Linux Archives - JasonGi

Fixing the Siemens SINUMERIK 828D when USB drives won’t mount

I came across an interesting problem the other day. All of a sudden, after saving a particular file to USB on the SINUMERIK 828D (a popular CNC machine controller) all USB drives stopped showing up on the HMI.

After looking through the file browser, you could see that /user/sinumerik/mnt/USB had the file in it – even when a USB was not plugged in. This is a common problem in the linux world. What probably happened is that for some reason, the HMI, saved the file to /user/sinumerik/mnt/USB, and then when plugging in the USB drive it would not mount as the directory already existed with files in it.

The next problem was – how do we fix it. We couldn’t delete the folder via the HMI, because there was inadequate permissions (even as the manufacturer user) so the end solution was to remove the system CF card from the unit, mount it on a linux computer (as it’s formatted ex4) with a USB CF card reader and then remove the file. Obviously this is risky, and you should always backup before attempting this. Another solution would be to SSH into the machine as root, but this requires it to be networked, and also the ability to get root access which I couldn’t figure out.

After mounting on a separate computer, we could see that the USB folder existed and had different permissions to the other drive mounts. After deleting the file and putting the CF card back in the 828D, USB drives were able to be mounted again.

Screenshot of 828D filesystem — You can see that the USB folder, unlike the other mounts, is not a link and does not allow non-root user’s write access

Linux.conf.au: Day 5 – The end

Today was the last day of linux.conf.au :(. Arguably some of my favorite talks were today.

This is a last continuation of this post here about my first Linux.conf.au, here.

The Keynote today was Deploying software updates to ArduSat in orbit by Jonathan Oxer [ Video ]. Basically this was a project which got it’s funding from kickstarter which allows low-cost experiments to occur on arduinos on cube satellites in Lower Earth Orbit. This really was a the future is now type talk. Never before would you have thought regular people would have a chance to do anything with space other than look at it.

Raspberry Pi Hacks: Building Great Pi Projects by Ruth Suehle and Tom Callaway [ Video ] was a pretty light talk about some different projects the speakers and others had achieved with the raspberry pi. It’s actually convinced me to give the pi another shot. I bought one when they first came out and used one for a bit as a torrent server however I found it kinda sucked with stability but I think part of that now has to do with my power adapter (apparently they have to be 5v 1A regulated) and the fact it was the original model (apparently things have been fixed in the newer ones). They also had written a book on the pi for sale here (the discount code AUTHD gives you 40% off!)

The Rust language: memory, ownership and lifetimes by Nicholas Matsakis [ Video ] was an introduction to the new Rust language being developed by Mozilla. Now I’m not an expert on rust, but from the talk my impression is that it is C++ with some extra checks to avoid memory management issues. Basically you have an owner (like a variable/pointer) of a piece of memory that the owner can lend memory to others or transfer ownership. This prevents aliasing and means there doesn’t need to be garbage collection which worries about reference counting and other things. Obviously there are some other additions, but this is the one that was mainly emphasised. Rust sounds like an interesting language, I hate memory issues as much as the next guy. However, one issue I had with this talk was that programming languages were evaluated on this zero sum balancing act between safety and control. C++ gives you lots of control but sucks at safety. Haskell is very safe, you have basically no side effects but you don’t have much control or freedom which is why it isn’t used much. Python is pitched as being somewhere in the middle. Rust however is pitched at being simultaneously giving lots of control and lots of safety, which I feel like was extending the truth a bit. Rust gives safety through the ownership system which forbids dangerous things like aliasing and shared memory. Rust offers C++ like freedom by having unsafe blocks, which do allow these things. Clearly an unsafe block is not safe. So can a language offer high control and high safety at the same time? I’m unconvinced, but I haven’t used rust, so maybe somebody could comment on how it makes their programs more safe. It seems to me like Rust mostly just enforces a commenting policy of marking areas of code where memory management is messy. I do believe Rust has the potential, because of these rules, to improve code readability and debugging, but only compared to poorly documented code.

