Unix/Linux Go Back    

Unix Version 7 - man page for pk (v7 section 4)

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)

PK(4)											    PK(4)

       pk - packet driver

       The  packet  driver implements a full-duplex end-to-end flow control strategy for machine-
       to-machine communication.  Packet driver protocol is established by calling pkon(2) with a
       character device file descriptor and a desired packet size in bytes.  The packet size must
       be a power of 2, 32<=size<=4096.  The file descriptor must represent an 8-bit  data  path.
       This is normally obtained by  setting the device in raw mode (see ioctl(2)).

       The  actual  packet size, which may be smaller than the desired packet size, is arrived at
       by negotiation with the packet driver at the remote end of the data link.

       The packet driver maintains two data areas for incoming and outgoing packets.  The  output
       area  is  needed to implement retransmission on errors, and arriving packets are queued in
       the input area.	Data arriving for a file not open for reading  is  discarded.	Initially
       the size of both areas is set to two packets.

       It  is  not necessary that reads and writes be multiples of the packet size although there
       is less system overhead if they are.  Read operations return the maximum  amount  of  data
       available from the input area up to the number of bytes specified in the system call.  The
       buffer sizes in write operations are not normally transmitted across the  link.	 However,
       writes of zero length are treated specially and are reflected at the remote end as a zero-
       length read.  This facilitates marking the serial  byte	stream,  usually  for  delimiting

       When  one  side	of  a  packet driver link is shut down by close(2)or pkoff (see pkon(2)),
       read(2) on the other side will return 0, and write on the other side will raise a  SIGPIPE

       pkon(2), pkopen(3)

					      local					    PK(4)
Unix & Linux Commands & Man Pages : ©2000 - 2018 Unix and Linux Forums

All times are GMT -4. The time now is 09:39 PM.