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From: Philippe Gerum <rpm@xenomai.org>
To: yo sang <stlfatboy@hotmail.com>
Cc: "xenomai@lists.linux.dev" <xenomai@lists.linux.dev>
Subject: Re: data modified by second NRT write with same memory location
Date: Tue, 01 Aug 2023 19:29:27 +0200
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yo sang <stlfatboy@hotmail.com> writes:

> Hi,
>
> 	I was playing with xddp recently, and found a strange situation.
> 	I modified official example xddp-echo to test my case:
>
> 	Main()
> 		*   =3D>  get socket=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
>  		*   =3D>  bind socket to port 0=20=20=20=20
> 		*   =3D>  open /dev/rtp0=20=20=20=20
>
> 		*	=3D>  create data buf with =E2=80=9Cfirst=E2=80=9D=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20
>  		*   =3D>  write buf to RT domain via write()=20=20=20=20
> 		* 	=3D>  modify data buf to =E2=80=9Csecond=E2=80=9D
> =E3=80=80=E3=80=80	*   =3D>  write buf to RT domain via write()=20=20=20
> =E3=80=80=E3=80=80
> 	* Start realtime_thread-------------------------------------->----------=
+=20=20=20=20=20=20=20=20
> =E3=80=80=E3=80=80	*   =3D>  read from NRT domain via recvfrom()=20=20=20=
=20=20
> =E3=80=80=E3=80=80	*	=3D>  print output: =E2=80=9Csecond"
>  		*   =3D>  read from NRT domain via recvfrom()=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20
> =E3=80=80		*	=3D>  print output: =E2=80=9Csecond=E2=80=9D=20=20=20=20=20=
=20=20
> =E3=80=80
> =E3=80=80If I write twice with same data location, the RT-end will receiv=
e =E2=80=9Csecond=E2=80=9D twice.
> =E3=80=80
> =E3=80=80Any comments?
> =E3=80=80Thanks
>
>=20=20=20=20=20=20=20=20=20=20=20=20=20=20

Please send the shortest possible piece of code illustrating the issue.

--=20
Philippe.