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

[H. Peter Anvin]

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?