diff -up hdf-4.2.15/hdf/src/hconv.h.aarch64 hdf-4.2.15/hdf/src/hconv.h
--- hdf-4.2.15/hdf/src/hconv.h.aarch64	2020-04-30 21:16:25.325499508 -0600
+++ hdf-4.2.15/hdf/src/hconv.h	2020-04-30 21:16:25.338499580 -0600
@@ -59,7 +59,7 @@
 /* CONSTANT DEFINITIONS                                                      */
 /*****************************************************************************/
 /* Generally Big-Endian machines */
-#if !defined(INTEL86) && !defined(MIPSEL) && !defined(DEC_ALPHA) && !defined(I860) && !defined(SUN386) && !(defined(__ia64) && !(defined(hpux) || defined(__hpux))) && !defined(__x86_64__) && !defined(__arm__)
+#if !defined(INTEL86) && !defined(MIPSEL) && !defined(DEC_ALPHA) && !defined(I860) && !defined(SUN386) && !(defined(__ia64) && !(defined(hpux) || defined(__hpux))) && !defined(__x86_64__) && !defined(__arm__) && !defined(__AARCH64EL__)
 #       define UI8_IN     DFKnb1b   /* Unsigned Integer, 8 bits */
 #       define UI8_OUT    DFKnb1b
 #       define SI16_IN    DFKnb2b   /* S = Signed */
diff -up hdf-4.2.15/hdf/src/hdfi.h.aarch64 hdf-4.2.15/hdf/src/hdfi.h
--- hdf-4.2.15/hdf/src/hdfi.h.aarch64	2020-04-30 21:16:25.326499514 -0600
+++ hdf-4.2.15/hdf/src/hdfi.h	2020-04-30 21:16:25.340499591 -0600
@@ -79,6 +79,7 @@
 #define     DFMT_LINUXSPARC     0x1111
 #define     DFMT_LINUX390       0x1111
 #define     DFMT_LINUXARM       0x4441
+#define     DFMT_LINUXAARCH64   0x4441
 
 /* I/O library constants */
 #define UNIXUNBUFIO 1
@@ -1341,6 +1342,44 @@ typedef long              hdf_pint_t;
 
 #endif /* IA64 */
 
+/* Linux AArch64 */
+#if defined __aarch64__
+
+#ifdef GOT_MACHINE
+If you get an error on this line more than one machine type has been defined.
+Please check your Makefile.
+#endif
+#define GOT_MACHINE
+
+#include <sys/file.h>               /* for unbuffered i/o stuff */
+#include <sys/stat.h>
+#define DF_MT             DFMT_LINUXAARCH64
+typedef void              VOID;
+typedef void              *VOIDP;
+typedef char              *_fcd;
+typedef char              char8;
+typedef unsigned char     uchar8;
+typedef char              int8;
+typedef unsigned char     uint8;
+typedef short int         int16;
+typedef unsigned short int uint16;
+typedef int               int32;
+typedef unsigned int      uint32;
+typedef int               intn;
+typedef unsigned int      uintn;
+typedef int               intf;     /* size of INTEGERs in Fortran compiler */
+typedef float             float32;
+typedef double            float64;
+typedef long              hdf_pint_t;   /* an integer the same size as a pointer */
+#define FNAME_POST_UNDERSCORE
+#define _fcdtocp(desc) (desc)
+#ifdef  HAVE_FMPOOL
+#define FILELIB PAGEBUFIO  /* enable page buffering */
+#else
+#define FILELIB UNIXBUFIO
+#endif
+#endif /* Linux AArch64 */
+
 #ifndef GOT_MACHINE
 No machine type has been defined.  Your Makefile needs to have someing like
 -DSUN or -DUNICOS in order for the HDF internal structures to be defined
diff -up hdf-4.2.15/mfhdf/fortran/jackets.c.in.aarch64 hdf-4.2.15/mfhdf/fortran/jackets.c.in
--- hdf-4.2.15/mfhdf/fortran/jackets.c.in.aarch64	2020-04-30 21:16:25.318499470 -0600
+++ hdf-4.2.15/mfhdf/fortran/jackets.c.in	2020-04-30 21:20:28.346831868 -0600
@@ -34,7 +34,7 @@
 