Pettycoin: Losing Tiny Amounts of Bitcoin At Scale! by Rusty Russell [ Video ] – I was looking forward to this talk. I’m a fan of the Bitcoin protocol so generally new ideas excite me, plus Rusty Russell is super nice to newcomers which is always great! Rusty also admitted the idea and implementation is in it’s infancy. Firstly, let me say I like that he is thinking out of the box and I am so glad there are people out there making things that aren’t more alt-coins. Stop making alt-coins people! Rusty talks about some good ideas. Sharding the network is pretty smart, so is sending out double spend alerts and shirking transaction size. However it is fundamentally flawed. The reason is Gateways. Bitcoin is supposed to be decentralized and gateways are centralised. It seems like the whole protocol relies on gateways and because of this I don’t see any advantage this would have over sending your bitcoins to a dedicated, centralised micro-payment service (like paypal lite or something). I would even argue a dedicated micro-payment service would be more secure as there is no risk of double spends, only traditional hacking.

Finally there were lighting talks at the end. Mostly used as an opportunity for people to spruke their open source project or group, these are usually hit and miss. I’m excited I discovered DLect after mostly giving up on my blackboard scraper project, it turns out somebody from University of Queensland has had the same idea but gotten a lot further. Hopefully I can get it working with Curtin. There were also a couple of talks on Bitcoin. Lightning talks are free as in free speech, so they’re sometimes not the greatest. Here is my quick guide if you’re interested in spreading the word of bitcoin.

Don’t talk about it like it’s an investment or stock
Don’t talk about it like it’s going to make money (saving money (from fees) is OK)
Don’t be misleading by refering to thousands of % growth
Don’t talk about how it’s a “store of value”

Do talk about the lack of fees for transferring
Do talk about the decentralised nature of the protocol
Do talk about the safeguards against hacking (eg Proof of Work)

There tend to be two views on bitcoin, one is that it is a ponzi scheme and one that it is the future of money transfer. I think it’s both. There is no doubt that a lot of ‘early adopters’ will become very rich (or have done already) if bitcoin becomes mainstream, and many of them have become mouthpieces for bitcoin, but I think this does not detract from the theoretical qualities of bitcoin and that the protocol will still exist even when all the scheming has died down and the ponzi schemers have lost all their money.

So after that slightly divergent rant, LCA2014 is now at a close. LCA2015 was announced to be held in Auckland so maybe I’ll see everybody there next year! I’ve had a great time and I recommend any other student interested in Linux to take advantage of the cheap student entry.

Linux.conf.au: Day 4

It’s had now been 4 days since the conference began (I’m writing this in the past perspective because I’ve been lazy.). It’s only the second day of the “real” conference, where all the long, meat and bones talks were held.

This is a continuation of this post here about my first linux.conf.au, here.

First up we had Matthew Garrett deliver a great keynote speech, which was expected. I’d watched his talk the day before and I definitely wasn’t going to miss this. Once again he totally nailed it. In this talk he explored the controversial UEFI Secure Boot. You see, secure boot is a good thing, because it stops a computer whose boot has been compromised by a virus. The problem the free software community has with it is that there isn’t provisions for intentionally changing the boot image, (for instance when installing Linux). Other scenarios in different but comparable fields include Android phones who (sometimes) allow you change the boot image, but only if you turn off boot verification completely thus making a modified OS more vulnerable to attacks. Ideally there would be a way to self sign packages allowing them to boot without turning off secure boot. Here’s looking at you, hardware manufacturers. Watch to video here.

Programming Diversity by Ashe Dryden [ Video ] was not just about diversity with regards to women but other unrepresented people in the programming world too. This presentation was really well done, the slides were great and everything was referenced. This is my favorite quote from the talk and it really resonated with me because I’ve had this argument with people in the tech field way too many times that it is rather depressing so whenever I see someone championing diversity in the field I have a glisten of hope.

