×

System and method for directly executing user DMA instruction from user controlled process by employing processor privileged work buffer pointers

  • US 5,347,634 A
  • Filed: 03/15/1990
  • Issued: 09/13/1994
  • Est. Priority Date: 03/15/1990
  • Status: Expired due to Term
First Claim
Patent Images

1. A device for transferring data processing commands and associated data between a user'"'"'s host system, having a main memory and host processor, and an external data processing system via user controlled direct memory access (DMA) comprising:

  • a work buffer in said main memory which is locked for a DMA controlling user process of said host processor, said work buffer storing said data processing commands and associated data for said DMA controlling user process;

    a work buffer pointer register containing a work buffer pointer to said work buffer for said DMA controlling user process, said work buffer pointer being unique to said DMA controlling user process and said host processor having privileged access to said work buffer pointer register whereby said work buffer pointer is unmodifiable by said DMA controlling user process either directly or indirectly; and

    means responsive to a user DMA instruction from said DMA controlling user process for reading data processing commands and associated data specified in said user DMA instruction from said work buffer starting at the address pointed to by said work buffer pointer and for transferring, via DMA, said data processing commands and associated data from said work buffer to said external data processing system.

View all claims
  • 2 Assignments
Timeline View
Assignment View
    ×
    ×