Porting SCO OpenServer 5 STREAMS drivers and modules

SCO OpenServer 5 Release 5 provides a SVID 3-compatible user-level STREAMS implementation. This provides much of the System V Release 4 functionality that is in SVR5, but does not include features such as auto-push modules and STREAMS-based tty devices.

The SCO OpenServer 5 Release 5 kernel implementation and interface is based on the System V Release 3 implementation. It includes support for many System V Release 4 features, but the internal implementation does not always match that of SCO SVR5 1 and 2 and SVR5.

The SCO OpenServer 5 Release 5 kernel is quite different from the SVR5 kernel, which means that STREAMS drivers and modules will require significant modifications for non-STREAMS code. See ``Porting drivers to DDI 8''.

For more information about the new features of DDI 8 which impact how STREAMS drivers and modules should be implemented, see ``Implementing STREAMS drivers and modules in DDI 8''. In addition, please note the following specific points when porting SCO OpenServer 5 STREAMS drivers to SVR5:

• When porting STREAMS drivers between operating system platforms, check the <sys/stream.h> header files and documentation to ensure that the structures, message types, and kernel functions used in the driver conform to those supported on the target system.

• Both the SCO OpenServer 5 Release 5 and SVR5 kernels allocate STREAMS buffers and control structures dynamically. This is a more robust implementation for the system but may affect drivers that assume that allocated STREAMS buffers are physically contiguous. When porting SCO OpenServer 5 drivers to SVR5, many calls to allocb(D3str) can be replaced with calls to allocb_physreq(D3str), and the complicated code required to safeguard the integrity of the allocated memory can be removed.

• The SVR5 STREAMS interface is multithreaded, as is the SCO OpenServer 5 STREAMS interface. This enhances the performance of multithreaded network adapter drivers that are implemented on top of STREAMS. In SCO OpenServer 5, the initialization code calls sdistributed(D3oddi) to register a multithreaded STREAMS driver. In DDI 8, a driver is registered as being multithreaded by setting the D_MP flag in the drv_flags member of the drvinfo(D4) structure as described in ``Registering STREAMS drivers and modules''. See ``Multithreaded drivers'' for more information.

The following table summarizes the differences between the STREAMS functions in the ODDI (which is essentially based on SVR3 STREAMS) and those in DDI 8 (which includes SVR4 STREAMS and SCO SVR5 1 and 2 modifications to support multiprocessing). See the manual pages for full details about using each of these functions. Note that some ODDI functions are not supported on SVR5, either because they provided functionality that was specific to SCO OpenServer 5, or because they were made obsolete by the implementation of STREAMS in SVR4, SCO SVR5 1 and 2, or SVR5.

allocb(D3str)	For memory-mapped I/O, use esballoc(D3str).
backq(D3str)	This function is obsolete.
bcanput(D3str)	See usage restrictions on manual page.
bufcall(D3str)	Returns a value of type toid_t; do not use with esballoc(D3str).
canput(D3str)	Use bcanput(D3str) to test specific priority band; also see usage restrictions on manual page.
copyb(D3str)	The memory for the data buffer should not be assumed to be physically contiguous.
copymsg(D3str)	The memory for the data buffer should not be assumed to be physically contiguous.
datamsg(D3str)	Implemented as a function rather than as a macro.
enableok(D3str)	Implemented as a function rather than as a macro; also see usage restrictions on manual page.
esballoc(D3str)	The third argument, fr_rtnp, is now of type frtn_t *; also see usage restrictions on manual page.
flushband(D3str)	See usage restrictions on manual page.
flushq(D3str)	Use flushband(D3str) to flush specific priority band; also see usage restrictions on manual page.
getadmin(D3str)	This function is obsolete.
getmid(D3str)	This function is obsolete.

getq(D3str)	See usage restrictions on manual page.
insq(D3str)	See usage restrictions on manual page.
MPSTR_QLOCK(D3str)	This function is obsolete.
MPSTR_QRELE(D3str)	This function is obsolete.
MPSTR_STPLOCK(D3str)	This function is obsolete.
MPSTR_STPRELE(D3str)	This function is obsolete.
noenable(D3str)	Implemented as a function rather than as a macro; also see usage restrictions on manual page.
OTHERQ(D3str)	Implemented as a function rather than as a macro.
pullupmsg(D3str)	Not MP-safe; replaced by msgpullup(D3str).
put(D3str)	Provides an MP-safe, DDI-conforming equivalent of a direct call to the put(D2str) entry point.
putbq(D3str)	See usage restrictions on manual page.
putctl(D3str)	See usage restrictions on manual page.
putctl1(D3str)	See usage restrictions on manual page.
putnext(D3str)	Implemented as a function rather than as a macro; also see usage restrictions on manual page.
putq(D3str)	See usage restrictions on manual page.

qenable(D3str)	See usage restrictions on manual page.
qreply(D3str)	See usage restrictions on manual page.
qsize(D3str)	See usage restrictions on manual page.
RD(D3str)	Implemented as a function rather than as a macro.
rmvq(D3str)	See usage restrictions on manual page.
SAMESTR(D3str)	See usage restrictions on manual page.
strqget(D3str)	See usage restrictions on manual page.
strqset(D3str)	See usage restrictions on manual page.
testb(D3str)	This function is obsolete.
unbufcall(D3str)	This function now takes a single argument, id, of type toid_t; also see usage restrictions on manual page.
WR(D3str)	Implemented as a function rather than as a macro.