 struct ncfils {            /* This will be a common block from Fortran */
     double dd;
-#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
     int ll;
 #else
     long ll;
@@ -65,7 +65,7 @@ struct ncfils {            /* This will
 
 struct ncfils {            /* This will be a common block from Fortran */
     double dd;
-#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
     int ll;
 #else
     long ll;
@@ -420,7 +420,7 @@ stoig(shorts, ints, dims, basis, ndims)
 }
 #endif /* FORTRAN_HAS_NO_SHORT */
 
-#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 /*
  * Convert multi-dimensional array of NCLONGs stored in ints to packed
  * array of longs, in malloc'ed space.  Returns pointer to longs or NULL
@@ -908,7 +908,7 @@ nncvpt1(cdfid, varid, indices, value, rc
     return;
     }                /* else */
 #endif                /* FORTRAN_HAS_NO_SHORT */
-#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 #ifdef HDF
     if ((nc_type) datatype == NC_LONG && handle->file_type!=HDF_FILE) {
     long          longs = *(int *)value;
@@ -1022,7 +1022,7 @@ nncvpt(cdfid, varid, start, count, value
     return;
     }                /* else */
 #endif                /* FORTRAN_HAS_NO_SHORT */
-#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 #ifdef HDF
     if ((nc_type) datatype == NC_LONG && handle->file_type!=HDF_FILE) {
     long *longs = itol (value, ncount, ndims);
@@ -1133,7 +1133,7 @@ nncvptg(cdfid, varid, start, count, stri
     tmpbasis    = nctypelen(NC_LONG);
     else
 #endif
-#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
     if (datatype == NC_LONG)
     tmpbasis    = sizeof(int);
     else
@@ -1190,7 +1190,7 @@ nncvptg(cdfid, varid, start, count, stri
     return;
     }                /* else */
 #endif                /* FORTRAN_HAS_NO_SHORT */
-#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 #ifdef HDF
     if ((nc_type) datatype == NC_LONG && handle->file_type!=HDF_FILE) {
     long *longs = itolg (value, ncount, nbasis, ndims);
@@ -1326,7 +1326,7 @@ nncvgt1(cdfid, varid, indices, value, rc
     return;
     }                /* else */
 #endif                /* FORTRAN_HAS_NO_SHORT */
-#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 #ifdef HDF
     if ((nc_type) datatype == NC_LONG && handle->file_type!=HDF_FILE) {
     long          longs;
@@ -1468,7 +1468,7 @@ nncvgt(cdfid, varid, start, count, value
     return;
     }                /* else */
 #endif                /* FORTRAN_HAS_NO_SHORT */
-#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 #ifdef HDF
     if ((nc_type) datatype == NC_LONG && handle->file_type!=HDF_FILE) {
     long iocount = dimprod (ncount, ndims);    /* product of dimensions */
@@ -1606,7 +1606,7 @@ nncvgtg(cdfid, varid, start, count, stri
     tmpbasis    = nctypelen(NC_LONG);
     else
 #endif
-#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
