Re: [RFC PATCH] rootfs: Use tmpfs for rootfs even if root= is given

[Stefan Berger]

On 10/31/23 16:33, H. Peter Anvin wrote:
> On October 31, 2023 10:11:01 AM PDT, Stefan Berger <stefanb@xxxxxxxxxxxxx> wrote:
> > On 10/31/23 12:56, Greg Kroah-Hartman wrote:
> > > On Tue, Oct 31, 2023 at 11:44:17AM -0400, Stefan Berger wrote:
> > > > rootfs currently does not use tmpfs if the root= boot option is passed
> > > > even though the documentation about rootfs (added in 6e19eded3684) in
> > > > Documentation/filesystems/ramfs-rootfs-initramfs.rst states:
> > > >
> > > >     If CONFIG_TMPFS is enabled, rootfs will use tmpfs instead of ramfs by
> > > >     default.  To force ramfs, add "rootfstype=ramfs" to the kernel command
> > > >     line.
> > > At this point in time, is there even any difference between ramfs and
> > > tmpfs anymore?  Why would you want to choose one over the other here?
> >
> > CONFIG_TPMFS_XATTRS allows us to set xattrs, such as security.ima.
> >
> >     Stefan
> >
> > > thanks,
> > >
> > > greg k-h
> Why do we even keep ramfs as a standalone file system? To guarantee it cannot be swapped out? Does anyone actually use it?

Probably all machines that have root= on the boot command line use it...