Considering Convergence

What is Convergence

In 2013 Kyle Rankin (at the time Linux Journal columnist and CSO of Purism) wrote a Linux Journal article about Linux convergence [1] (which means using a phone and a dock to replace a desktop) featuring the Nokia N900 smart phone and a chroot environment on the Motorola Droid 4 Android phone. Both of them have very limited hardware even by the standards of the day and neither of which were systems I’d consider using all the time. None of the Android phones I used at that time were at all comparable to any sort of desktop system I’d want to use.

Hardware for Convergence – Comparing a Phone to a Laptop

The first hardware issue for convergence is docks and other accessories to attach a small computer to hardware designed for larger computers. Laptop docks have been around for decades and for decades I haven’t been using them because they have all been expensive and specific to a particular model of laptop. Having an expensive dock at home and an expensive dock at the office and then replacing them both when the laptop is replaced may work well for some people but wasn’t something I wanted to do. The USB-C interface supports data, power, and DisplayPort video over the same cable and now USB-C docks start at about $20 on eBay and dock functionality is built in to many new monitors. I can take a USB-C device to the office of any large company and know there’s a good chance that there will be a USB-C dock ready for me to use. The fact that USB-C is a standard feature for phones gives obvious potential for convergence.

The next issue is performance. The Passmark benchmark seems like a reasonable way to compare CPUs [2]. It may not be the best benchmark but it has an excellent set of published results for Intel and AMD CPUs. I ran that benchmark on my Librem5 [3] and got a result of 507 for the CPU score. At the end of 2017 I got a Thinkpad X301 [4] which rates 678 on Passmark. So the Librem5 has 3/4 the CPU power of a laptop that was OK for my use in 2018. Given that the X301 was about the minimum specs for a PC that I can use (for things other than serious compiles, running VMs, etc) the Librem 5 has 3/4 the CPU power, only 3G of RAM compared to 6G, and 32G of storage compared to 64G. Here is the Passmark page for my Librem5 [5]. As an aside my Libnrem5 is apparently 25% faster than the other results for the same CPU – did the Purism people do something to make their device faster than most?

For me the Librem5 would be at the very low end of what I would consider a usable desktop system. A friend’s N900 (like the one Kyle used) won’t complete the Passmark test apparently due to the “Extended Instructions (NEON)” test failing. But of the rest of the tests most of them gave a result that was well below 10% of the result from the Librem5 and only the “Compression” and “CPU Single Threaded” tests managed to exceed 1/4 the speed of the Librem5. One thing to note when considering the specs of phones vs desktop systems is that the MicroSD cards designed for use in dashcams and other continuous recording devices have TBW ratings that compare well to SSDs designed for use in PCs, so swap to a MicroSD card should work reasonably well and be significantly faster than the hard disks I was using for swap in 2013!

In 2013 I was using a Thinkpad T420 as my main system [6], it had 8G of RAM (the same as my current laptop) although I noted that 4G was slow but usable at the time. Basically it seems that the Librem5 was about the sort of hardware I could have used for convergence in 2013. But by today’s standards and with the need to drive 4K monitors etc it’s not that great.

The N900 hardware specs seem very similar to the Thinkpads I was using from 1998 to about 2003. However a device for convergence will usually do more things than a laptop (IE phone and camera functionality) and software had become significantly more bloated in 1998 to 2013 time period. A Linux desktop system performed reasonably with 32MB of RAM in 1998 but by 2013 even 2G was limiting.

Software Issues for Convergence

Jeremiah Foster (Director PureOS at Purism) wrote an interesting overview of some of the software issues of convergence [7]. One of the most obvious is that the best app design for a small screen is often very different from that for a large screen. Phone apps usually have a single window that shows a view of only one part of the data that is being worked on (EG an email program that shows a list of messages or the contents of a single message but not both). Desktop apps of any complexity will either have support for multiple windows for different data (EG two messages displayed in different windows) or a single window with multiple different types of data (EG message list and a single message). What we ideally want is all the important apps to support changing modes when the active display is changed to one of a different size/resolution. The Purism people are doing some really good work in this regard. But it is a large project that needs to involve a huge range of apps.

The next thing that needs to be addressed is the OS interface for managing apps and metadata. On a phone you swipe from one part of the screen to get a list of apps while on a desktop you will probably have a small section of a large monitor reserved for showing a window list. On a desktop you will typically have an app to manage a list of items copied to the clipboard while on Android and iOS there is AFAIK no standard way to do that (there is a selection of apps in the Google Play Store to do this sort of thing).

Purism has a blog post by Sebastian Krzyszkowiak about some of the development of the OS to make it work better for convergence and the status of getting it in Debian [8].

