Re: 2.3.51 -- I am still seeing the"shmget: shm filesystem not mounted" error

From: Christoph Rohland (hans-christoph.rohland@sap.com)
Date: Mon Mar 13 2000 - 04:14:08 EST


Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

> > Just as well. Some ancient X shm code I just looked at waits for
> > a confirmation event back from X before doing IPC_RMID, so I guess
> > this behaviour of not allowing shmat after IPC_RMID was already
> > the case for a certain "SunOS" some years ago.

HPUX, Solaris, True64, AIX and Reliant UNIX have the same behaviour.

> > As it should be.
>
> I'd disagree. The remove and attach technique is very very commonly
> used by other applications in order to ensure the segment is deleted
> if a program crashed - directly analogous to open/unlink/read.
>
> Gimp wont be the only thing that breaks. So the old behaviour needs
> to work at least for SYS5 IPC, what posix ipc does is another matter

No Linux is the only *NIX I know which did it this way (I do not have
any *BSD here). So all these programs are not portable?

I had some discussion with Al Viro about that issue, because in the
old Linux way a shm segment is something like a globally open file
descriptor and in the new behaviour it is simply a temporary file. I
first wanted to invent something along the open fd think case but Al
objected and I am convinced that he was right.

Greetings
                Christoph

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