Manual Pages for UNIX Operating System command usage for man strategy

Driver Entry Points                                  strategy(9E)



NAME
     strategy - perform block I/O

SYNOPSIS
     #include 
     #include 
     #include 
     #include 



     int prefixstrategy(struct buf *bp);


INTERFACE LEVEL
     Architecture independent level 1 (DDI/DKI). This entry point
     is required for block devices.

PARAMETERS
     bp     Pointer to the buf(9S) structure.


DESCRIPTION
     The  strategy()  routine  is  called   indirectly   (through
     cb_ops(9S))  by  the kernel to read and write blocks of data
     on the block device. strategy() may also be called  directly
     or  indirectly  to  support the raw character interface of a
     block device (read(9E), write(9E) and ioctl(9E)). The  stra-
     tegy()  routine's  responsibility  is to set up and initiate
     the transfer.


     In general, strategy() should not block.  It  can,  however,
     perform  a  kmem_cache_create(9F)  with both the KM_PUSHPAGE
     and KM_SLEEP flags set, which might block,  without  causing
     deadlock in low memory situations.

RETURN VALUES
     The strategy() function must return 0. On  an  error  condi-
     tion,  it  should  call  bioerror(9F)  to set b_flags to the
     proper error code, and call biodone(9F). Note that a partial
     transfer is not considered to be an error.

SEE ALSO
     ioctl(9E), read(9E), write(9E),  biodone(9F),  bioerror(9F),
     buf(9S), cb_ops(9S), kmem_cache_create(9F)


     Writing Device Drivers






SunOS 5.11           Last change: 6 Nov 2003                    1