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Google Summer of Code 2025 Mentor Summit in Munich, Germany: travel notes
October 31, 2025 posted by Leonardo Taccari
I just came back home from Google Summer of Code 2025 Mentor Summit. We were 185 mentors from 133 organizations and it was amazing!
Google Summer of Code (GSoC) is a program organized by Google with the focus to bring new developers to open source projects.
The NetBSD Foundation has been participating in GSoC since 2005.
After nearly a decade being part of GSoC for The NetBSD Foundation, first as student and then as mentor and org admin, I finally attended my first GSoC Mentor Summit! That was a fantastic, very intense and fun experience! I met with a lot of new folks and learned about a lot of other cool open source projects.
Let's share my travel notes!
Wednesday 22, October 2025: arriving in Munich
Going to Munich is relatively doable by train from my hometown. I departed from Urbisaglia-Sforzacosta at 6:59 in the morning. I had around 25 minutes to wait for the change from Ancona to Bologna. I arrived in Bologna at around 11:30 where I met Andrea, my friend and favorite music pusher since childhood. We had lunch together, eating tasty miso veggie ramen, drank some hot sake and then we had coffee. He then accompanied me back to the station where I had the train to Munich Central Station at 13:50.
The scenery from the train was really nice. Near Trento and Bolzano/Bozen, full of vineyards and apple orchards with mountains in the background. It was cloudy for most of the travel but starting from Bressanone/Brixen I began to see «beautiful blue skies and golden sunshine». After Bressanone the scenery was more uncontaminated with light green grazing lands. Unfortunately when reaching Brennero/Brenner (last Italian city before Austria) it started to get dark and I had not enjoyed the rest of the scenery in Austria and Germany. I arrived in Munich at 20:50 and checked in at my hotel which was around 1km from the station.
For this journey I was not alone! Also Christoph Badura (<bad@>) was a delegate for Google Summer of Code and we had been in touch to get dinner and beers together. Christoph had some train delays but at 21:40 we were able to meet and went for a walk a bit to the south-east to find some places to eat and drink. I had done my homework for the beer places (obviously!) but the place in my TODO list to visit on Wednesday did not have a lot of food so we decided to first go to a restaurant and we found Ha Veggie - Vietnamese Cuisine. I had some Edamame and Bò xào sả ớt, a delicious dish with seitan, vegetables, lemongrass and chili pepper.
We then stopped at Frisches Bier, a bit too late, but the publican was kind enough and she permitted us a last round. I had a pint of a refreshing Hoppebräu Wuide Hehna Session IPA.
We then took a walk back to our hotels, talked a bit and went to sleep.
Thursday 23, October 2025: 1st day of Mentor Summit
Thursday was the first day of the Mentor Summit. The summit was in Munich Marriott Hotel, more in the north of the city, around 5km from the central station.
I checked out of my hotel and walked to the city center in Marienplatz and nearby. I also stopped in a couple of shops to grab some souvenirs for my family and friends and then took a long walk in the direction of Munich Marriott Hotel, to hopefully be there at 13:00 sharp for the start of check-in of GSoC Mentor Summit.
Rear of the Siegestor showing its inscription that can be translated to "Dedicated to victory, destroyed by war, urging peace"
I walked through Ludwigstraße and enjoyed the architecture around me, walking near LMU University and Siegestor. I then proceeded through Leopoldstraße and Ungererstraße and then arrived to the Munich Marriott Hotel.
Chris was already in the lobby and he had already checked in. We talked a bit and then I checked in as well. The room was huge and comfy! I quickly went back down to the lobby. We then checked in for Mentor Summit and I finally met Stephanie, Mary and Lucy, the GSoC Program Admins. I also took with me from home some classical and specialty Italian chocolate (Cioccolato di Modica) for the chocolate room (more about that later!) and left the bars in the chocolate room.
The time from 13:00-17:00 was reserved to actually permit mentors to arrive. At 13:00 there were still not a lot of mentors around so with Chris we decided to have lunch. We had lunch in a trattoria where we had an antipasto of grilled vegetables, penne all'arrabbiata with red wine from Montepulciano.
