Shiraz Memon successfully defended his PhD thesis in Computer Science on Federated Access to Collaborative Compute and Data Infrastructures. The thesis covers how researchers can perform eScience by discovering services (such as accessing data and processing data) on remote research and e-infrastructures and authenticate (such as logging in order to use the service) and how authorization can be done (i.e. deciding which services are allowed to be used).

The thesis was streamed, Wed, 30. June 2021 starting from 09:30 (UTC), and the recording is available via: https://livestream.com/hi/doktorsvornshmedshirazmemon

This PhD is an example of the collaboration between the Faculty of Industrial Engineering, Mechanical Engineering and Computer Science and Jülich Supercomputing Centre (JSC).

Members of the PhD commitee were Morris Riedel, Helmut Neukirchen, and Matthias Book, opponents were David Wallom and Shukor Abd Razak. The head of faculty, Rúnar Unnþórsson, was steering the defense.

While I intended to use a Raspberry Pi 4 as a small server, I also ordered from China a small system (BEBEPC, comparable to the Qotom mini PCs. While Qotom mini PCs are slightly better documented, they typically have less powerful CPUs: even though they have Core i3 CPUs, these are so old that a more recent Celeron CPU is faster) based on a Intel J4105 CPU (= TDP of 10 W, 4 cores, 1.5 GHz base frequency, 2.5 GHz burst frequency) which has over the Raspi the advantage of native SATA ports (one standard SATA connector with 5 V power supply and one mSATA connector carrying 3.3 V power supply -- I ordered an mSATA to SATA adapter and a 5 V SATA power splitter cable to be able to have a RAID system of two SATA SSDs -- mSATA SSDs are only available in smaller sizes. But note that the SATA ports are only 3 Gbit/s, i.e. 300 MB/s, which means that a 500 MB/s SSD is already overkill). However, the biggest advantage is that it is (obviously) able to run Intel-only code, e.g. in particular Virtual Machine images or containers only available for Intel, e.g., using Proxmox VE.

Both systems come with 8 GB LPDDR4 RAM, but for the J4905, even 16 GB are possible (see below).

Both systems can be passively cooled: for the Raspy, I used a cooling case from https://www.coolingcases.com/ -- it cools well, but the metal affects the range of the onboard Wifi (not that relevant for a server). The J4105 came as well with a case that allows passive cooling -- while it is still tiny for a PC, it has approx. 4 times the volume of the Raspi.

As you can see in the above photos, squeezing to SATA SSDs (for RAID) was a challenge and I had to bend the connector cables very tightly (which might not be healthy for the connectors, cables, PCBs). Therefore, I had considered removing the 2.5" case from the SATA SSDs and using only the bare PCBs. But as you can see in the photos below, there were pads glued to the SSD controller chip and I am not sure whether these are thermal pads and the metal case is needed as heat sink. Hence, I decided to keep using the case. (On the other hand, the second pad is only marginally covering the two NAND chips and the NAND chips on the second side of the PCBs are not padded at all -- so maybe, the pads are just mechanical to prevent rattling.)

SSD case open (HDD for comparison)

SSD PCB with pads (are these thermal pads?)

The J4105 system has for sure more compute power than the Raspi's ARM CPU, so the remaining question is the power consumption. Hence, I did some tests and measurements using a cheap power meter that claims to have a 2% precision. Both systems were connected via FullHD HDMI to a monitor.

Intel J4105 measurements

As at the beginning, I did not had installed Linux yet, it was running Windows 10 and idle refers to having only the built-in task manager running in foreground (to display clock frequency) and all the background services that Windows 10 has by default. CPU load was generated using a batch file containing an endless loop.

The J4105 clocks down to 0.78 GHz when idle and the power consumption of the whole system (with one mSATA and one SATA SSD) is then 3.8 W.

With 1 core being busy, it still clocks up to 2.4 GHz and consumes 7.2 W.

With 2 cores being busy, it still clocks up to 2.4 GHz and consumes 10.3 W.

With 3 cores being busy, it clocks up to 2.35 GHz and consumes between 11.8 W and 12.1 W.

With 4 cores being busy, it clocks up to 2.19 GHz and consumes between 11.4 W and 12.0 W. (So it seems the reduced clock saves power).

