NiLFS support on Pinebook

NiLFS support on Pinebook

[Reinoud Zandijk]

Dear folks, dear Ryusuke,

I am trying to use NiLFS2 on my Pinebook that identifies itself as GNU/Linux
on aarch64. It allows me to install nilfs-tools wich seem to work fine but
when i mount a partition it gives the error "mount.nilfs2: cannot find or load
nilfs2 filesystem". Does this mean the linux kernel has no nilfs2 module
shipped with it, but only the tools?

How can I install the nilfs2 filesystem? Or is that up to the distribution and
out of my control?

With regards,
Reinoud

Re: NiLFS support on Pinebook

[Ryusuke Konishi]

Hi Reinoud,

> when i mount a partition it gives the error "mount.nilfs2: cannot find or load
> nilfs2 filesystem". Does this mean the linux kernel has no nilfs2 module
> shipped with it, but only the tools?

We see this message if nilfs2 kernel module (nilfs2.ko) doesn't exists in
/lib/modules/$(uname -r)/... .

Some distros don't have nilfs2 module (e.g. RHEL/CentOS), and some
need an extra package like kernel-modules-extra (e.g. Fedora).

I don't know that is there in the Pinebook.

Regards,
Ryusuke Konishi

On Wed, 26 Feb 2020 11:22:35 +0100, Reinoud Zandijk <reinoud-qavaossjCcEdnm+yROfE0A@public.gmane.org> wrote:
> Dear folks, dear Ryusuke,
> 
> I am trying to use NiLFS2 on my Pinebook that identifies itself as GNU/Linux
> on aarch64. It allows me to install nilfs-tools wich seem to work fine but
> when i mount a partition it gives the error "mount.nilfs2: cannot find or load
> nilfs2 filesystem". Does this mean the linux kernel has no nilfs2 module
> shipped with it, but only the tools?
> 
> How can I install the nilfs2 filesystem? Or is that up to the distribution and
> out of my control?
> 
> With regards,
> Reinoud
> 

Qemu (Re: NiLFS support on Pinebook)

[Reinoud Zandijk]

On Thu, Feb 27, 2020 at 12:14:57AM +0900, Ryusuke Konishi wrote:
> Hi Reinoud,
> 
> > when i mount a partition it gives the error "mount.nilfs2: cannot find or load
> > nilfs2 filesystem". Does this mean the linux kernel has no nilfs2 module
> > shipped with it, but only the tools?
> 
> We see this message if nilfs2 kernel module (nilfs2.ko) doesn't exists in
> /lib/modules/$(uname -r)/... .
> 
> Some distros don't have nilfs2 module (e.g. RHEL/CentOS), and some
> need an extra package like kernel-modules-extra (e.g. Fedora).
> 
> I don't know that is there in the Pinebook.

Problem with pinebook is that there are distro's around to test but they seem
to like the 3.10 kernel too much and update all but the kernel. The linux
headers they ship are for 4.x and 5.x so no use for compiling the kernel
module itself.

Can you recommend a lightweigth linux distro with nilfs support that runs fast
in `unaided' Qemu?  I.e. with only the `tcg' acceleration and with no
graphics?

Thanks in advance,
Reinoud

Re: Qemu (Re: NiLFS support on Pinebook)

[Reinoud Zandijk]

Hi Ryusuke,

On Fri, Feb 28, 2020 at 11:55:03AM +0100, Reinoud Zandijk wrote:
> Can you recommend a lightweigth linux distro with nilfs support that runs fast
> in `unaided' Qemu?  I.e. with only the `tcg' acceleration and with no
> graphics?

I've settled for a Debian without graphics and it works quite well AND it has
NiLFS2 support!

Testing it on one of my older test NiLFS2 images I had around it paniced when
I did this:

qemu-system-x86_64 -drive file=root.debian.fs,format=raw -accel
  tcg,thread=multi -smp cpus=4 -m 4096 -drive
  file=/usr/tmp/nilfs.4g.img,format=raw
....
    mount.nilfs2 /dev/sdb1 /mnt
    touch /mnt/UDF
wait a second or two
    CRASH

Note that /mnt/UDF exists and is a directory. It gives a NULL pointer
dereference at 0xa8
Call trace:
    __test_set_page_writeback+0x38c/0x3f0
    nilfs_segctor_do_construct+0x190f
    nilfs_segctor_construct+0x1f5
    nilfs_segctor_thread+0x127
....
RIP: 0010:percpu_counter_add_batch+0x04
....

Do you like to receive a copy of this image? It used to work fine and should
only be touched by your NiLFS code.

With regards,
Reinoud