     if (datatype == NC_LONG)
     tmpbasis    = sizeof(int);
     else
@@ -1677,7 +1677,7 @@ nncvgtg(cdfid, varid, start, count, stri
     return;
     }                /* else */
 #endif                /* FORTRAN_HAS_NO_SHORT */
-#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 #ifdef HDF
     if ((nc_type) datatype == NC_LONG && handle->file_type!=HDF_FILE) {
     long iocount = dimprod (ncount, ndims);    /* product of dimensions */
@@ -1843,7 +1843,7 @@ nncapt(cdfid, varid, attname, datatype,
     return;
     }                /* else */
 #endif                /* FORTRAN_HAS_NO_SHORT */
-#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 #ifdef HDF
     if ((nc_type) *datatype == NC_LONG && handle->file_type!=HDF_FILE) {
     long *longs = itol (value, attlen, 1);
@@ -2008,7 +2008,7 @@ nncagt(cdfid, varid, attname, value, rco
     return;
     }                /* else */
 #endif                /* FORTRAN_HAS_NO_SHORT */
-#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if  defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 #ifdef HDF
     if ((nc_type) datatype == NC_LONG && handle->file_type!=HDF_FILE) {
 /* EIP  We need to use int buffer to read data in on the platforms where long is 8 bytes
diff -up hdf-4.2.15/mfhdf/libsrc/array.c.aarch64 hdf-4.2.15/mfhdf/libsrc/array.c
diff -up hdf-4.2.15/mfhdf/libsrc/cdf.c.aarch64 hdf-4.2.15/mfhdf/libsrc/cdf.c
diff -up hdf-4.2.15/mfhdf/libsrc/netcdf.h.in.aarch64 hdf-4.2.15/mfhdf/libsrc/netcdf.h.in
--- hdf-4.2.15/mfhdf/libsrc/netcdf.h.in.aarch64	2020-04-30 21:16:25.347499629 -0600
+++ hdf-4.2.15/mfhdf/libsrc/netcdf.h.in	2020-04-30 21:24:11.366838259 -0600
@@ -293,7 +293,7 @@ typedef double        ncdouble;
 /*
  * Variables/attributes of type NC_LONG should use the C type 'nclong'
  */
-#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 /*
  * LP64 (also known as 4/8/8) denotes long and pointer as 64 bit types.
  * http://www.unix.org/version2/whatsnew/lp64_wp.html
diff -up hdf-4.2.15/mfhdf/libsrc/putget.c.aarch64 hdf-4.2.15/mfhdf/libsrc/putget.c
--- hdf-4.2.15/mfhdf/libsrc/putget.c.aarch64	2020-04-30 21:16:25.349499640 -0600
+++ hdf-4.2.15/mfhdf/libsrc/putget.c	2020-04-30 21:21:11.344052951 -0600
@@ -665,7 +665,7 @@ Void *values ;
     case NC_SHORT :
         return( xdr_NCvshort(xdrs, (unsigned)rem/2, (short *)values) ) ;
     case NC_LONG :
-#if (_MIPS_SZLONG == 64) || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if (_MIPS_SZLONG == 64) || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
         return( xdr_int(xdrs, (nclong *)values) ) ;
 #else
         return( xdr_long(xdrs, (nclong *)values) ) ;
diff -up hdf-4.2.15/mfhdf/libsrc/xdrposix.c.aarch64 hdf-4.2.15/mfhdf/libsrc/xdrposix.c
--- hdf-4.2.15/mfhdf/libsrc/xdrposix.c.aarch64	2020-04-30 21:16:25.321499486 -0600
+++ hdf-4.2.15/mfhdf/libsrc/xdrposix.c	2020-04-30 21:23:48.397752506 -0600
@@ -262,7 +262,7 @@ int nbytes;
 
