posix_memalign,  aligned_alloc,  memalign,  valloc,  pvalloc - allocate
   aligned memory


   #include <stdlib.h>

   int posix_memalign(void **memptr, size_t alignment, size_t size);
   void *aligned_alloc(size_t alignment, size_t size);
   void *valloc(size_t size);

   #include <malloc.h>

   void *memalign(size_t alignment, size_t size);
   void *pvalloc(size_t size);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

   posix_memalign(): _POSIX_C_SOURCE >= 200112L

   aligned_alloc(): _ISOC11_SOURCE

       Since glibc 2.12:
           (_XOPEN_SOURCE >= 500) && !(_POSIX_C_SOURCE >= 200112L)
               || /* Glibc since 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
       Before glibc 2.12:
           _BSD_SOURCE || _XOPEN_SOURCE >= 500
           (The (nonstandard) header  file  <malloc.h>  also  exposes  the
           declaration of valloc(); no feature test macros are required.)


   The  function  posix_memalign()  allocates  size  bytes  and places the
   address of the  allocated  memory  in  *memptr.   The  address  of  the
   allocated memory will be a multiple of alignment, which must be a power
   of two and a multiple of sizeof(void *).  If size is 0, then the  value
   placed  in  *memptr  is either NULL, or a unique pointer value that can
   later be successfully passed to free(3).

   The obsolete function memalign() allocates size  bytes  and  returns  a
   pointer to the allocated memory.  The memory address will be a multiple
   of alignment, which must be a power of two.

   The function aligned_alloc() is the same as memalign(), except for  the
   added restriction that size should be a multiple of alignment.

   The  obsolete  function  valloc()  allocates  size  bytes and returns a
   pointer to the allocated memory.  The memory address will be a multiple
   of      the      page      size.       It      is     equivalent     to

   The obsolete function pvalloc() is similar to valloc(), but rounds  the
   size of the allocation up to the next multiple of the system page size.

   For all of these functions, the memory is not zeroed.


   aligned_alloc(),  memalign(),  valloc(), and pvalloc() return a pointer
   to the allocated memory, or NULL if the request fails.

   posix_memalign() returns zero on success, or one of  the  error  values
   listed  in the next section on failure.  The value of errno is not set.
   On Linux (and other systems), posix_memalign() does not  modify  memptr
   on  failure.   A  requirement  standardizing this behavior was added in


   EINVAL The alignment argument was not a power of  two,  or  was  not  a
          multiple of sizeof(void *).

   ENOMEM There was insufficient memory to fulfill the allocation request.


   The  functions  memalign(), valloc(), and pvalloc() have been available
   in all Linux libc libraries.

   The function aligned_alloc() was added to glibc in version 2.16.

   The function posix_memalign() is available since glibc 2.1.91.


   For  an  explanation  of  the  terms  used   in   this   section,   see

   │InterfaceAttributeValue          │
   │aligned_alloc(), │ Thread safety │ MT-Safe        │
   │memalign(),      │               │                │
   │posix_memalign() │               │                │
   │valloc(),        │ Thread safety │ MT-Unsafe init │
   │pvalloc()        │               │                │


   The  function  valloc()  appeared in 3.0BSD.  It is documented as being
   obsolete in 4.3BSD, and as legacy in SUSv2.   It  does  not  appear  in

   The function pvalloc() is a GNU extension.

   The function memalign() appears in SunOS 4.1.3 but not in 4.4BSD.

   The  function  posix_memalign() comes from POSIX.1d and is specified in
   POSIX.1-2001 and POSIX.1-2008.

   The function aligned_alloc() is specified in the C11 standard.

   Everybody agrees that posix_memalign() is declared in <stdlib.h>.

   On some  systems  memalign()  is  declared  in  <stdlib.h>  instead  of

   According  to  SUSv2,  valloc() is declared in <stdlib.h>.  Libc4,5 and
   glibc declare it in <malloc.h>, and  also  in  <stdlib.h>  if  suitable
   feature test macros are defined (see above).


   On  many  systems  there  are  alignment  restrictions, for example, on
   buffers  used  for  direct  block  device  I/O.   POSIX  specifies  the
   pathconf(path,_PC_REC_XFER_ALIGN)  call  that  tells  what alignment is
   needed.  Now one can use posix_memalign() to satisfy this requirement.

   posix_memalign()  verifies  that  alignment  matches  the  requirements
   detailed  above.   memalign() may not check that the alignment argument
   is correct.

   POSIX requires that memory obtained from posix_memalign() can be  freed
   using free(3).  Some systems provide no way to reclaim memory allocated
   with memalign() or valloc() (because one can pass  to  free(3)  only  a
   pointer  obtained  from malloc(3), while, for example, memalign() would
   call  malloc(3)  and  then  align  the  obtained  value).   The   glibc
   implementation allows memory obtained from any of these functions to be
   reclaimed with free(3).

   The glibc malloc(3) always returns 8-byte aligned memory addresses,  so
   these functions are needed only if you require larger alignment values.


   brk(2), getpagesize(2), free(3), malloc(3)


   This  page  is  part of release 4.09 of the Linux man-pages project.  A
   description of the project, information about reporting bugs,  and  the
   latest     version     of     this    page,    can    be    found    at

More Linux Commands

gnutls_x509_trust_list_verify_named_crt(3) - API function...
This function will try to find a matching named certificate. If a match is found the certificate is considered valid. In addition to that this function will als

Tcl_UniCharIsAlpha(3) - routines for classification of Tcl_U
All of the routines described examine Tcl_UniChars and return a boolean value. A non-zero return value means that the character does belong to the character cla

XWriteBitmapFile(3) - manipulate bitmaps - Linux man page...
The XReadBitmapFile function reads in a file containing a bitmap. The file is parsed in the encoding of the current locale. The ability to read other than the s

rmdir(1) - remove empty directories - Linux manual page.....
Remove the DIRECTORY(ies), if they are empty. --ignore-fail-on-non-empty ignore each failure that is solely because a directory is non-empty -p, --parents remov

isupper(3) - character classification routines (Man Page)...
These functions check whether c, which must have the value of an unsigned char or EOF, falls into a certain character class according to the specified locale. T

pnmtopclxl(1) - convert a PNM image to an HP LaserJet PCL XL
This program is part of Netpbm(1) pnmtopclxl reads one or more PNM input streams, each containing one or more PNM images, and generates a sequence of output pag

getutmp(3) - copy utmp structure to utmpx, and vice versa...
The getutmp() function copies the fields of the utmpx structure pointed to by ux to the corresponding fields of the utmp structure pointed to by u. The getutmpx

numastat(8) - Print statistics about NUMA memory allocation
numastat with no command options or arguments at all, displays per-node NUMA hit and miss system statistics from the kernel memory allocator. This default numas

glTexCoord1fv(3gl) - set the current texture coordinates....
glTexCoord specifies texture coordinates in one, two, three, or four dimensions. glTexCoord1 sets the current texture coordinates to (s, 0, 0, 1); a call to glT

Tk_GetMMFromObj(3) - translate between strings and screen un
These procedures take as argument a specification of distance on the screen (objPtr or string) and compute the corresponding distance either in integer pixels o

ps2ascii(1) - Ghostscript translator from PostScript or PDF
ps2ascii uses gs(1) to extract ASCII text from PostScript(tm) or Adobe Portable Document Format (PDF) files. If no files are specified on the command line, gs r

timerfd_gettime(2) - timers that notify via file descriptors
These system calls create and operate on a timer that delivers timer expiration notifications via a file descriptor. They provide an alternative to the use of s

We can't live, work or learn in freedom unless the software we use is free.