...) | 
 +| ???    | ???  | ??? |
  
-Memory map on DOSKRNL start:+DEVICES is ASCIIZ string with list of DOS devices to be loaded divided by 0AH
  
-| Init area         | [BP+0+BP+2-BP+4]:0 | +SHELL is ASCIIZ string. 
-| Free              | [BP+0]:0 | + 
-| DOSKRNL           | 60:0 | +SHELL arguments is ASCIIZ string (first byte is a string length, string ends with 0dh)
-| CMOS Data         | 40:0 | +
-| Interrupt vectors | 0:0  |+
  
-As in most DOS kernels, DOSKRNL moves initialization code to higher memory. But uses init structure, not BIOS INT 12h, for memory information.+VDD is linked list of structures:
  
-VDDs linked list (in init area) in standard DOS Device drivers format+VDDs linked list in standard DOS Device drivers format. Entry can be placed in HMA, so need to be sure A20 enabled for such entries. Named as DOSDDTYPE in DDK
  
 ^ offset ^ Size ^ Description ^ ^ offset ^ Size ^ Description ^
Line 38: Line 49:
 | :::    | ::: | Bit 15 = 1 if char device 0 if blk     | | :::    | ::: | Bit 15 = 1 if char device 0 if blk     |
 | :::    | ::: |  if bit 15 is 1                        | | :::    | ::: |  if bit 15 is 1                        |
-| :::    | ::: |    Bit 0 = 1 if Current sti device     | +| :::    | ::: |    Bit 0 = 1 if Current STDIN device     | 
-| :::    | ::: |    Bit 1 = 1 if Current sto output     | +| :::    | ::: |    Bit 1 = 1 if Current STDOUT output     | 
-| :::    | ::: |    Bit 2 = 1 if Current NUL device     | +| :::    | ::: |    Bit 2 = 1 if Current NULL device     | 
-| :::    | ::: |    Bit 3 = 1 if Current CLOCK dev      |+| :::    | ::: |    Bit 3 = 1 if Current CLOCK device      |
 | :::    | ::: |    Bit 4 = 1 if SPECIAL                | | :::    | ::: |    Bit 4 = 1 if SPECIAL                |
 | :::    | ::: |  Bit 14 is the IOCTL bit               | | :::    | ::: |  Bit 14 is the IOCTL bit               |
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 |  8     |  2  | Pointer to Device interrupt entry point | |  8     |  2  | Pointer to Device interrupt entry point |
 |  10    |  8  | character device name field. Character devices set a device name. For block devices the first byte is the number of units | |  10    |  8  | character device name field. Character devices set a device name. For block devices the first byte is the number of units |
 +
 +Memory map on DOSKRNL start:
 +
 +| Init area         | [BP+0+BP+2-BP+4]:0 |
 +| Free              | [BP+0]:0 |
 +| DOSKRNL           | ???:0 |
 +| Some data (VDD entries was found here) | ??? |
 +| CMOS Data         | 40:0 |
 +| Interrupt vectors | 0:0  |
 +
 +As in most DOS kernels, DOSKRNL moves initialization code to higher conventional memory. But uses init structure, not BIOS INT 12h, for memory information.
  
 DOSKRNL search and initialize XMS driver and moves some parts to HMA. Most other initialization things is same. DOSKRNL initializes standard device drivers and adds and initializes VDDs, passed via init structure. Some things (at least COMMAND.COM, device drivers) also passed via init structure. not CONFIG.SYS. At the present time interface not investigated well. DOSKRNL search and initialize XMS driver and moves some parts to HMA. Most other initialization things is same. DOSKRNL initializes standard device drivers and adds and initializes VDDs, passed via init structure. Some things (at least COMMAND.COM, device drivers) also passed via init structure. not CONFIG.SYS. At the present time interface not investigated well.
Line 60: Line 82:
   * DOS   * DOS
   * BREAK   * BREAK
 +  * FCBS
 +  * LASTDRIVE
  
 todo add more info here todo add more info here
  
 Also most of these setting can be adjusted via DOS Properties (aka DOS Settings). Refer [[https://archive.org/download/gg243731/gg243731_OS2_V2_0_Vol_2_DOS_and_Windows_Environment.pdf|OS/2 Version 2.0 Volume 2: DOS and Windows Environment]] for more information. Also most of these setting can be adjusted via DOS Properties (aka DOS Settings). Refer [[https://archive.org/download/gg243731/gg243731_OS2_V2_0_Vol_2_DOS_and_Windows_Environment.pdf|OS/2 Version 2.0 Volume 2: DOS and Windows Environment]] for more information.
 +
 +===== Properties =====
 +
 +  * COM_DIRECT_ACCESS
 +  * COM_HOLD
 +  * COM_RECEIVE_BUFFER_FLUSH
 +  * COM_SELECT
 +  * DOS_AUTOEXEC
 +  * DOS_BACKGROUND_EXECUTION
 +  * DOS_BREAK
 +  * DOS_DEVICE
 +  * DOS_FCBS
 +  * DOS_FCBS_KEEP
 +  * DOS_FILES
 +  * DOS_HIGH
 +  * DOS_LASTDRIVE
 +  * DOS_RMSIZE
 +  * DOS_SHELL
 +  * DOS_STARTUP_DRIVE
 +  * DOS_UMB
 +  * DOS_VERSION
 +  * DPMI_DOS_API
 +  * DPMI_MEMORY_LIMIT
 +  * DPMI_NETWORK_BUFF_SIZE
 +  * EMS_FRAME_LOCATION
 +  * EMS_HIGH_OS_MAP_REGION
 +  * EMS_LOW_OS_MAP_REGION
 +  * EMS_MEMORY_LIMIT
 +  * HW_NOSOUND
 +  * HW_ROM_TO_RAM
 +  * HW_TIMER
 +  * IDLE_SECONDS
 +  * IDLE_SENSITIVITY
 +  * INT_DURING_IO
 +  * KBD_ALTHOME_BYPASS
 +  * KBD_BUFFER_EXTEND
 +  * KBD_CTRL_BYPASS
 +  * KBD_RATE_LOCK
 +  * MEM_EXCLUDE_REGION
 +  * MEM_INCLUDE_REGION
 +  * MOUSE_EXCLUSIVE_ACCESS
 +  * PRINT_SEPARATE_OUTPUT
 +  * PRINT_TIMEOUT
 +  * SESSION_PRIORITY
 +  * VIDEO_8514A_XGA_IOTRAP
 +  * VIDEO_FASTPASTE
 +  * VIDEO_MODE_RESTRICTIONS
 +  * VIDEO_ONDEMAND_MEMORY
 +  * VIDEO_RETRACE_EMULATION
 +  * VIDEO_ROM_EMULATION
 +  * VIDEO_SWITCH_NOTIFICATION
 +  * VIDEO_WINDOW_REFRESH
 +  * XMS_HANDLES
 +  * XMS_MEMORY_LIMIT
 +  * XMS_MINIMUM_HMA 
  
 ===== API ===== ===== API =====