SVR5

kmem_alloc_phys(D3)

kmem_alloc_phys -- allocate DMA-addressable, driver-accessible memory

Synopsis

   #include <sys/types.h>
   #include <sys/ddi.h>
   
   void kmem_alloc_phys(size_t size, physreq_t preqp,
        paddr32_t paddrp, int flags);

Description

The kmem_alloc_phys( ) function allocates size bytes of physically-contiguous memory with the physical address alignment properties specified by the preqp structure and returns the base physical address of this memory in the array pointed to by the paddrp argument. The memory returned by kmem_alloc_phys( ) is always physically contiguous, even if the PREQ_PHYSCONTIG bit is not set.

Arguments

size

Number of bytes to allocate.

preqp

Pointer to a physreq(D4) structure. preqp->phys_dmasize must not be zero.

paddrp

Base physical address for the allocated memory. This can be an array of 32-bit numbers; the first element is the least-signficant 32 bits of the address, the next is the next 32 bits, and so forth. The number of array elements can be expressed as:

   (preqp->phys_dmasize + 31) / 32.

The value yielded is rounded.

flags

Valid values are:

0: Allocation can block to wait for resources.
KM_FAIL_OK: Return NULL if memory is not readily available, although the allocation may still block for a limited amount of time.

Return values

On success, kmem_alloc_phys( ) returns a pointer to the allocated memory and the base physical address (from the driver's point of view), in memory pointed to by the paddrp argument.

If flags is set to KM_FAIL_OK and memory is not available for the allocation, kmem_alloc_phys( ) returns NULL and does not allocate the memory.

Usage

DDI 8 restricts kmem_alloc_phys( ) allocations to the lower 4GB of memory. This is necessary because DDI 8 does not permit HBA drivers to specify a DMA width of 64 with a command width of 32.

Context and synchronization

User or blockable context.

Hardware applicability

All

Version applicability

ddi: 8, 8mp

Differences between versions

References

kmem_free(D3) msgscgth(D3str), scgth(D4), sdi_kmem_alloc_phys(D3sdi)

``Memory allocation'' in HDK Technical Reference