GETRBUF(9F)GETRBUF(9F)NAMEgetrbuf - get a raw buffer header
struct buf *getrbuf(int sleepflag);
Architecture independent level 1 (DDI/DKI).
Indicates whether driver should sleep for free space.
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 allo‐
cation. 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.
The getrbuf() function returns a pointer to the allocated buffer
header, or NULL if no space is available.
The getrbuf() function can be called from user, interrupt, or kernel
context. (Drivers must not allow getrbuf() to sleep if called from an
SEE ALSObioinit(9F), freerbuf(9F), kmem_alloc(9F), kmem_free(9F)
Writing Device Drivers
Jan 16, 2006 GETRBUF(9F)