kmem_zalloc(D3)kmem_zalloc(D3)NAMEkmem_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.
DESCRIPTIONkmem_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.
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kmem_zalloc(D3)kmem_zalloc(D3)
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.
REFERENCESkmem_alloc(D3), kmem_free(D3)
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