init/do_mounts.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
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.
However, this currently does not work when root= is passed on the boot
command line since then saved_root_name contains a string and prevents
usage of tmpfs. Therefore, remove the check on saved_root_name to
enable tmpfs for rootfs.
Fixes: 6e19eded3684 ("initmpfs: use initramfs if rootfstype= or root= specified")
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Cc: "Milton D. Miller II" <mdmii@outlook.com>
Cc: Rob Landley <rob@landley.net>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jim Cromie <jim.cromie@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
---
init/do_mounts.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 5dfd30b13f48..6567cf5807ee 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -510,7 +510,7 @@ struct file_system_type rootfs_fs_type = {
void __init init_rootfs(void)
{
- if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
+ if (IS_ENABLED(CONFIG_TMPFS) &&
(!root_fs_names || strstr(root_fs_names, "tmpfs")))
is_tmpfs = true;
}
--
2.40.1On 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? thanks, greg k-h
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@landley.net/ Rob
On Wed, 2023-11-01 at 06:35 -0500, 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@landley.net/ Rob, the patch set wasn't upstreamed, but it certainly wasn't ignored. There were multiple comments. Can you at least re-post "[PATCH 5/5] fix rootfstype=tmpfs" after addressing the checkpatch.pl complaints? -- thanks, Mimi
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@landley.net/ Everyone, I now responded to Rob's patch over here: https://lkml.org/lkml/2023/11/1/333 > > Rob
On Wed, Nov 01, 2023 at 10:16:37AM -0400, Stefan Berger wrote: > > > 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@landley.net/ > > Everyone, > I now responded to Rob's patch over here: > https://lkml.org/lkml/2023/11/1/333 Note, we can't do anything with lkml.org links, they don't even work at times, please always use lore.kernel.org Also, one patch out of a longer series also will not work as we can't pick it up from there either. Can someone resend it, as a stand-alone patch, with the proper people cc:ed and then we can handle that. You all know this... thanks, greg k-h > > > > > > Rob
On Wed, 2023-11-01 at 15:28 +0100, Greg Kroah-Hartman wrote: > On Wed, Nov 01, 2023 at 10:16:37AM -0400, Stefan Berger wrote: > > > > > > 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@landley.net/ > > > > Everyone, > > I now responded to Rob's patch over here: > > https://lkml.org/lkml/2023/11/1/333 > > Note, we can't do anything with lkml.org links, they don't even work at > times, please always use lore.kernel.org > > Also, one patch out of a longer series also will not work as we can't > pick it up from there either. > > Can someone resend it, as a stand-alone patch, with the proper people > cc:ed and then we can handle that. You all know this... The initramfs@vger.kernel.org mailing list should be Cc'ed as well. -- thanks, Mimi
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@landley.net/
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
On 11/1/23 07:11, Stefan Berger wrote: > 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@landley.net/ > > 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... Regarding the "why ramfs" question, one bug report I periodically get is people using initramfs.cpio.gz that works on ramfs but fails to extract when they try tmpfs, and the reason is tmpfs defaults to size=50% of memory and their archive extracts to more than that. Since ramfs hasn't got a limit, it extracted and ran fine (generally a dedicated init app doing its IoT thing) and so far they've always gone back to ramfs as their fix. I vaguely recall I had some todo item to let them supply arguments so they could specify their own size= for initmpfs (ramfs doesn't take any so it hadn't been wired up last time I looked), but somewhere between https://lkml.org/lkml/2016/6/22/686 and https://lkml.iu.edu/hypermail/linux/kernel/2302.2/05597.html still being out of tree 7 years later I kind of lost interest... Rob
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