Then you might be thinking well “maybe women just aren’t biologically predisposed to programming”. You know maybe there’s just something in their brains that just makes them not good at programming, not good at writing algorithms or figuring this stuff out. There’s got to be, there has to be some kind of science to explain why we have this problem. But we actually do have science… in the exact opposite direction. There is no physical or biological difference that shows that anybody, regardless of their race or gender, is better at being a programmer. There is none. And a lot of the things that we talk about when we talk about things like evolutionary biology, which is what this question kind of hinges on, is the fact that you assume that there is some kind of addition that you get to being person for being a programmer. As if you can outrun a cheetah because you are a good programmer.

When I told people I was attending the talk, a surprising amount of people went down the whole evolutionary biology track almost as a knee jerk. I’d like to point any of my peers who feel like they agree with this line of thought to this post by a certain, Gentoo using lecturer who navigates his desktop solely via keyboard and writes all unit material in LaTeX.

From Kookaburra to the Cloud: where to now for copyright in Australia by Ben Powell [ Video ] was a very informative talk on the efforts to introduce a US style fair use to replace the current fair dealing. In summary (although I do recommend you watch the talk) fair dealing lists certain situations in which copyrighted material can be use without getting permission from the copyright holder, while fair dealing lists certain (usually four) factors which are weighed up against each other to decide whether or not the use of unlicensed copyrighted material was ‘fair’. The difference being that fair use is dealt with on a case by case basis which tends to keep up with the times more than fair dealing. For instance, one ludicrous example is that we are allowed to copy video from VHS to other devices but not DVDs. This kind of copyright law could allow court proceedings to reflect common sense instead of shoehorning outdated laws into current situations.

Below The Line: Fixing The Voting Process With Technology by Benno Rice [ Video ] followed Benno’s story of developing a web-app to try and combat the somewhat dirty tricks that candidates play in senate elections to try and get in by allowing people to preplan their below the line vote. I commend Benno for keeping his apolitical hat on throughout the entire process, thus strengthening democracy rather than strengthening a particular party. These kinds of talks frustrate me because while Benno has made a difference, I wish he didn’t have too. Clearly if somebody needs to make an unofficial web app in order to make our elections fair something is wrong and needs to be changed stat.

Disaster Recovery Lessons I Hoped I’d Never Have to Learn by Bdale Garbee [ Video ] made me and I think everybody else who saw it immediately evaluate our current backup procedure and almost certainly conclude it needs to be better. Seriously, watch it.

Finally I ended up at Introduction to Go by Mark Smith [ Video ] was an introduction to Google’s recently developed programming language Go. Having never used go, I’m pretty amazed at the fact that in the tutorial we made a multi-threaded chat program in about 45 lines. Go is a powerful language and as someone who hates locks/mutex management, I think I’m going to try learn some more. Another thing I like about Go is that the executable are completely self contained. Not having a interpreter or JVM needed is a real bonus when you might be distributing to someone who might not have them installed.

My linux.conf.au adventure is concluded here.

Linux.conf.au: Day 3

Wow. I now realise the last two days were just a warmup. The Conference really came into it’s own today. With talks going about twice as long as the previous two days, we really got some in-depth information from some top notch speakers.

This is a continuation of this post here about my first Linux.conf.au, here.

It started off with the lightning talks in lieu of a keynote speaker. I was a bit disappointed that there weren’t more of them (they finished well before scheduled) but the ones that were there were very well spoken about things ranging from Raising Geek Girls to Password Storage best-practices.

Next up I attended the Python 3: Making the Leap! by Tim Leslie tutorial. This was a great tutorial where Tim went through the nuances of the differences between the two versions of python and how the -3 flag and the 2to3.py tool can be used to convert a 2.xx script to python 3. I found this particularly helpful as someone who recent started having a go at python with my (disclaimer: linking to horrible, horrible code) blackboard scraper I recently wrote. For some reason despite all my dependencies working with python 3 I wrote it in 2.7. Learning to write pretty much depreciated code was probably not the most intelligent thing to do, but at least now I have a good explanation on what is different when writing code for 3 in the future.

