man/man9f/getrbuf.9f

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 GETRBUF 9F "Jan 27, 2015"
 NAME
getrbuf - get a raw buffer header
 SYNOPSIS

#include <sys/buf.h>
#include <sys/kmem.h>
#include <sys/ddi.h>


struct buf *getrbuf(int sleepflag);


 INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).
 PARAMETERS
sleepflag

Indicates whether driver should sleep for free space.


 DESCRIPTION

The getrbuf() function allocates the space for a buffer header to the
caller. It is used in cases where a block driver is performing raw (character
interface) I/O and needs to set up a buffer header that is not associated with
the buffer cache.

The getrbuf() function calls kmem_alloc(9F) to perform the memory
allocation. kmem_alloc() requires the information included in the
sleepflag argument. If sleepflag is set to KM_SLEEP, the
driver may sleep until the space is freed up. If sleepflag is set to
KM_NOSLEEP, the driver will not sleep. In either case, a pointer to the
allocated space is returned or NULL to indicate that no space was
available.
 RETURN VALUES

The getrbuf() function returns a pointer to the allocated buffer header,
or NULL if no space is available.
 CONTEXT

The getrbuf() function can be called from user, interrupt, or kernel
context. (Drivers must not allow getrbuf() to sleep if called from an
interrupt routine.)
 SEE ALSO

 bioinit (9F),  freerbuf (9F),  kmem_alloc (9F),  kmem_free (9F)
Writing Device Drivers