Question regarding squashfs

Hi Robert,

I am using a BBB Rev A5C which only has 2 GB of emmc storage. In order to conserve the storage, I am thinking to use squashfs for my root file-system. The layout I am planning will be some thing like a /boot partition, / partition, and then another partition that will act as an overlay over squashfs. Also I am planning to have a option available so that I can enable a separate overlay for the /home in case a SD card is present.

I don’t exactly know the amount of changes required for this, but roughly I guess I have to customize the kernel and the initrd at the very least. Could you please comment on whether this kind of system is possible and if it will have any impact on performance of the system.

With Best Regards
viraniac

Gunjan Gupta <viraniac@gmail.com> [14-12-12 08:48]:

Hi Robert,

I am using a BBB Rev A5C which only has 2 GB of emmc storage. In order to
conserve the storage, I am thinking to use squashfs for my root
file-system. The layout I am planning will be some thing like a /boot
partition, / partition, and then another partition that will act as an
overlay over squashfs. Also I am planning to have a option available so
that I can enable a separate overlay for the /home in case a SD card is
present.

I don't exactly know the amount of changes required for this, but roughly I
guess I have to customize the kernel and the initrd at the very least.
Could you please comment on whether this kind of system is possible and if
it will have any impact on performance of the system.

With Best Regards
viraniac

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Hi Gunjan,

not exactly the answer to your question but maybe a way to keep
the rootfs small and speedy (no compression/decompression).

Warning! This needs more do-it-yourself-action and -compiling.

Instead of the usual Distros, which came which much stuff installed
to keep it easy and straigh forward for beginners try GENTOO.

Gentoo is source code based - which means you have to compile the
stuff you want (beside a rudimentary rootfs) yourself, which takes
time, especially on "small devices" like Beaglebone Black, Arietta.G25
etc.

The usual steps are:
Download a stage3 rootfs from here:
http://distfiles.gentoo.org/releases/arm/autobuilds/current-stage3-armv7a_hardfp/
and detar the stuff as root onto the second (rootfs) partition.
Install UBoot, uEnv.txt and zImage onto the first partition.

Do the basic Gentoo configuration steps as described here:
https://www.gentoo.org/doc/en/handbook/handbook-x86.xml

(start with chapter 8.)

This is for x86 systems, but on the level of application there is not
much difference to ARM.

After that you will have a very small system and you are free to only
install those things you want. Package dependencies are tracked by
the package manager (eix/emerge and the Gentooo ebuilds), so no
worry about that.

+ Pros: As said -- you can keep it small.
- Cons: Time needed for compiling the applications (especially valid in
  the beginning) and there is more to do "by hand" as with other
  distros...but this evolve into a "Pro" after some time...you will
  see :slight_smile:

HTH!

Best regards,
Meino

Well, Linux from scratch is not applicable only to Gentoo. This can pretty much be done with any distro.

https://wiki.debian.org/Debootstrap

Which I think is what Robert’s image_builder script uses. Not positive as I’ve not used it yet myself, but it would make sense. However, there is no need for that if not a requirement. As:

https://eewiki.net/display/linuxonarm/BeagleBone+Black

Exists, and if you use https://eewiki.net/display/linuxonarm/BeagleBone+Black#BeagleBoneBlack-RootFileSystem%28smallflash%29

We’re talking a ~70-75M working / bootable Debian image. It is a fairly minimal system, but a perfect base image for you to install exactly what you want / need.

Also, there were reports very early on that Sabayon Linux was run-able on the BBB as well. However that is a fork on Gentoo with purportedly a more “cutting edge” package repo. I have not personally touched Sabayon in years though . . .

Hi William,

I am currently using a custom image built with Robert’s Image Builder script. It’s a console image with all the things install that I need and the image size is about 800MB. Based on my experience with squashfs on x86 platform, I know if squashfs is used this can be brought down to 200 to 300 MB. Thats why I am willing to use squashfs.

I have searched on the forum and have found some posts regarding squashfs, but it doesn’t look like any one ever succeeded to built an image or atleast no one shared there success on the forum.

Could you comment about whether using squashfs willl be practical or not for BBB

Thanks & Regards
viraniac