Next up was Building Effective Alliances around the Trans-Pacific Partnership Agreement by Sky Croeser [ Video ]. The great thing about this talk is that it went beyond saying why the TPPA is bad, which is all we ever seem to hear from tech news sites, and actually delved into strategies of how to effectively combat. The strategies were diverse with no possibility left unturned, from writing letters to politicians to 1999 Seattle WTO Protest tactics – fun for the whole family! I thought the way she approached the topic was terrific, as a person who is not in the slightest bit interested in radical activism, but a strong interest in political issues such as this, it was nice to be acknowledged as somebody who can still contribute. If you’re at all worried about TPPA, I would strongly recommend watching the talk when it’s uploaded on Monday.

Bringing MoreWomen to Free and Open Source Software by Karen Sandler [ Video ] was a really eye opening talk on the strategies used at the GNOME Foundation the bring their amount of female contributors up to par with the rest of the Computing sector (3% compared to 18%, still a woefully small number). The lack of women in computing is quite a serious problem which I think is overlooked (and sometimes even perpetuated) by many computer scientists and programmers, and perhaps society in general. I’m fairly certain (and very hopeful) this is a changing statistic I’ve met many people who are committed to the issue.

Opening up government data by Pia Waugh [ Video ] continued from Monday’s open government miniconf about making government datasets available freely to the public. As I mentioned on Monday, Pia Waugh is definitely someone who is “on our side” in the government sector relating to open data and is in charge of the great data.gov.au website where you can request and vote for certain datasets to be release. She talked about certain issues related to open government data including ways to automate data collection and uploading (which would always provide up-to-date-data) and issues with the format in which data is provided. I love playing to datasets so this talk was very interesting to me, I would recommend giving it a watch when it’s online.

Reverse engineering vendor firmware drivers for little fun and no profit by Matthew Garrett [ Video ]* would have to be the best talk of the day (and possibly the week). In this talk we follow the protagonist Garrett as he embarks on a journey to reverse engineer a vendor tool for modifying servers which doesn’t quite go as expected. I won’t go any further because you have to watch it to really appreciate. The thing I really like about Garrett’s talk is not only the sprinkles of humor paced throughout, but the fact that whenever he says anything that isn’t basic computer/Linux knowledge, he stops and gives a short explanation of what that is. One mistake I feel like many speakers have is that they assume every attendee is as knowledgeable as they are in the domain they are speaking about when in reality there are people of all different types of skillsets. By not stopping to explain things you run the risk of having half your audience feel stupid and switch off. As a student these kinds of explanations are much appreciated and help me achieve my goal of learning more about the kernel.

*for those with a keen eye, you might notice that two Garrett and the Open Data talk overlapped. I watched one on video after the end of today’s conference.

That was all for today, looking very forward to tomorrow with a keynote by Matthew Garrett who will hopefully be beating his own record of “Best Talk so Far”. If you can’t make it but want to watch, tune in at http://timvideos.us/octagon at 9AM tomorrow.

My linux.conf.au adventure is continued here.

Linux.conf.au: Day 2

Continuing from this post here, I’m going to continue blogging my experiences at linux.conf.au being held this year in Perth and UWA as a newcomer.

I actually managed to make the keynotes for this day, which was Kate Chapman’s talk on OpenStreetMap [ Video ]. The cool thing about linux.conf.au is that everything is being livestreamed at timvideos.us so when I was a little late, I could still stream audio in the car. Sweet! The keynote was really warm and fuzzy about open source doing great things around the world using OpenStreetMaps. It was a very accessible talk and has even inspired me to eventually try to contribute to OSM in some way, which is what a talk should do!