I did run it with 4 cores being busy for an hour, and the measurements did not change, e.g. no thermal throttling seems to have occurred (nor did the case get hot, so a really good passive cooling -- or the contact between CPU and case is bad, but then thermal throttling could have been expected).

Raspberry Pi 4 measurements

I had OSMC with KODI running, but nothing else, i.e. the KODI UI being idle, but all the background services running. The latest firmware as of 4. June 2021 was used, storage was SDHC card only. CPU load was generated using the stress command.

The Raspberry Pi 4 consumed idle 3.8 W to 4.0 W.

With 1 core being busy, it consumes 4.5 W.

With 2 cores being busy, it consumes 5.0 W.

With 3 cores being busy, it consumes between 5.4 W and 5.5 W.

With 4 cores being busy, it consumes 6.0 W.

Temperature with the cooling case from https://www.coolingcases.com/ was approx. 52° C (so it prevented thermal throttling that would start at 80° C). Surprisingly, even in idle mode, the temperature was 40-42° (the tiny case does feel much warmer than the bigger case of the Intel system -- so, it seems: size matters).

Conclusions

In summary, the idle power consumption of both systems is comparable and while the busy consumption is lower with Raspberry Pi 4, it is of course less powerful than the J4105 system. For the J4105, I never observed the full 2.5 GHz burst clock rate (but 2.4 GHz). Even though the CPU TDP is 10 W, the whole system consumed up to 12.1 W (e.g. the RAM, the two SSDs, WiFi, HDMI output, external power supply, etc. probably also to add their share -- during boot, I even saw 14.8 W).

Note that others suggest 2.7 W idle for the Raspi 4 (but seems to require switching off a lot of I/O, e.g., HDMI etc. -- which I did not do, nor did I minimise background processes) or even as low as 2.1 W. On the other hand, many other report that they neither (with either a fan or a heatsink) get the system cooler than 42° in idle, so getting the Raspy warmer than the touch of your hand seems to be normal, but the J4105 system with the bigger case was considerably cooler.

It seems that the J4105 is a good 24/7 home server system, i.e. more powerful than the Raspi when needed, but still not consuming more power when idle. (A German c't article confirms this for a thin client that is also J4105-based.)

The ultimate passively cooled server with ECC ram would be ASRock Industrial iBOX-V2000M or iBOX-V2000V -- but these are not available for private users. But any ASRock motherboard in general, together with AMD Pro CPUs should support ECC.

Some documentation on the BEBEPC system

RAM: 16 GB DIMMs supported

An even more powerful system based on J4125 (= J4105 with higher clock) suggests that with Dual-Rank-Modules even 16 GB per RAM module are possible, i.e. with two banks, even 32 GB of RAM. Power consumption of that J412-based system has also been measured which is higher (best explained by the fact that it is faster, i.e. cannot clock down as much: 2000-2700 MHz vs. 1500-2500 MHz).
I therefore ordered a 16 GB DIMM: I can confirm that this works. However, my system has just 1 RAM socket, so 16 GB is the maximum.

Auto power on

It seems that to make the system automatically power-on after a power outage, a jumper needs to be set at PWRON1 at the pins marked PWR_SW1.

Independent from that, the system does not start after having been powered off -- not even after the power button has been pressed: in this case, the RTC/CMOS battery needs to be removed and inserted again.

BIOS settings

F11 or DEL to enter the AMI BIOS.

F2 to select boot drive.

MAC address can be found via Advanced.

Change OS to Linux via Chipset-South Bridge.

Change SATA Device Type to SSD via Chipset-South Cluster Configuration (not sure whether Mechanical Presence Switch setting matters and needs to be disabled).
Not sure about DITO (the time a given port must be idle before HW may enter DevSleep autonomously): might help if SSD gets hot/consumes to much energy.

Chipset-Miscellaneous Configuration: Power Button Debounce Mode disable to make the power button to come back from standby mode.

Security-Secure Boot: Disable if booting Linux causes problems.

Security-Quiet Boot: Disable to see some BIOS messages at boot.

Boot: Change order of boot devices.

US keyboard

On German/Icelandic keyboards, the pipe symbol is left of the enter key.

