[Buildroot] 2022.02.1: read-only file system

[Buildroot] 2022.02.1: read-only file system

[Zvi Vered]

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Hello,

I'm using buildroot 2022.02.1 under x86 embedded SBC.
The root file system is located on the on-board disk.
The boot argument contains 'ro' (checked with /proc/cmdline after login)
but the disk is not read-only.

When I used the same boot args with busybox, it worked fine.
Of course with busybox I had to tailor all other mandatory files and
directories.

I need read-only rootfs to defend this embedded system in case of
power-down / cold reset.

Beyond the default configuration, the rootfs also contains ntp client,
httpd, pci tools.

Thank you,
Zvika

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Re: [Buildroot] 2022.02.1: read-only file system

[Arnout Vandecappelle]

On 11/09/2022 19:58, Zvi Vered wrote:
> Hello,
> 
> I'm using buildroot 2022.02.1 under x86 embedded SBC.
> The root file system is located on the on-board disk.
> The boot argument contains 'ro' (checked with /proc/cmdline after login) but the 
> disk is not read-only.

  There is a buildroot config option BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW which 
defaults to enabled. It will remount the rootfs to read-write as part of 
processing /etc/fstab. So you should probably turn that option off. Note that if 
you use systemd, you'll need to do a clean rebuild before the option is taken 
into account.


> When I used the same boot args with busybox, it worked fine.
> Of course with busybox I had to tailor all other mandatory files and directories.
> 
> I need read-only rootfs to defend this embedded system in case of power-down / 
> cold reset.

  Perhaps you're better off then to use an actual readonly filesystem, like 
erofs or squashfs? You have to make sure the corresponding kernel options are 
enabled, of course.

  Regards,
  Arnout

> 
> Beyond the default configuration, the rootfs also contains ntp client, httpd, 
> pci tools.
> 
> Thank you,
> Zvika
> 
> 
> 
> _______________________________________________
> buildroot mailing list
> buildroot@buildroot.org
> https://lists.buildroot.org/mailman/listinfo/buildroot
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Re: [Buildroot] 2022.02.1: read-only file system

[Zvi Vered]

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Hi Arnout,

Thank you very much !

Best regards,
Zvika

On Sat, Sep 17, 2022 at 11:05 PM Arnout Vandecappelle <arnout@mind.be>
wrote:

>
>
> On 11/09/2022 19:58, Zvi Vered wrote:
> > Hello,
> >
> > I'm using buildroot 2022.02.1 under x86 embedded SBC.
> > The root file system is located on the on-board disk.
> > The boot argument contains 'ro' (checked with /proc/cmdline after login)
> but the
> > disk is not read-only.
>
>   There is a buildroot config option BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW
> which
> defaults to enabled. It will remount the rootfs to read-write as part of
> processing /etc/fstab. So you should probably turn that option off. Note
> that if
> you use systemd, you'll need to do a clean rebuild before the option is
> taken
> into account.
>
>
> > When I used the same boot args with busybox, it worked fine.
> > Of course with busybox I had to tailor all other mandatory files and
> directories.
> >
> > I need read-only rootfs to defend this embedded system in case of
> power-down /
> > cold reset.
>
>   Perhaps you're better off then to use an actual readonly filesystem,
> like
> erofs or squashfs? You have to make sure the corresponding kernel options
> are
> enabled, of course.
>
>   Regards,
>   Arnout
>
> >
> > Beyond the default configuration, the rootfs also contains ntp client,
> httpd,
> > pci tools.
> >
> > Thank you,
> > Zvika
> >
> >
> >
> > _______________________________________________
> > buildroot mailing list
> > buildroot@buildroot.org
> > https://lists.buildroot.org/mailman/listinfo/buildroot
>

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