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'\" te .\" Copyright (c) 2001, Oracle and/or its affiliates. All rights reserved. .TH id32_alloc 9F "12 Dec 2001" "Oracle Solaris 11.4" "Kernel Functions" .SH NAME id32_alloc, id32_free, id32_lookup \- 32-bit driver ID management routines .SH SYNOPSIS .LP .nf #include <sys/ddi.h> #include <sys/id32.h> \fBuint32_t\fR \fBid32_alloc\fR(\fBvoid *\fR\fIptr\fR, \fBint\fR \fIflag\fR); .fi .LP .nf \fBvoid\fR \fBid32_free\fR(\fBuint32_t\fR \fItoken\fR); .fi .LP .nf \fBvoid *\fR\fBid32_lookup\fR(\fBuint32_t\fR \fItoken\fR); .fi .SH INTERFACE LEVEL .sp .LP Solaris architecture specific (Solaris DDI). .SH PARAMETERS .sp .ne 2 .mk .na \fB\fIptr\fR\fR .ad .RS 8n .rt any valid 32- or 64-bit pointer .RE .sp .ne 2 .mk .na \fB\fIflag\fR \fR .ad .RS 8n .rt determines whether caller can sleep for memory (see \fBkmem_alloc\fR(9F) for a description) .RE .SH DESCRIPTION .sp .LP These routines were originally developed so that device drivers could manage 64-bit pointers on devices that save space only for 32-bit pointers. .sp .LP Many device drivers need to pass a 32-bit value to the hardware when attempting I/O. Later, when that I/O completes, the only way the driver has to identify the request that generated that I/O is via a "token". When the I/O is initiated, the driver passes this token to the hardware. When the I/O completes the hardware passes back this 32-bit token. .sp .LP Before Solaris supported 64-bit pointers, device drivers just passed a raw 32-bit pointer to the hardware. When pointers grew to be 64 bits this was no longer possible. The \fBid32_*()\fR routines were created to help drivers translate between 64-bit pointers and a 32-bit token. .sp .LP Given a 32- or 64-bit pointer, the routine \fBid32_alloc()\fR allocates a 32-bit token, returning 0 if \fBKM_NOSLEEP\fR was specified and memory could not be allocated. The allocated token is passed back to \fBid32_lookup()\fR to obtain the original 32- or 64-bit pointer. .sp .LP The routine \fBid32_free()\fR is used to free an allocated token. Once \fBid32_free()\fR is called, the supplied token is no longer valid. .sp .LP Note that these routines have some degree of error checking. This is done so that an invalid token passed to \fBid32_lookup()\fR will not be accepted as valid. When \fBid32_lookup()\fR detects an invalid token it returns NULL. Calling routines should check for this return value so that they do not try to dereference a NULL pointer. .SH CONTEXT .sp .LP These functions can be called from user or interrupt context. The routine \fBid32_alloc()\fR should not be called from interrupt context when the \fBKM_SLEEP\fR flag is passed in. All other routines can be called from interrupt or kernel context. .SH SEE ALSO .sp .LP \fBkmem_alloc\fR(9F) .sp .LP \fIWriting Device Drivers in Oracle Solaris 11.4\fR