Update 2023: Intel N100, N200 and N300/N305 Alder Lake N CPUs

The Intel N100, N200 and N300/N305 CPUs are some sort of successor of the J4105 CPU. N100 and N200 have both 4 cores and N200 can clock higher and has a better GPU than N100. The numbering is a mess (e.g. N95 is faster than N100), as a rule of thumb: those CPUs ending with the digit 5 are allowed to get hotter (i.e. higher TDP), i.e. they can probably sustain longer using all cores at highest speed. But I do not know what the reason for the different TPD is (are the different TDPs the same die, but just the production results get selected?). N300/N305 has 8 cores and also marketed as "Core i3". All support 2.5 Gb Ethernet. While they support only one DIMM (i.e. single channel being slower than two memory channels), they support DDR5 RAM which is anyway 50% faster.

If the BIOS supports it, these system even allow ECC, see my post on the iKOOLCORE R2 for more details on the ECC. Even if the BIOS does not support enabling IBECC, there are claims that using the AMISCE tool from AMI, you can set this from command line (and then reboot -- just take care that you can clear the CMOS/NVRAM or have some rescue mode), e.g. on Linux, this is the SCELNX_64 / scelnx tool, but maybe the uefisettings tool works as well?

That Chinese Intel i3-N305 fanless mini PCs look also good, but you never know what backdoors are int the BIOS. The Protectli systems have coreboot, but are more expensive and have outdated hardware, i.e. none of these new processors. Starlabs Byte has an N200 with coreboot, but DDR4 RAM only. The official maximum RAM is 16 GB according to Intel, but there are systems offered with 32 GB:

• TerraMaster F4-424 Pro NAS with N300 and 32 GB RAM. (While Terramaster is Chinese, it might be interesting to see when the non-Chinese QNAP and Synology offer Alder Lake N-based systems, but in contrast to TerraMaster, installing your own Linux, e.g. TrueNas Scale, is not well supported.)
• CWWK Magic Computer with various CPUs and RAM configuration and it has even a PCIe socket
• iKoolCore R2 it has a fan but is super tiny. For details, including getting ECC to run on Linux, see my blog post on the iKOOLCORE R2.
• ODROID H4 from Hardkernel which is South-Korean, so no China BIOS -- hence the ODROID H4 sounds a very good buy and also the support provided by Hardkernel seems to be good. But it does not come with a decent case. If you sacrifice the NVM SSD, you can use the NVM port (which is in fact just PCIe) to add 4 further 2.5 Gb Ethernet ports, making it a great router, however you then either need to use the slow eMMC or the SATA ports for storage.
• You can also find many more devices at AliExpress...

Note that most of the above come with Intel Ethernet Intel i226 chips that have a good driver support in Linux and BSD, however there are claims that these chips crash after a couple of hours and the only way to prevent this is to switch of PCIe power saving (ASPM) -- on the other hand, you find people reporting their n100 systems with i226 running rock-solid.

In general, these new CPUs are slightly faster than, e.g., a 8 core C3758 Xeon-like Atom CPU that is three years older, but supports more RAM and even ECC. But these new CPUs are more I/O limited (in terms of PCI lanes) in comparison to that 8 core C3758 Xeon-like Atom CPU that has 25 W but can still be passively cooled.

A test of an Intel N200-based fanless mini from Asus with DDR4 RAM mentions that N200 with DDR5 RAM is faster. Idle power consumption is claimed to be 5-6 W and 22 W under full load.

Others show for a N305 system idling 15-16 W which is significantly more. (But the N305 has 15 W TDP vs. 7 W for the N300 -- otherwise, both CPUs are exactly the same; I guess, the N300 will simple start to throttle when stressing all cores. But the N305 can also be restricted via BIOS to a lower TDP.) There, you find also a performance comparison with a Raspberry Pi 4 and Pi 5: N100 is twice as fast as a Pi 5 and four times faster than a Pi 4, and N305 is almost twice as fast as an N100.

Studying Software Engineering is important because Software is the future and future is starting right now. And someone needs to create all this software that is shaping our future.

Software Engineering is more than just programming, it rather looks at big picture , namely the whole life of the software: from the start where you need to talk to customers to find out what software they actually need over to the actual programming, user interface and user experience, quality assurance and this is all guided by project management where you need to make people work together.

Software Engineering covers so many different aspects that students need to come from all kinds of different backgrounds:
female and male, those who are good at math, those who are good at communicating with other people, those who are picky about details, those who are creative. Essentially everyone!

