Possibility of software installation on external storage outside of Pyra

[Borrubo]

Just a short question. I'm quite new to linux and the forum, so apologies in advance if this is a stupid question, or answered elsewere.
I read that it should be possible; or already is, to install software on to removable usb or sd cards. Is this done by a new packaging system? If so, does it work with apt or apt-get? And also if so, would it be possible to use this outside of the Pyra project? For example on some other linux handheld (pocketchip) with limited internal storage. You shouldn't be able to use the same repositories, because of different processor architectures, but the question in short, how much is the work on this solution usable on other hardware - architectures?
Thanks in advance

 

[slaeshjag]

There's three main ways to accomplish it. The first is to simply install software on an external media, add it to PATH and LDPATH, and just use it like that. The system package manager won't know anything about it, so there's that. The second is to move that part of the system (for example, the entire /usr directory). This means the majority of the space used by software is moved to external media, and the system package manager will make use of it. The downside is that removing the media will result in a horribly broken system.

The Pandora have a system (the PND system) which very much inspired the system I wrote for the Pyra (the DBP system) for putting applications and games on external media. Neither is seen by the system package manager, but both can support its own package manager. The DBP system has some integration to depend on packages installed with dpkg (and thus apt/aptitude). The advantage of those systems, is that removal of the removable storage is expected, and any tinkering done with the packages outside of the running system is just something they have to deal with. In both cases, the packages are a single file in the form of a mountable file system with some metadata. The DBP system does, unlike the PND system, automatically hook "installed" packages into PATH, and supports automatic file extension association (meaning a file type can automatically open with a "hot-pluggable" application. This has some obvious security implications that probably aren't acceptable on anything but hand-held single-user systems.

To answer the question: could it work on other handhelds like the pocket chip? Assuming the use-cases and general requirements are the same as the Pandora/Pyra, then yes.

The DBP system does have basic architecture differentiation support, but it's very coarse and probably requires work by someone smarter than me. It currently runs on both armhf and amd64. The code itself is portable enough that it should compile on anything linux with enough system resources to run it.

 

[Borrubo]

Thank you for the quick answer. I will try the first and third methode. If i get DBP to work on pocketchip, i will let you know. Don't expect much

 

[slaeshjag]

If you're running debian jessie or later, and have an aufs enabled kernel, it should Just Work™