Architecture independent level 1 (DDI/DKI).

sleepflag

Indicates whether driver should sleep for free space.

getrbuf() 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.

getrbuf() 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.

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

getrbuf() can be called from user or interrupt context. (Drivers must not allow getrbuf() to sleep if called from an interrupt routine.)

bioinit(9F), freerbuf(9F), kmem_alloc(9F), kmem_free(9F)

Writing Device Drivers