When you start studying Software Engineering, you do not need to be able to program: you will learn that in our courses. But you need to be able to talk to other people and at the same time do not fear thinking like an engineer, such as doing math and applying systematic processes!

The nice thing about developing software is that only your imagination is the limit: you can create everything just by turning your mind into code and then it runs and you can see it immediately working. This is so rewarding!

Studying Software Engineering at the University of Iceland is very practical: you do not only learn the theory, but also apply it in the courses. For example, in our Bachelors program, there is a Software Engineering project that spans a whole full year.

Those who graduate from here, will find easily a job at a good salary and can work in fact in all kinds of different fields: be it banking, insurance, health, industry, administration, tourism, gaming, even arts:
simply everywhere, Software is nowadays needed!

Further information

If you want more information on our Software Engineering programmes:

Bachelor (B.Sc.)

Software Engineering (Hugbúnaðarverkfræði)

Master (M.Sc.)

Software Engineering (Hugbúnaðarverkfræði)

Ph.D.

And of course, you can also do a PhD in any of these programmes. Before you apply, contact a professor: either by a personal visit or -- if you are located abroad -- by writing an old school paper letter (professors get hundreds of email with PhD applications where it is obvious that the same email was written to many professors and thus, these email are considered as spam -- but a paper mail makes an impress)!

If you rather want to study Computer Science or Computational Engineering

While the above text was intended to convince you studying Software Engineering, you might still be interested in our other programmes:

Bachelor (B.Sc.)

Computer Science (Tölvunarfræði) -- we added recently the specialisation in Data Science

Master (M.Sc.)

Computer Science (Tölvunarfræði)

Computational Engineering (Reikniverkfræði)

Salary

For a salary (typically distinguished: base salary and overall salary with the typical amount of paid overtime – overtime is not always paid, though) outlook, you can find surveys on Icelandic salaries at unions (stéttarfélag), e.g.:

• VR (starfsheiti “Tölvunuarfræðingur”)

and at professional associations, e.g.:

• Software Engineers: Verkfræðingafélag Íslands (VFÍ)
• Computer Scientists: Félag Tölvunarfræðinga (FT) (only for members)
• Félag Hugbúnaðarprófara á Íslandi (Hugpró) (only for members)

In addition there is also on interesting blog post on the different companies and their salaries (Netherlands -- Iceland might be different).

But be aware that salary alone is not everything, but work-life balance counts or that big and old companies are typically less chaotic (i.e. have well defined procedures) which may give you as a beginner more guidance, but you might at the same time fell more restricted.

The Horizon 2020 Future and Emerging Technologies programme: Dynamical Exascale Entry Platform - Extreme Scale Technologies (DEEP-EST) project has finished its work and was praised for its results in the final review of the project's outcome.

We still have to harvest our results by writing publications on the results, but you can find a video already here:

All our travel emissions have been offset. As it is not clear whether funding regulations allow to offset emissions due to supercomputer energy consumption, these were not compensated. However, one of the research topics of the DEEP-EST project was energy efficiency and we achieved a lot by using specialised (=more efficient) accelerator hardware.

The European Centre of Excellence RAISE (Research on AI- and Simulation-Based Engineering at Exascale) is holding an online seminar on using the Interaction Room Software Engineering approach for HPC Systems Engineering.

This approach has been described in this publication:
Matthias Book, Morris Riedel, Helmut Neukirchen, Markus Götz.
Facilitating Collaboration in High Performance Computing Projects with an Interaction Room.
The 4th ACM SIGPLAN International Workshop on Software Engineering for Parallel Systems (SEPS 2017). Co-located with SPLASH 2017 as an ACM SIGPLAN-approved workshop.
October 23, 2017, Vancouver, Canada. DOI: 10.1145/3141865.3142467, ACM Digital Library 2017.
Download

The recording of the online seminar can now be found on the CoE RAISE YouTube channel:

HÍ eða HR / University of Iceland vs. Reykjavik University

Often, the question arises whether University of Iceland (Háskóli Ísland (HÍ)) or Reykjavik University (Háskólinn í Reykjavík (HR)) is better for studying Computer Science (tölvunarfræði) or Software Engineering (hugbúnaðarverkfræði).

In my experience both universities do not differ that much -- on the surface things might look different, but when you look closer, they are not that different. As an example: HR advertises 3 week intense courses to apply the theoretical foundations learned in earlier courses, whereas at HÍ, the application of the learned theory is built into the courses themselves: either as a project at the end of each course or a project running even throughout the whole course semester.

