svcadm(1M)을 검색하려면 섹션에서 1M 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
kmem_free(9f)
kmem_alloc(9F) Kernel Functions kmem_alloc(9F)
NAME
kmem_alloc, kmem_zalloc, kmem_free - allocate kernel memory
SYNOPSIS
#include <sys/types.h>
#include <sys/kmem.h>
void *kmem_alloc(size_t size, int flag);
void *kmem_zalloc(size_t size, int flag);
void kmem_free(void*buf, size_t size);
INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI).
PARAMETERS
size Number of bytes to allocate.
flag Determines whether caller can sleep for memory. Possible flags
are KM_SLEEP to allow sleeping until memory is available, or
KM_NOSLEEP to return NULL immediately if memory is not avail‐
able.
buf Pointer to allocated memory.
DESCRIPTION
The kmem_alloc() function allocates size bytes of kernel memory and
returns a pointer to the allocated memory. The allocated memory is at
least double-word aligned, so it can hold any C data structure. No
greater alignment can be assumed. flag determines whether the caller
can sleep for memory. KM_SLEEP allocations may sleep but are guaranteed
to succeed. KM_NOSLEEP allocations are guaranteed not to sleep but may
fail (return NULL) if no memory is currently available. The initial
contents of memory allocated using kmem_alloc() are random garbage.
kmem_alloc should never be called (regardless of KM_SLEEP or KM_NOSLEEP
allocations) while holding a spin lock. Note that kmem_alloc can block
even when the KM_NOSLEEP flag is provided.
The kmem_zalloc() function is like kmem_alloc() but returns zero-filled
memory.
The kmem_free() function frees previously allocated kernel memory. The
buffer address and size must exactly match the original allocation.
Memory cannot be returned piecemeal.
RETURN VALUES
If successful, kmem_alloc() and kmem_zalloc() return a pointer to the
allocated memory. If KM_NOSLEEP is set and memory cannot be allocated
without sleeping, kmem_alloc() and kmem_zalloc() return NULL.
CONTEXT
The kmem_alloc() and kmem_zalloc() functions can be called from inter‐
rupt context only if the KM_NOSLEEP flag is set. They can be called
from user context with any valid flag. The kmem_free() function can be
called from from user, interrupt, or kernel context.
SEE ALSO
copyout(9F), freerbuf(9F), getrbuf(9F)
Writing Device Drivers in Oracle Solaris 11.4
WARNINGS
Memory allocated using kmem_alloc() is not paged. Available memory is
therefore limited by the total physical memory on the system. It is
also limited by the available kernel virtual address space, which is
often the more restrictive constraint on large-memory configurations.
Excessive use of kernel memory is likely to affect overall system per‐
formance. Overcommitment of kernel memory will cause the system to hang
or panic.
Misuse of the kernel memory allocator, such as writing past the end of
a buffer, using a buffer after freeing it, freeing a buffer twice, or
freeing a null or invalid pointer, will corrupt the kernel heap and may
cause the system to corrupt data or panic.
The initial contents of memory allocated using kmem_alloc() are random
garbage. This random garbage may include secure kernel data. Therefore,
uninitialized kernel memory should be handled carefully. For example,
never copyout(9F) a potentially uninitialized buffer.
NOTES
kmem_alloc(0, flag) always returns NULL. kmem_free(NULL, 0) is legal.
Oracle Solaris 11.4 24 Dec 2013 kmem_alloc(9F)