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

[Stefan Berger]

On 11/1/23 07:35, Rob Landley wrote:
> On 10/31/23 11:56, 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?
>
> I submitted a patch to fix this to the list multiple times, which got ignored as
> always. Most recently here:
>
> https://lore.kernel.org/lkml/8244c75f-445e-b15b-9dbf-266e7ca666e2@xxxxxxxxxxx/

I just tried it with your patch and the machine I am using this with 
(OpenBMC) uses the boot command line 'console=ttyS4,115200n8 
root=/dev/ram rw'. When I append rootfstype=tmpfs to this boot command 
line then it starts actually using tmpfs. So I think this would work for me.
I can add my Tested-by tag to the patch if this helps to get it merged. 
Ideally it would also propagate back with a Fixes tag...

   Stefan

> Rob