en:docs:kernel:doskrnl

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en:docs:kernel:doskrnl [2024/05/24 02:01] – prokusheven:docs:kernel:doskrnl [2024/05/25 02:43] (current) – prokushev
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 ===== Initialization ===== ===== Initialization =====
  
-DOSKRNL loaded at address differ from standard DOS 0060:0000 address, but at 0070:0000. 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.+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: On DOSKRNL startup registers are following:
  
   * CS:IP - starting point   * CS:IP - starting point
-  * SS:BP - pointer to the DOSKRNL init structure (also refered as VDOS init in IBM documents)+  * SS:BP - pointer to the DOSKRNL init structure (also referenced as VDOS init in IBM documents)
   * SS:SP - stack pointer (size around 800 bytes)   * SS:SP - stack pointer (size around 800 bytes)
  
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 | 26     | 1    | Current drive (1-A, 2-B, 3-C, ...)| | 26     | 1    | Current drive (1-A, 2-B, 3-C, ...)|
 | 27     | 1    | Boot drive (1-A, 2-B, 3-C, ...) | | 27     | 1    | Boot drive (1-A, 2-B, 3-C, ...) |
-| ????   | ???  | ???? |+| 28     | 1    | Last drive (1-A, 2-B, 3-C, ...) | 
 +| ???    | ???  | ??? |
  
 DEVICES is ASCIIZ string with list of DOS devices to be loaded divided by 0AH DEVICES is ASCIIZ string with list of DOS devices to be loaded divided by 0AH
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 SHELL is ASCIIZ string. SHELL is ASCIIZ string.
  
-SHELL arguments is ASCIIZ string (first byte is as string length, string ends with 0dh)+SHELL arguments is ASCIIZ string (first byte is a string length, string ends with 0dh)
  
 VDD is linked list of structures: VDD is linked list of structures:
  
-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.+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 ^
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   * DOS   * DOS
   * BREAK   * BREAK
 +  * FCBS
 +  * LASTDRIVE
  
 todo add more info here todo add more info here