Understanding Windows NT Internals - Part 4
0 likes30 views
Windows NT internals refer to the inner workings of the Windows NT operating system. It includes the system architecture, critical data, and how the system is organized.
Understanding Windows NT Internals - Part 4
- 1. WINDOWS NT INTERNALS – 04 Computer Call September 22, 1997
- 2. WINDOWS NT AND OBJECTIVES • Design of NT object-based • Kernel and Execute modules define • Driver is allowed to access some object fields and access functions • I/O Manager objects are partially opaque to a driver
- 3. NT Objects Win 32 Objects • No external visible names • Not managed by Object Manager • Use pointer to the Object body • Visible names • Managed by Object Manager • Use Handles to the Object body
- 4. I/O REQUEST PACKETS • I/O packet driver in NT • IRPs are data structures which contains work order
- 5. OPERATIONS OF IRPS • User specifies some function • I/O Manager allocates IRP from non paged system memory • IRP is passed to driver dispatch routine • Dispatch routine passes IRP to driver’s start I/O routine • Start I/O routine uses contents of the IRP and sets up device operation • On operation completion, Dpc For lsr routine stores final status code in IRP and sends it back to I/O Manager • I/O Manager sends the user final status
- 6. LAYOUT OF IRP IO Status Major Function; Minor function; Union { Struct{} Read; Struct{}Write; Struct{}Device located; }parameters IRP IO-STATUS-BLOCK Status; Information; IO-STACK-LOCATION Two sections in IRP •Header area containing book keeping information •One or more parameter blocks called I/O stack locations
- 7. IRP HEADER • IO status- holds final status of the I/O operation Status field-STATUS XXX value Information fiels- 0(error) value(no.of bites transferred)
- 8. I/O STACK LOCATIONS • Major functions- hold function code(IRP-MJ-XXX function) • Minor function- used by file system and SCSI drivers • Parameters- Operation to perform Struct Read-parameters for IRP-MJ-READ Struct Write- parameters for IRP-MJ-WRITE Struct Device IO control- parameters for IRP-MJ- DEVICE-CONTROL and IRP-MJ-INTERNAL-DEVICE- CONTROL
- 9. DRIVER OBJECT • A catalog that contains pointers to various driver functions
- 10. OPERATION OF DRIVER OBJECT • I/O Manager creates Driver Object • Driver Entry routine loads pointer to other driver functions • I/O Manager uses associated dispatch routine of Driver Object • I/O Manager uses Driver Object to locate the driver’s start I/O routine • I/O Manager deletes the Driver Objects • I/O Manager uses Driver Object to find unload routine
- 11. LAYOUT OF DRIVER OBJECT Device Object Device Object Device Object Driver Object Driver Start IO Driver Unload Major Function . . Start I/O routine` Unload Routine Dispatch Routine Dispatch Routine
- 12. DEVICE OBJECTS AND DEVICE EXTENSIONS • Keep information about a device’s characteristics and state • One device object for each virtual, logical, and physical device on the system
- 13. OPERATION OF DEVICE OBJECTS • Driver Entry routine creates a Device Object • I/O Manager uses a pointer in the Device Object to locate corresponding Driver Object •Driver routines use the Device Object to locate corresponding Device Extension •Driver’s Unload routine deletes the Device Object
- 14. LAYOUT OF DEVICE OBJECT Driver Object Pending IRP Pending IRP Device Object Next Device Flags Driver Object Current lrp Device Extension Device Queue Object Current IRP Device Extension
- 15. DEVICE EXTENSION • Used to hold any information associated with a particular device • Block of non=paged pool that the I/O Manager attaches to Device object
- 16. LAYOUT DEVICE EXTENSION Controller Object Device Extension Information Device Object Device State Interrupt Object Controller Object Adapter Object Device Object Interrupt Object Adapter Object
- 17. CONTROLLER AND CONTROLLER EXTENSIONS • A token that can be owned by only one device at a time Operation of Controller Objects • Driver Entry routine creates controller object and stores its address in Device Extension • Start I/O asks for exclusive ownership of controller object • I/O Manager grants ownerships and calls controller control routine which starts I/O operation • After completion of device operation, driver’s Dpc For lsr routine releases the controller object • Unload routine deletes the controller object
- 19. ADAPTER OBJECTS • Used to prevent arguments over DMA hardware • One Adapter Object for each DMA data transfer channel • Manage mapping registers used to map scattered physical pages of a user’s buffer onto contiguous range of address Operations on Adapter Objects • HAL creates Adapter Objects for all DMA channels detected at bootsteap time • Driver Entry routine locates the Adapter Object and stores pointers in the Device or Controller Extension • Start I/O routine requests owner ship of Adapter Object • I/O Manager calls the drivers Adapter Control routine • Dpc For lsr routine releases the Adapter Object
- 20. LAYOUT OF ADAPTER OBJECT Device Controller Extension Adapter Ptr Map RegCount Adapter Object
- 21. INTERRUPT OBJECTS • Give the Kernel’s interrupt dispatcher a way to find right ISR Operation of Interrupt Object Driver Entry routine creates Interrupt Object Kernel’s interrupt dispatcher locates the ISR Unload routine deletes the Interrupt Object
- 22. LAYOUT OF AN INTERRUPT OBJECT Device or Controller Extension Interrupt Ptr Interrupt Object Interrupt Service Routine