While eating Chris talked about the Tantris but we were already full. We had not tasted the haute cuisine but walked there to just look at the restaurant building. O:)
Tables full of chocolate and sweets from the chocolate room
When we came back to Munich Marriott Hotel, I went to the chocolate room to taste some chocolate/sweets. In GSoC Mentor Summit it is a tradition to bring great quality chocolate - or other sweets for places where chocolate is less usual - so folks can taste sweets from all over the world. That's a very nice initiative! I was curious more about non-chocolate sweets completely new to me so I had some Laddu and Kaju katli, both delicious!
I spent the rest of the afternoon down at the Champions Bar socializing with other mentors.
We had dinner at around 19:00 with good food accompanied by a couple of glasses of Primitivo.
At 20:15 we had the Opening Session. Stephanie, Mary and Robert warmly welcomed us. They shared the schedule and introduced to the unconference format of the sessions. We then had dessert and played the GSoC 2025 Mentor Summit Scavenger Hunt. The Scavenger Hunt is a game where you can meet and find 25 different folks with something that could be common (e.g. «prefers spaces (not tabs)») to something pretty rare (e.g. «has jumped out of a helicopter»). This game was nice because it was also a great conversation starter. I met a lot of mentors both of open source software that I regularly use but also learned about new interesting open source software and organizations while doing that!
We had time until Friday 12:30 and 10 lucky mentors who completed it (at the end around 60 of 185 were able to complete) got randomly selected and they got special prizes.
I stayed up until probably 1am or so, socializing a bit more in the lobby and then went back to my room to have some sleep, knowing that Friday was completely packed with Lightning talks and sessions!
Friday 24, October 2025: 2nd day of Mentor Summit
I had breakfast around 8:20 at the Green's Restaurant. I sat at a table together with other folks and after a minute I saw a known name in front of me: Lourival Pereira Vieira Neto <lneto@>! I was very happy to meet another NetBSD developer and that was a complete surprise. He was there as a mentor of the LabLua organization.
GSoC Program Admins welcomed us for the day and recapped the schedule for Friday and Saturday.
Lightning talks, round 1
The lightning talks consisted of mentors presenting their best GSoC 2025 projects. The format was fast and fun: a maximum of 3 minutes for the talk and a maximum of 4 slides! We had presentations from 18 different mentors and orgs and all of them were able to stay under 3 minutes!
That was a great occasion also to learn about open source projects, new orgs and the experiences shared were interesting too.
GSoC Feedback Session
After the 1st round of Lightning Talks I attended the GSoC Feedback Session. That was a Q&A session with program admins and org admins/mentors.
Hot topics this year were AI usage and spam applications that were not discussed as part of this session because there were two other separate sessions regarding that later.
If I only have one sentence to summarize this session... I should quote Robert sharing that Google Summer of Code is about the journey for the contributors and mentors to get involved in open source. The coding is only the means to an end.
"Hallway track", lunch and group photo
After the first session I decided to take a break and instead stay in the "hallway track" where I met new folks and socialized a bit. Another funny and at the same time a bit embarrassing for me thing of GSoC is that I often met someone and after a couple of minutes of talk I can associate the face with a name and I figured out that I'm an avid user / pkgsrc MAINTAINER of the software they contribute to! :)
At 12:30 we had lunch at Green's Restaurant and then at 13:40 we had a group photo and it was pretty tricky to put around 200 folks (program admins and mentors) on the stage of the Ballroom! :)
Let's talk about improving diversity + inclusion in FOSS!
In the afternoon I joined the session about improving diversity. In open source unfortunately there are a lot of underrepresented groups and we should fix that.
There were a lot of experiences shared from several orgs, food for thought for me! Only to name few topics: Outreachy, how to know and create safe spaces, importance of localization in software and documentation, be sure to make underrepresented folk as part of key people and also try to take the burden of other tasks off them.