However, there is one difference (in addition to paying high tuition fees at HR): the diversity choice of courses from other disciplines. At HÍ, you can take non-CS or non-SE courses as part of your studies -- and these can not only be other STEM (Science, Technology, Engineering, and Mathematics) courses, but also, e.g., foreign languages. As HR is quite limited in the number of course due to their limited number of study programmes, HÍ has a big advantage there.

Tölvunarfræði eða Hugbúnaðarverkfræði / Computer Science (CS) vs. Software Engineering (SE)

Another question is about the difference between Computer Science (Tölvunarfræði) and Software Engineering (Hugbúnaðarverkfræði): while both are in essence about programming, Software Engineering goes beyond as it has the "big picture" in mind -- not only, e.g., the big picture of a software architecture, but also related to management, e.g. project management and quality management. For example, SE students take courses from Industrial Engineering on project management and quality management (in addition to software quality management offered by me). When it comes to stakeholder relations (one of the biggest problems in software project are unclear requirements where the developed software does not meet the needs of users) and to user experience, SE requires many soft skills -- including psychology (e.g. work psychology and human-computer interaction and usability).

One might be tempted to say that CS is maybe for the nerds and SE for those who can talk to people and lead projects. But in fact, SE is not solely about soft skills, but you need both: soft and hard skills. Being an Engineer is an officially licensed professional title and as such, the regulations that apply to the contents of any Engineering programme in Iceland apply as well to Software Engineering, e.g. taking a certain amount of Math and Science courses which is the exact opposite of soft skills. So, to be a good Software Engineer you need to have both talents: people and tech.

Note that even if you enroll in our Computer Science programme, it allows so much freedom in selection of courses that you could take the same courses that a Software Engineering student has to take. (However, in this case, you will not be entitled to apply for a license as professional Engineer as you did not study any Engineering, but a Science, namely Computer Science.)

Further information

If you want more information on our programmes:

Bachelor (B.Sc.)

Computer Science (Tölvunarfræði) -- we added recently the specialisation in Data Science

Software Engineering (Hugbúnaðarverkfræði)

Master (M.Sc.)

Computer Science (Tölvunarfræði)

Software Engineering (Hugbúnaðarverkfræði)

Computational Engineering (Reikniverkfræði)

Ph.D.

And of course, you can also do a PhD in any of these programmes. Before you apply, contact a professor: either by a personal visit or -- if you are located abroad -- by writing an old school paper letter (professors get hundreds of email with PhD applications where it is obvious that the same email was written to many professors and thus, these email are considered as spam -- but a paper mail makes an impress)!

The University of Iceland's Computer Science department is researching machine learning using the next generation's supercomputer DEEP-EST -- by the way: we are also offering a Data Science specialisation in our Computer Science programme, where, e.g., machine learning including deep neural networks is covered. To showcase what is possible if you have a supercomputer to train neural networks, we offer a web page that allows you to use the camera of your smartphone (or laptop) to detect objects in real-time.

Just open the following web page and allow your browser to use the camera: https://nvndr.csb.app/
(Allow up to approx. 1 minute for loading the trained neural network and for initialisation. Web page works best in landscape orientation.)

While neural networks are still best trained on a supercomputer, such as DEEP-EST with its Data Analysis Module, the trained neural network even runs in the browser of a smartphone (purely running locally as Javascript in your browser without any connection to a supercomputer, i.e. completely offline after having downloaded the Javascript code and the trained neural network).

The used approach is Single Shot Detector (SSD) (the percentage shows how sure the neural network is about the classification) using the MobileNet neural network architecture. The dataset used for training is COCO (Common Objects in Context), i.e. only objects of the labeled object classes contained in COCO will get detected. The Javascript code that is running in your browser uses Tensorflow Lite and its Object Detection API.

Example object detection via a neural network

If you want learn more about the DEEP-EST project where the next generation supercomputer is developed, have a look at the poster below (click on the picture below for PDF version):

University of Iceland is part of the European Centre of Excellence RAISE (Research on AI- and Simulation-Based Engineering at Exascale) that has started in 1/2021 and will end 6/2024. It is funded by the European Commission's Horizon 2020 programme with an overall budget of € 4 969 347. The University of Iceland's team is lead by Morris Riedel together with Matthias Book and Helmut Neukirchen (all professors at the Faculty of Industrial Engineering, Mechanical Engineering and Computer Science) and several PhD students are funded by this project.

