strategy(9E)							Driver Entry Points						      strategy(9E)

NAME

       strategy - perform block I/O

SYNOPSIS

       #include <sys/types.h>
       #include <sys/buf.h>
       #include <sys/ddi.h>
       #include <sys/sunddi.h>

       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. strat-
       egy() 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 strategy() routine's responsibility is to set up and initiate the transfer.

       In  general, strategy() should not block. It can, however, perform a kmem_cache_alloc(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 condition, 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_alloc(9F)

       Writing Device Drivers

SunOS 5.10							    6 Nov 2003							      strategy(9E)