GSoC and AI
Artificial Intelligence (AI), in particular Generative AI (GenAI) has been a hot topic since project proposals opened this year!
Some people consider it a speed-up for researching but at the same time it impedes learning.
In NetBSD - according to our Commit Guidelines - code generated by large language model (LLM) or similar technologies is considered tainted code because such models can be trained on copyrighted materials and such resulting code can then violate copyright.
More than 80% of GSoC contributors who filled an anonymous survey used AI, mainly for code generation, code completion, text generation, debugging and error detection.
Most mentors are usually not happy with the outcomes of AI with code often resulting in buggy/vulnerable and poor quality, violating copyright and some mentors also pointed out that as part of mentoring we should also make contributors aware of environmental/ecological impact of such use.
However, both contributors' and mentors' surveys on AI are relatively small dataset (around 90 mentors and 90 contributors).
Lightning talks, round 2
At 16:00 we had the 2nd and last round of Lightning talks. That was another great opportunity to learn more about more projects and organizations!
Asynchronous I/O by Ethan Miller
Christoph Badura (<bad@>) presenting his lightning talk
Christoph Badura (<bad@>) did a lightning talk too and he presented work done by Ethan Miller. Ethan also blogged about his work, please read Google Summer of Code 2025 Reports: Asynchronous I/O Framework if you missed it!
This code was also imported by Christos Zoulas (<christos@>), thanks Christos!, and is now part of -current and it will be in NetBSD 12.0.
GSoC spammy proposals
After the Lightning talks there was a break and then at 17:30 I joined the session about GSoC spammy proposals.
This year most organizations received many more proposals, mostly due contributors starting to massively use GenAI.
A lot of suggestions and tips were shared to make the mentor review job smooth and easy as possible.
The most important suggestion is that mentors must do a 1:1 conversation with potential contributors before accepting them. The weight of the project proposal is like 2/10 and the actual 8/10 weight is on conversations between mentors and contributor.
Dinner and social event
Around 19:00 we had dinner, desserts and socialized. Stephanie also did a final talk recapping GSoC 2025 and thanking all mentors for making that possible.
We then had drinks and it then started the karaoke session (and there were a lot of pro folks doing that, very nice!).
The karaoke session at Ballroom closed with the waiter singing Closing Time (not the one by Tom Waits that is mostly instrumental, but the one by Semisonics!, I did not know it but that's melancholic as well for me, just smells a little bit less of whisky and cigs compared to the Tom Waits one ;)).
We went downstairs to the Champions Bar, had two rounds of some good Higgins Ale Works IPA and socialized a bit more. Time passed pretty quickly and also the barman there at Champions Bar started singing Closing Time!
We went a bit outside and in the lobby talking with other mentors and then I went back to my room to get some sleep for the last day of the summit.
Saturday 25, October 2025: 3rd day of Mentor Summit
I had breakfast around 8:00, a bit earlier, given that on Saturday the first session started at 9:00.
Porting & Packaging
At 9:00 I joined a session about porting and packaging. We had both FreeBSD porters, pkgsrc maintainers and other package systems maintainers on one side. On the other side there were also a lot of upstreams.
We shared do-s and don't-s on packaging.
How to get students to engage with the community
Christoph Badura (<bad@>) proposed a session to share experiences on how to get contributors to engage with the community and a lot of mentors provided a lot of great suggestions.
One thing that most mentors agreed on and worked well was to invite contributors regular (or less regular, to avoid putting too much pressure on contributors) blog posts / status updates.
Some organizations also did that as part of their weekly / bi-weekly updates that are often video meetings. In that case they reserved a slot for the contributor so that they can share their status updates.
These are great opportunities for the contributor to get in touch with the community.
Open source tools for supply chain security
I then joined a session about open source tools for supply chain security.
We discussed about Software Bill of Materials (SBOM) and its importance in the context of regulations like EU Cyber Resilience Act (CRA).
