trunc_page(9r) [osf1 man page]

trunc_page(9r)															    trunc_page(9r)

NAME

       trunc_page - General: Truncates the specified address

SYNOPSIS

       #include <mach/vm_param.h>

       vm_offset_t trunc_page(
	       vm_offset_t address );

ARGUMENTS

       Specifies the address that is being truncated to a page boundary.

DESCRIPTION

       The trunc_page routine truncates the specified address to be aligned on a page boundary. This routine shields the driver writer from having
       to know the page size of the system, which could vary in different CPU architectures and on different CPU types within the  same  architec-
       ture.  Typically,  a device driver calls trunc_page in preparation for doing a DMA operation on a user's buffer. The value returned by this
       routine is used in the call to the vm_map_pageable routine. To use this routine, the  driver  writer  must  include  the  <mach/vm_param.h>
       header file in the driver.

RETURN VALUES

       The trunc_page routine returns an address truncated to a page boundary.

SEE ALSO

       Routines: current_task(9r), round_page(9r), vm_map_pageable(9r)

																    trunc_page(9r)

wakeup(9r)																wakeup(9r)

NAME

       wakeup - General: Wakes up all processes sleeping on a specified address

SYNOPSIS

       void wakeup(
	       caddr_t channel );

ARGUMENTS

       Specifies the address on which the wakeup is to be issued.

DESCRIPTION

       The wakeup routine wakes up all processes sleeping on the address specified by the channel argument. All processes sleeping on this address
       are awakened and made ready to be scheduled according to the priorities they specified when they went to sleep. It is possible  that  there
       are  no	processes sleeping on the channel at the time the wakeup is issued. This situation can occur for a variety of reasons and does not
       represent an error condition.

       The sleep and wakeup routines block and unblock a process. Generally, a device driver issues these routines on behalf of a process request-
       ing I/O while a transfer is in progress. That is, a process requesting I/O is put to sleep on an address associated with the request by the
       appropriate device driver routine. When the transfer has asynchronously completed, the device driver interrupt  service	routine  issues  a
       wakeup on the address associated with the completed request. This action makes the relevant process to be scheduled.

       The  process  resumes  execution  within  the  relevant	device driver routine at the point immediately following the request to sleep. The
       driver, on behalf of the process, can then determine whether the condition for which it was sleeping (in this example, completion of an I/O
       request)  has been removed.  If so, it can continue on to complete the I/O request. Otherwise, the appropriate driver routine can decide to
       put the process back to sleep to await removal of the indicated condition.

RETURN VALUES

       None

SEE ALSO

       Routines: mpsleep(9r), sleep(9r)

																	wakeup(9r)