STRATEGY(9E)STRATEGY(9E)NAMEstrategy - 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. stratā
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_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 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 ALSOioctl(9E), read(9E), write(9E), biodone(9F), bioerror(9F), buf(9S),
cb_ops(9S), kmem_cache_create(9F)
Writing Device Drivers
Nov 6, 2003 STRATEGY(9E)