I spent most of the day at the Kernel UnConference. I know nothing about the Linux kernel, my general kernel knowledge spans only what was taught in the introductory university course however I, like a bunch of other students attending from Curtin, want to know more about what drives our favorite OSes. Most of what was being said went over my head and at times it seemed like the participants were speaking another language but I still think I managed to get something out of it. I think the idea of UnConferences is really great and definitely improves audience engagement though.

During lunch a bunch of us decided to go to Cafe Biscotti for lunch. This is relevant because it’s the first cafe in Perth to accept Bitcoin. Ironically, it’s a tiny cafe situated on the ground floor of Bankwest, which is part of the largest banking group (Commonwealth Bank) in Australia. Props to them for being the trendsetter in Perth (and for giving a 5% discount).

Taken at Cafe Biscotti, 300 Murray St, Perth

Returning to the conference, I took a break from kernel hackerspeak to see A Pseudo-Random Talk on Entropy by Jim Cheetham. As an introduction to the history and current techniques for random number generation this talk was pretty good, however it was a bit short (at only ten minutes) and I would have loved a more in depth look. Such is life with the miniconfs though.

Finally returning to the Kernel UnConference after afternoon tea, I got to see the highlight of my day as a panel of kernel developers answered questions from the audience including Linus Torvalds. It’s really cool to have one of your idols talking nonchalantly a few meters away from you, and is something I’ll definitely remember this conference by.

Credit - Andrew Cooks — Credit – Andrew Cooks

My linux.conf.au adventure is continued here.

Linux.conf.au: Day 1

So today was the first day of my first Linux (or any) conference, linux.conf.au. Apparently blogging about these things is a thing (well at least according to Delan and Kye) so here we go.

Registrations were yesterday as well as the newcomer seminar about the conference by Rusty Russell (I hope this is his actual name.) who is a pretty cool guy and even bought all the newcomers a beer. We also got a whole bunch of merch which sadly didn’t include deodorant (see: Sysadmin miniconf) but was pretty decent for the $99 student ticket. We were also warned that the miniconfs over the first two days were independently run and could be a bit ‘rough’, as you’ll soon discover.

The first miniconf I attended was the Sysadmin miniconf where everyone was packed into the Woolnough lecture theater at UWA which is one of those ones where they try to cram as many seats into a room as possible. This combined with the hot Perth weather and a whole bunch of Linux enthusiasts did not make for a pleasant atmosphere to the point of where it was almost uncomfortable. To be honest, Sysadmin-ing bores me to tears and most of the talks either flew straight over my head or the speaker fumbled through slides, sometimes both. I feel like today’s miniconfs were slim pickings and I’m much more excited for tomorrow’s Open Programming conf. One gem in the rough for me was ‘Quality of Service’, a common misconception (10 mins) – Julien Goodwin [ Video ] one of the talks which I felt would be accessible to all of the audience and the speaker actually new his stuff, as someone who was tried to mess with QoS before studying CS, this ten minute talk made me understand it in a way that I previously hadn’t.

After getting sick of the Sysadmin conf I went to see the Open Government lightning talks and I wish I had gone their sooner. It was much less congested which really made it feel like more of a dialogue than the other talks. It was headed by Pia Waugh who seemed really passionate and knowledgeable about the subject (which you would hope she would be as the person in charge of data.gov.au, something I found out about today which I had never heard of and is amazing).

Lastly I went to a Crypto BoF (Birds of Feather, a concept which is new to me which I gather so far is a sort of informal discussion group). I’ve been a bit of a crypto enthusiast (Oh hey ASIO, I didn’t see you there) since doing some study on it at Curtin. One of the interesting topics which came up was the traditional security being at odds with usability and increasing usability may be a good thing regardless, because if enough people use PGP it may stop the people who use PGP from going on a list.

So that was linux.conf.au so far, it’s going to be an interesting week and I’m pumped for the proper talks to begin Wednesday-Friday. Hopefully I’ll be up in time for tomorrow’s keynote.

My linux.conf.au adventure is continued here.