FreeBSD Device Drivers

Contiguous Physical Memory Management Routines

The FreeBSD kernel provides two functions for contiguous physical memory management: contigmalloc and contigfree. Ordinarily, you’ll never use these functions. They’re primarily for dealing with machine-dependent code and the occasional network driver.

#include <sys/types.h>
#include <sys/malloc.h>

void *
contigmalloc(unsigned long size, struct malloc_type *type, int flags,
    vm_paddr_t low, vm_paddr_t high, unsigned long alignment,
    unsigned long boundary);

void
contigfree(void *addr, unsigned long size, struct malloc_type *type);

The contigmalloc function allocates size bytes of contiguous physical memory. If size is 0, contigmalloc will panic. If successful, the allocation will reside between physical ...