Arch Linux

aif has no "Set Filesystems Mountpoints" step. you must be talking about the old installer.
though aif also lacks the feature you request.

What would be the purpose of this?

well, I've tried aif onloy once few days ago. I don't remember how it is exactly.

I basicaly set my /tmp and /var/tmp to be in RAM through tmpfs. it would be nice to be able to set this directly from the installer.
in the old installer, there would be a "tmpfs" entry on the page giving choice between all the available partitions.
choosing this entry would only ask for the mount point as it is the only thing to set.
in fact, there would always be a "tmpfs" entry available when we have to choose a partition.

I ask this feature because it seems to me that it should be quite easy to implement.

Yeah it's doable.. Not easy but doable.
I never used it myself but here is how I see it (please comment):
the backend/file format in aif has a notion of blockdevices on which you can put one or more (eg for an lvm volume group) filesystems.
The way it works is you choose a block device, and then you choose and configure one or more filesystems to put on top of it (the choices being limited by the type of blockdevice).
So I would just add a "blockdevice" ram and allow users to define one or more tmpfs'es on it, similar to how one puts multiple logical volumes in a volume group.
I would allow users to specify a size and mountpoint, but that's pretty much all I would let them customize. for further options they have to edit fstab themselves.

I've quickly run aif to remember how it is.
the idea of a ram "blockdevice" similar to the volume group blockdevice is exactly what I mean.

Allright then...It will be in aif..someday :)

btw: patches welcome

I think this can be closed now. Now by default /tmp is tmpfs in fstab, like other mountpoints.