Compute- and data-driven research encompasses a broad spectrum of disciplines and is the key to Europe’s global success in various scientific and economic fields. The massive amount of data produced by such technologies demands novel methods to post-process, analyze, and to reveal valuable mechanisms. The development of artificial intelligence (AI) methods is rapidly proceeding and they are progressively applied to many stages of workflows to solve complex problems. Analyzing and processing big data require high computational power and scalable AI solutions. Therefore, it becomes mandatory to develop entirely new workflows from current applications that efficiently run on future high-performance computing architectures at Exascale. The RAISE Center of Excellence for Research on AI- and Simulation-Based Engineering at Exascale will be the excellent enabler for the advancement of such technologies in Europe on industrial and academic levels, and a driver for novel intertwined AI and HPC methods. These technologies will be advanced along representative use-cases, covering a wide spectrum of academic and industrial applications, e.g., coming from wind energy harvesting, wetting hydrodynamics, manufacturing, physics, turbomachinery, and aerospace. It aims at closing the gap in full loops using forward simulation models and AI-based inverse inference models, in conjunction with statistical methods to learn from current and historical data. In this context, novel hardware technologies, i.e., Modular Supercomputing Architectures, Quantum Annealing, and prototypes from the DEEP project series will be used for exploring unseen performance in data processing. Best practices, support, and education for industry, SMEs, academia, and HPC centers on Tier-2 level and below will be developed and provided in RAISE's European network attracting new user communities. This goes along with the development of a business providing new services to various user communities.

The Computer Science department of the University of Iceland is part of Erasmus+ and as such it is possible to have exchange of students (and also teachers) with other universities abroad (incoming and outgoing).

For an exchange, a bilateral contract between the two universities needs to be set up. Currently, we have the following contracts, but new contracts can be set up on demand:

Johannes Kepler University Linz
University of Antwerp
ETH Zürich
Universität Duisburg Essen
Georg August Universität Göttingen
Technical University of Munich
Universidad Complutense de Madrid
Université du Luxembourg
University of Groningen
Lodz University of Technology
Glasgow Caledonian University

In particular for German speaking universities, I can serve as a contact point.

Wacom tablets, including digitisers in screens, should be supported out-of-the-box with Linux.

I have a dual screen setup and a Wacom tablet. As one screen is 4K UHD and the other FHD, this is too much screen estate for my shaky hand on the tiny Wacom tablet that I have (the tablet has 2540 lpi resolution, so this is not a restriction of the tablet, but the blame goes to me). Therefore, I want to restrict the tablet use to the FHD screen only in order to get a more calm pen usage.

On my Debian KDE system, this can be done by two means:

• Install the KDE Wacom configuration tool via Debian package kde-config-tablet. In that tool, either set the mapping of the Wacom tablet to a specific screen (do not forget: you need to click "OK" also on the initial overview screen, i.e. end the whole setting process). Or use the pre-defined keyboard shortcuts to set a tablet-screen mapping.
• Use the command line tool xsetwacom: get the screen name via xrandr (e.g. eDP for my laptop screen) and, get the name of the Wacom tablet via xsetwacom --list. Note that multiple entries are listed there for the same tablet: take care to use the one that ends with stylus. In my case, I use
  xsetwacom set "Wacom Intuos S Pen stylus" MapToOutput eDP

In online teaching, I enjoy using to draw on slides. E.g. for drawing on PDFs, I use either KDEs okular PDF viewer (in presentation mode, move to the upper screen edge to get a menu with pen colors) or xournal or rather it's fork xournal++/xournalpp. While I run PowerPoint on Linux with Wine, exactly the presentation mode drawing function does not work (I see the dot representing where the pen would draw, but drawing does not leave a trace).

For using the pen in Gimp, it is important to understand that the Gimp drawing tool that shall to be mapped to the pen needs to be selected from the Toolbox window with the pen itself! (The pen and the mouse have different tools associated and Gimp distinguishes this based on what input device is used to selected the tool. Trying to select the tool with the mouse and then using the pen will only lead to making the pen crop (which is probably the default behaviour): this mode is also displayed at the bottom: "click-drag to draw a crop rectangle".)