--- b/include/Makefile	
+++ b/include/Makefile	
@@ -11,8 +11,8 @@ SUBDIR= arpa protocols rpcsvc rpc xlocale
 SUBDIR_PARALLEL=
 INCS=	a.out.h ar.h assert.h bitstring.h complex.h cpio.h _ctype.h ctype.h \
 	db.h \
-	dirent.h dlfcn.h elf.h elf-hints.h err.h fmtmsg.h fnmatch.h fstab.h \
-	fts.h ftw.h getopt.h glob.h grp.h \
+	dirent.h dlfcn.h elf.h elf-hints.h endian.h err.h fmtmsg.h fnmatch.h \
+	fstab.h fts.h ftw.h getopt.h glob.h grp.h \
 	ieeefp.h ifaddrs.h \
 	inttypes.h iso646.h kenv.h langinfo.h libgen.h limits.h link.h \
 	locale.h malloc.h malloc_np.h memory.h monetary.h mpool.h mqueue.h \
--- /dev/null	
+++ b/include/endian.h	
@@ -0,0 +1,56 @@ 
+/*-
+ * Copyright (c) 2021 M Warner Losh <imp@FreeBSD.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+/*
+ * A mostly Linux/glibc-compatible endian.h
+ */
+
+#ifndef _ENDIAN_H_
+#define _ENDIAN_H_
+
+/*
+ * FreeBSD's sys/endian.h is very close to the interface provided on Linux by
+ * glibc's endian.h. Linux doesn't define the hto* [bl]*toh macros when there's
+ * a strict name space. We request that the FreeBSD-specific
+ * [lb]e{16,32,64}{enc,dec} be omitted as well.
+ */
+#define __OMIT_ENDIAN_ENCODE_DECODE
+#include <sys/endian.h>
+
+/*
+ * The bswap* functions cause problems for some Linux code (like mesa), so
+ * remove them from the name space as well.  You need to include sys/endian.h
+ * directly if you want these (or the other FreeBSD-specific macros) to be
+ * visible.
+ */
+#undef bswap16
+#undef bswap32
+#undef bswap64
+
+/*
+ * glibc uses double underscore for these symbols. Define these unconditionally.
+ * The compiler defines __BYTE_ORDER__ these days, so we don't do anything
+ * with that since sys/endian.h defines _BYTE_ORDER based on it.
+ */
+#define __BIG_ENDIAN		_BIG_ENDIAN
+#define __BYTE_ORDER		_BYTE_ORDER
+#define __LITTLE_ENDIAN		_LITTLE_ENDIAN
+#define __PDP_ENDIAN		_PDP_ENDIAN
+
+/*
+ * FreeBSD's sys/endian.h and machine/endian.h doesn't define a separate
+ * byte order for floats. Use the host non-float byte order.
+ */
+#define __FLOAT_WORD_ORDER	_BYTE_ORDER
+
+/*
+ * We don't define BIG_ENDI, LITTLE_ENDI, HIGH_HALF and LOW_HALF macros that
+ * glibc's endian.h defines since those appear to be internal to internal to
+ * glibc. We also don't try to emulate the various helper macros that glibc
+ * uses to limit namespace visibility.
+ */
+
+#endif /* _ENDIAN_H_ */
--- b/sys/sys/endian.h	
+++ b/sys/sys/endian.h	
@@ -55,6 +55,7 @@ typedef	__uint64_t	uint64_t;
 #define	_UINT64_T_DECLARED
 #endif
 
+#if __BSD_VISIBLE
 /*
  * General byte order swapping functions.
  */
@@ -67,16 +68,16 @@ typedef	__uint64_t	uint64_t;
  * endian to host byte order functions as detailed in byteorder(9).
  */
 #if _BYTE_ORDER == _LITTLE_ENDIAN
-#define	htobe16(x)	bswap16((x))
-#define	htobe32(x)	bswap32((x))
-#define	htobe64(x)	bswap64((x))
+#define	htobe16(x)	__bswap16((x))
+#define	htobe32(x)	__bswap32((x))
+#define	htobe64(x)	__bswap64((x))
 #define	htole16(x)	((uint16_t)(x))
 #define	htole32(x)	((uint32_t)(x))
 #define	htole64(x)	((uint64_t)(x))
 
-#define	be16toh(x)	bswap16((x))
-#define	be32toh(x)	bswap32((x))
-#define	be64toh(x)	bswap64((x))
+#define	be16toh(x)	__bswap16((x))
+#define	be32toh(x)	__bswap32((x))
+#define	be64toh(x)	__bswap64((x))
 #define	le16toh(x)	((uint16_t)(x))
 #define	le32toh(x)	((uint32_t)(x))
 #define	le64toh(x)	((uint64_t)(x))
@@ -84,20 +85,20 @@ typedef	__uint64_t	uint64_t;
 #define	htobe16(x)	((uint16_t)(x))
 #define	htobe32(x)	((uint32_t)(x))
 #define	htobe64(x)	((uint64_t)(x))
-#define	htole16(x)	bswap16((x))
-#define	htole32(x)	bswap32((x))
-#define	htole64(x)	bswap64((x))
+#define	htole16(x)	__bswap16((x))
+#define	htole32(x)	__bswap32((x))
+#define	htole64(x)	__bswap64((x))
 
 #define	be16toh(x)	((uint16_t)(x))
 #define	be32toh(x)	((uint32_t)(x))
 #define	be64toh(x)	((uint64_t)(x))
-#define	le16toh(x)	bswap16((x))
-#define	le32toh(x)	bswap32((x))
-#define	le64toh(x)	bswap64((x))
+#define	le16toh(x)	__bswap16((x))
+#define	le32toh(x)	__bswap32((x))
+#define	le64toh(x)	__bswap64((x))
 #endif /* _BYTE_ORDER == _LITTLE_ENDIAN */
 
 /* Alignment-agnostic encode/decode bytestream to/from little/big endian. */
-
+#ifndef __OMIT_ENDIAN_ENCODE_DECODE
 static __inline uint16_t
 be16dec(const void *pp)
 {
@@ -203,5 +204,6 @@ le64enc(void *pp, uint64_t u)
 	le32enc(p, (uint32_t)(u & 0xffffffffU));
 	le32enc(p + 4, (uint32_t)(u >> 32));
 }
-
+#endif	/* __OMIT_ENDIAN_ENCODE_DECODE */
+#endif	/* __BSD_VISIBLE */
 #endif	/* _SYS_ENDIAN_H_ */