O_DIRECT flag undefined

["Bahadir Balban" <bilgehan.balban@xxxxxxxxx>]

Hi,

I have two toolchains: arm-none-linux-gnueabi-2005q3 and
arm-linux-2004q3. In both, O_DIRECT flag is undefined if I want to
compile an application using open() with this flag.

In 2004q3 in arm-linux/include/bits/fcntl.h there's a define:
#ifdef __USE_GNU
# define O_DIRECTORY	040000	/* Must be a directory.	 */
# define O_NOFOLLOW	0100000	/* Do not follow links.	 */
# define O_DIRECT	0200000	/* Direct disk access.	*/
#endif

Why are they guarded with __USE_GNU? If I define O_DIRECT myself in
fcntl.h, then I get Invalid argument error at runtime.

I was unable to locate a similar header in 2005q3. How could I use
O_DIRECT in my application, preferably with 2004q3 toolchain? Is it an
unsupported flag?

Many thanks,
Bahadir