SVR5

kmem_zalloc_physreq(D3)

kmem_zalloc_physreq -- allocate and clear memory with specified physical properties

Synopsis

   #include <sys/types.h>
   #include <sys/kmem.h>
   #include <sys/ddi.h>
   
   void *kmem_zalloc_physreq(size_t size, physreq_t *preqp, int flag)

Description

kmem_zalloc_physreq allocates size bytes of memory with the physical address alignment and contiguity properties specified by preqp, and then clear the memory by filling it with zeros. If flag is set to KM_SLEEP, the caller will sleep, if necessary, until the memory with the specified properties is available. If flag is set to KM_NOSLEEP, the caller will not sleep, but kmem_zalloc_physreq will return NULL if suitable memory is not immediately available.

Arguments

size: Number of bytes to allocate.
preqp: Pointer to a physreq(D4) structure.
flag: Specifies whether the caller is willing to sleep waiting for memory.

Return values

Upon successful completion, kmem_zalloc_physreq returns a pointer to the allocated memory. If size is set to 0, kmem_zalloc_physreq returns NULL regardless of the value of flag.

Usage

The preqp argument points to a physreq structure, previously allocated by physreq_alloc(D3). This structure is used to define physical address alignment requirements.

Warnings

Drivers should call kmem_zalloc_physreq as early as possible if contiguous memory larger than one page is being requested, preferably during driver initialization. Due to randomization of the free page list, physically contiguous pages might not be available after the system has run at load for some time. This could cause kmem_zalloc_physreq to either fail (in the KM_NOSLEEP case) or possibly wait forever (in the KM_SLEEP case).

This routine should not be called during I/O transfers when contiguous memory larger than one page is being requested.

Context and synchronization

If flag is set to KM_NOSLEEP, non-blockable, initialization, or interrupt context.

If flag is set to KM_SLEEP, user context.

Hardware applicability

All

Version applicability

ddi: 6, 6mp, 7, 7mp, 7.1, 7.1mp, 8, 8mp

References

kmem_alloc(D3), kmem_alloc_physreq(D3), kmem_free(D3), kmem_zalloc(D3), physreq(D4) physreq_alloc(D3), physreq_prep(D3), strategy(D2)