 static bool_t   xdrposix_getlong();
 static bool_t   xdrposix_putlong();
-#if (_MIPS_SZLONG == 64) || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if (_MIPS_SZLONG == 64) || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 static bool_t   xdrposix_getint();
 static bool_t   xdrposix_putint();
 #endif
@@ -276,7 +276,7 @@ static long *    xdrposix_inline();
 #if (defined __sun && defined _LP64)
 static rpc_inline_t *    xdrposix_inline();
 #else
-#if ((defined __x86_64__ ) && !(defined __sun && defined _LP64)) || defined __powerpc64__ || defined __s390x__
+#if ((defined __x86_64__ ) && !(defined __sun && defined _LP64)) || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 static int32_t *    xdrposix_inline();
 #else
 static netlong *    xdrposix_inline();
@@ -302,9 +302,9 @@ static struct xdr_ops   xdrposix_ops = {
     xdrposix_getpos,    /* get offset in the stream */
     xdrposix_setpos,    /* set offset in the stream */
     xdrposix_inline,    /* prime stream for inline macros */
-#if (defined __sun && defined _LP64) || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if (defined __sun && defined _LP64) || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
     xdrposix_destroy,   /* destroy stream */
-#if !(defined __x86_64__) && !(defined __powerpc64__) && !(defined __s390x__) || (defined  __sun && defined _LP64) /* i.e. we are on SUN/Intel in 64-bit mode */
+#if !(defined __x86_64__) && !(defined __powerpc64__) && !(defined __s390x__) && !(defined __aarch64__) || (defined  __sun && defined _LP64) /* i.e. we are on SUN/Intel in 64-bit mode */
     NULL,               /* no xdr_control function defined */
 #endif
     /* Solaris 64-bit (arch=v9 and arch=amd64) has 64 bits long and 32 bits int. */
@@ -560,7 +560,7 @@ static long *
 #if (defined __sun && defined _LP64)
 static rpc_inline_t *
 #else
-#if ((defined  __x86_64__) && !(defined __sun && defined _LP64)) || defined __powerpc64__ || defined __s390x__
+#if ((defined  __x86_64__) && !(defined __sun && defined _LP64)) || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 static int32_t *
 #else
 static netlong *
@@ -581,7 +581,7 @@ xdrposix_inline(xdrs, len)
     return (NULL);
 }
 
-#if (_MIPS_SZLONG == 64) || (defined __sun && defined _LP64) || defined AIX5L64  || defined __x86_64__ || defined __powerpc64__ || defined __s390x__
+#if (_MIPS_SZLONG == 64) || (defined __sun && defined _LP64) || defined AIX5L64  || defined __x86_64__ || defined __powerpc64__ || defined __s390x__ || defined __aarch64__
 
 static bool_t
 xdrposix_getint(xdrs, lp)
diff -up hdf-4.2.15/mfhdf/ncgen/ncgen.l.aarch64 hdf-4.2.15/mfhdf/ncgen/ncgen.l
--- hdf-4.2.15/mfhdf/ncgen/ncgen.l.aarch64	2020-04-30 21:16:25.376499789 -0600
+++ hdf-4.2.15/mfhdf/ncgen/ncgen.l	2020-04-30 21:17:29.876854089 -0600
@@ -113,7 +113,7 @@ FloatInf|Infinity|Inf    {    /* float m
             yyerror(errstr);
         }
 
-#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || __powerpc64__ || defined __s390x__
+#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || __powerpc64__ || defined __s390x__ || defined __aarch64__
         if (dd < INT_MIN  ||  dd > INT_MAX)
 #else
         if (dd < LONG_MIN  ||  dd > LONG_MAX)
diff -up hdf-4.2.15/mfhdf/ncgen/ncgenyy.c.aarch64 hdf-4.2.15/mfhdf/ncgen/ncgenyy.c
--- hdf-4.2.15/mfhdf/ncgen/ncgenyy.c.aarch64	2020-04-30 21:16:25.382499822 -0600
+++ hdf-4.2.15/mfhdf/ncgen/ncgenyy.c	2020-04-30 21:18:12.880090311 -0600
@@ -991,7 +991,7 @@ YY_RULE_SETUP
             yyerror(errstr);
         }
 
-#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || __powerpc64__ || __s390x__
+#if defined __alpha || (_MIPS_SZLONG == 64) || defined __ia64 || (defined __sun && defined _LP64) || defined AIX5L64 || defined __x86_64__ || __powerpc64__ || __s390x__ || defined __aarch64__
         if (dd < INT_MIN  ||  dd > INT_MAX)
 #else
         if (dd < LONG_MIN  ||  dd > LONG_MAX)