We also discussed Common Platform Enumeration (CPE) and Package URL (PURL) schemas
We talked about vulnerability management and I shared a bit my experience in pkgsrc-security@ and how often the metadata in CVEs (like vendor, product and versions affected) is not that good. Most package systems have their own workflows and usually add extra metadata only for their vulnerability DB.
I also learned about Vulnerability Exploitability eXchange (VEX) that some package systems use.
There were also mentors from AboutCode and SW360, projects that looks very interesting and I should learn more about them!
Vintage computing
Before lunch I joined the Vintage computing session.
Everyone presented themselves and talked about the most vintage computer they had, how running old machines is both fun and productive and we also talked about old Unix-es and The Unix Heritage Society.
Lunch
I had lunch at Green's Restaurant with other mentors and then socialized a bit outside Ballroom.
Waitlisted Lightning talk and funny stories
At 14:00 we had the last sessions. I went to the waitlisted Lightning talk, that can be considered the Lightning talk, round 3! :)
Mentors from different organizations shared interesting projects.
After the lightning talks several of us shared funny stories/hacks. Like learning languages in interesting ways, taking photographs of garbage to train and realize a robot that cleans it, a sort of Tinder for food... And much more! :)
Closing session
At 15:30 we had the closing session.
Some of us stayed for another 1 or 2 hours and talked, socialized a bit more and said see you soon to each other.
Going near Munich East Station and dinner with Chris
Around 17:00 I left the Munich Marriott hotel to check in to my hotel for Saturday night near Munich East Station. It was raining for most of the morning and afternoon but luckily around 17:00 it stopped and the sky seemed fine. I decided to take a walk - a bit more than 6km - to reach the hotel. Also that time I'm happy that I took a long walk because I was able to stay for most of my walk in the Englischer Garten.
Glass of Camba Island (NEIPA) beer and list of draft beers
I checked in at my hotel and then went to Tap-House where with Christoph we planned to have dinner and a couple of beers. Tap-House had a really huge choice of craft beers with 40 drafts! We had a pinsa marinara, a flatbread similar to pizza and I had a couple of small IPAs from Camba Bavaria and Yankee & Kraut Pure HBC 630, a DNEIPA.
We decided to take a walk and went to BrewsLi for some last good night beers. BrewsLi was a very nice brew pub. We sat at a table and near us there were several board games. Chris took one of this board game Mensch ärgere Dich nicht and explained to me the rules. A lot of aleatory is involved but there is also some strategy and it was funny to play and we probably played for 40 minutes or so because most of our game pieces returned to the "out" section. I took a walk with Chris back to the nearest metro station and I came back to my hotel around 2:00.
Mensch ärgere Dich nicht board game
Sunday 26, October 2025: stop in Bolzano/Bozen
On Sunday I took a train from Munich East Station to Bolzano/Bozen because it was unfeasible to go back home by train to Marche region without a stop somewhere in Italy.
View of Bolzano from St. Oswald Promenade
I went for a walk Passeggiata di Sant'Osvaldo (St. Oswald Promenade) uphill to be able to enjoy a view of the city from the top until sunset.
I had a simple but very tasty onion soup and a Gose (really good, one of the best Gose I've drunk!) and Session IPA at Batzen Häusl.
I was not able to visit anything else in the night because I was pretty tired so I went to sleep earlier.
Monday 27, October 2025: back home
In the morning I took a walk to Walther Square and nearby. I got some souvenirs for the family and then I took the trains back home and spent most of my day on the trains.
Conclusion
Google Summer of Code 2025 Mentor Summit was an amazing experience!
I had the chance to participate in very interesting talks, sessions and discussions. I met a lot of mentors from all over the world and learned about new open source projects and organizations. All the folks were also extremely positive, easy to talk to and I had a lot of fun.
Thanks to program admins and all the mentors who made this possible! Thanks a lot also to Google for organizing it and thanks to The NetBSD Foundation that permitted me to go!
NetBSD hand-written logo on the GSoC guest book
If you are new to open source, consider applying for it! If you are a seasoned open source contributor, consider participating as a mentor! You can learn more about GSoC at Google Summer of Code (GSoC) website.
