Re: Does /var/shm still need to be mounted?

From: Tigran Aivazian (
Date: Fri Jun 02 2000 - 17:10:56 EST

On 2 Jun 2000, H. Peter Anvin wrote:

> Followup to: <Pine.LNX.4.21.0006021321300.2581-100000@saturn.homenet>
> By author: Tigran Aivazian <>
> In newsgroup:
> >
> > did you look at kern_mount/umount interface that went into the kernel
> > recently? Things like shm and pipefs should (and already are) mounted
> > under artificially constructed root mountpoints like "pipe:" which are not
> > visible for namelookups coming from userspace. Ok, it is not the case for
> > shm currently (it is mounted on /) but perhaps it should be (i.e. the way
> > root dentry should be allocated as for pipefs using d_alloc() directly
> > instead of using generic d_alloc_root())?
> >
> > I cc'd Al Viro as I suspect he knows the answer to the above question.
> >
> No, shmfs actually needs a real path. Not for SysV IPC, but for POSIX
> IPC.

that is not an answer to the question I asked. If you read the sentence
that has the question mark (not the subject) you will see that I was
asking if the kern_mounted (and not the user-mounted) instance of shmfs
has to be mounted under "/" or can it be done like for pipefs under an
artificially constructed "shm:" like "pipe:"

For this reason I cc'd Al Viro also - not to ask him a question on POSIX
vs System V IPC but a question on root dentry allocation differences of
pipefs vs shmfs. (I cc'd him again)


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