The limitations in phone hardware force changes to the software. Software needs to use less memory because phone RAM can’t be upgraded. The OS needs to be configured for low RAM use which includes technologies like the zram kernel memory compression feature.


When mobile phones first came out they were used for less secret data. Loss of a phone was annoying and expensive but not a security problem. Now phone theft for the purpose of gaining access to resources stored on the phone is becoming a known crime, here is a news report about a thief stealing credit cards and phones to receive the SMS notifications from banks [9]. We should expect that trend to continue, stealing mobile devices for ssh keys, management tools for cloud services, etc is something we should expect to happen.

A problem with mobile phones in current use is that they have one login used for all access from trivial things done in low security environments (EG paying for public transport) to sensitive things done in more secure environments (EG online banking and healthcare). Some applications take extra precautions for this EG the Android app I use for online banking requires authentication before performing any operations. The Samsung version of Android has a system called Knox for running a separate secured workspace [10]. I don’t think that the Knox approach would work well for a full Linux desktop environment, but something that provides some similar features would be a really good idea. Also running apps in containers as much as possible would be a good security feature, this is done by default in Android and desktop OSs could benefit from it.

The Linux desktop security model of logging in to a single account and getting access to everything has been outdated for a long time, probably ever since single-user Linux systems became popular. We need to change this for many reasons and convergence just makes it more urgent.


I have become convinced that convergence is the way of the future. It has the potential to make transporting computers easier, purchasing cheaper (buy just a phone and not buy desktop and laptop systems), and access to data more convenient. The Librem5 doesn’t seem up to the task for my use due to being slow and having short battery life, the PinePhone Pro has more powerful hardware and allegedly has better battery life [11] so it might work for my needs. The PinePhone Pro probably won’t meet the desktop computing needs of most people, but hardware keeps getting faster and cheaper so eventually most people could have their computing needs satisfied with a phone.

The current state of software for convergence and for Linux desktop security needs some improvement. I have some experience with Linux security so this is something I can help work on.

To work on improving this I asked Linux Australia for a grant for me and a friend to get PinePhone Pro devices and a selection of accessories to go with them. Having both a Librem5 and a PinePhone Pro means that I can test software in different configurations which will make developing software easier. Also having a friend who’s working on similar things will help a lot, especially as he has some low level hardware skills that I lack.

Linux Australia awarded the grant and now the PinePhones are in transit. Hopefully I will have a PinePhone in a couple of weeks to start work on this.

2 comments to Considering Convergence

  • Dear Russell, thank you for writing the article and working on this issue. Some questions and thoughts:

    1. What is the performance and specs of current flagship highend phones – for example from Google, Samsung and Apple?
    2. > The PinePhone Pro probably won’t meet the desktop computing needs of most people, but hardware keeps getting faster and cheaper so eventually most people could have their computing needs satisfied with a phone.

    What are desktop needs of most people? Nowadays most people just use the browser, and the phones have GPUs fast enough to render smoothly on (several(?)) 4K displays and also have special units for displaying videos? So the need for over 50 % of the people should be satisfied?

    Kind regards,


  • 1: I don’t know. I plan to try and find out.
    2: Correct, but the PinePhonePro seems faster and as you note hardware keeps getting faster.

    The desktop needs of most people are small. Back in 1997 when laptops were significantly slower than desktops some managers had laptops on their desks as status symbols, so presumably even in 1997 people didn’t need the full performance of a desktop system to do wordprocessing etc.

    FullHD monitors are still very popular for corporate use and all the high-end phones have displays with higher resolution than that. On the Dell Australia web site there are 54 monitors advertised, of them 20 are FullHD and one is 1280*1024. Dell Australia only offers 8 monitors in 4K resolution (some of which are affordable) and 2 in resolutions higher than that (which are ridiculously expensive). The internal displays on phones are approaching 4K, the highest currently available is the Galaxy S23 Ultra 5G with a ridiculous 3088*1440 resolution. Dell isn’t the only hardware vendor, but I think it’s range of products matches what corporations want and that clearly means a lot of FullHD displays (as an aside I have not yet managed to convince my employer that 4K is the correct choice for monitor purchases).

    For people like you and I there are some issues that need to be addressed regarding video support in phones, before I get the software working acceptably the 5K displays will probably become affordable (needs to drop from $AU2500 to about $AU800). 5K monitors and multiple monitors will take more time to get good support in phones, but it will happen eventually. The limits of human vision will be hit before the limits of how much IO can be done by a phone.

    For most people moving to laptops only and no desktops will happen in the near future. Currently laptops are price competitive with desktops at the low end of the market and most people will get the cheapest option. See my next blog post.