physiock(D3)physiock(D3)NAMEphysiock - validate and issue a raw I/O request
SYNOPSIS
#include <sys/types.h>
#include <sys/buf.h>
#include <sys/uio.h>
#include <sys/ddi.h>
int physiock(void (*strat)(), buf_t *bp, dev_t dev, int rwflag,
daddr_t nblocks, uio_t *uiop);
Arguments
strat Address of the driver strategy(D2) routine, or similar
function.
bp Pointer to the buf(D4) structure describing the I/O request.
dev External device number.
rwflag Flag indicating whether the access is a read or a write.
nblocks Number of blocks that the logical device dev can support.
uiop Pointer to the uio(D4) structure that defines the user space of
the I/O request.
DESCRIPTIONphysiock is called by the character interface ioctl(D2), read(D2), and
write(D2) routines of block drivers to help perform unbuffered I/O while
maintaining the buffer header as the interface structure.
Return Values
physiock returns 0 if the result is successful, or the appropriate error
number on failure. If a partial transfer occurs, the uio structure is
updated to indicate the amount not transferred and an error is returned.
If a read is performed at the end of the device, 0 is returned.
ENOSPC
An attempt is made to read beyond the end of the device.
ENOSPC
An attempt is made to write at or beyond the end of the device.
EFAULT
The user memory is not valid.
EAGAIN
physiock could not lock all of the pages.
EINVAL
The offset is not a multiple of NBPSCTR.
EBUSY
There is not enough kernel memory available to map the user pages to
kernel virtual memory.
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physiock(D3)physiock(D3)USAGEphysiock performs the following functions:
verifies the requested transfer is valid by checking if the offset
is at or past the end of the device (this check is bypassed if the
size parameter argument nblocks is zero) and that the offset is a
multiple of NBPSCTR
sets up a buffer header describing the transfer
faults pages in and locks the pages impacted by the I/O transfer so
they can't be swapped out
calls the driver strategy routine passed to it (strat)
sleeps until the transfer is complete and is awakened by a call to
biodone(D3) from the driver's I/O completion handler
performs the necessary cleanup and updates, then returns to the
driver routine
A transfer using physiock is considered valid if the specified data
location exists on the device, and the user has specified a storage area
large enough that exists in user memory space.
If bp is set to NULL, a buffer is allocated temporarily and freed after
the transfer completes.
If rwflag is set to B_READ, the direction of the data transfer will be
from the kernel to the user's buffer. If rwflag is set to B_WRITE, the
direction of the data transfer will be from the user's buffer to the
kernel.
One block is equal to NBPSCTR bytes. NBPSCTR is defined in sys/param.h.
Level
Base only.
Synchronization Constraints
Can sleep.
Driver-defined basic locks and read/write locks may not be held across
calls to this function.
Driver-defined sleep locks may be held across calls to this function.
REFERENCESbuf(D4), ioctl(D2), read(D2), strategy(D2), uio(D4), write(D2),
uiophysio(D3X)
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