kmem_zalloc(D3)

NAME
     kmem_zalloc - allocate and clear space from kernel free memory

SYNOPSIS
     #include <sys/types.h>
     #include <sys/kmem.h>
     #include <sys/ddi.h>
     void *kmem_zalloc(size_t size, int flag);

   Arguments
     size      Number of bytes to allocate.

     flag      Specifies whether the caller is willing to sleep waiting for
               memory, also other flags accepted by kmem_alloc.

DESCRIPTION
     kmem_zalloc allocates size bytes of kernel memory, clears the memory by
     filling it with zeros, and returns a pointer to the allocated memory.  If
     flag is set to KM_SLEEP, the caller will sleep if necessary until the
     specified amount of memory is available.  If flag is set to KM_NOSLEEP,
     the caller will not sleep, but kmem_zalloc will return NULL if the
     specified amount of memory is not immediately available.

   Return Values
     Upon successful completion, kmem_zalloc returns a pointer to the
     allocated memory.  If KM_NOSLEEP is specified and sufficient memory is
     not immediately available, kmem_zalloc returns a NULL pointer.  If size
     is set to 0, kmem_zalloc returns NULL regardless of the value of flag.

USAGE
     Kernel memory is a limited resource and should be used judiciously.
     Memory allocated using kmem_zalloc should be freed as soon as possible.
     Drivers should not use local freelists for memory or similar schemes that
     cause the memory to be held for longer than necessary.

     Since holding memory allocated using kmem_zalloc for extended periods of
     time (e.g allocating memory at system startup and never freeing it) can
     have an adverse effect on overall memory usage and system performance,
     memory needed for such extended periods should be statically allocated
     whenever possible.

     The address returned by a successful call to kmem_zalloc is word-aligned.

   Level
     Initialization or Base if flag is set to KM_SLEEP.

     Initialization, Base or Interrupt if flag is set to KM_NOSLEEP.

   Synchronization Constraints
     May sleep if flag is set to KM_SLEEP.
     Driver-defined basic locks, read/write locks, and sleep locks may be held
     across calls to this function if flag is KM_NOSLEEP, but may not be held
     if flag is KM_SLEEP.

     Driver-defined sleep locks may be held across calls to this function
     regardless of the value of flag.

REFERENCES
     kmem_alloc(D3), kmem_free(D3)