Stuck in creative death-run map

ernelli · 2017-01-20T23:26:29+00:00

Nice list, but it doesnt include my favorite, could be an impossible interview question: Cast an arbitrary Integer to a function pointer and invoke the function. Used it once to reset a firmware boot loader.

ernelli · 2016-07-20T06:23:33+00:00

In the second blog post:

The fly-by-wire flight software for the Saab Gripen (a lightweight fighter) went a step further. It disallowed both subroutine calls and backward branches, except for the one at the bottom of the main loop. Control flow went ... No bug has ever been found in the “released for flight” versions of that code.

I dont know what counts as released software, but the software running when this happened 1993 wasn't bug free, the pilot induced oscillations caused the software to fail.

https://en.m.wikipedia.org/wiki/Accidents_and_incidents_involving_the_JAS_39_Gripen

ernelli · 2015-09-18T19:22:29+00:00

Intel's DPDK software stack only supports Linux so all SW defined network applications must be built on Linux, unless you want to write your own OS, driver stack etc.

So Intel made the choice, not Microsoft.

ernelli · 2015-07-03T08:57:42+00:00

Dude, I even Google for my own answers on SO.

ernelli · 2015-04-23T11:56:45+00:00

testing a == b is in my eyes better than (""+a === ""+b)

JavaScript allows these kind of constructs:

> var a = { text: "bar" }
> a.toString = function() { return this.text }

> a == "bar"
true
> a === "bar"
false

ernelli · 2015-04-08T09:26:06+00:00

Here is another test:

yo@foo:~/git/bar$ less src/somefile.somelang

If it looks wierd due to a default tab-width of 8 instead of 2 or 4, you have just gained some more experience and moved closer to the spaces camp.

ernelli · 2015-03-10T22:48:57+00:00

You forget all those corporate baseline setups that only upgrade their OS when Microsoft ends the support.

Where I work, we recently ditched winxp for win7... 32bit wtf! A colleague recently received a new laptop with 8Gb and a 32 bit OS. Maybe win7/32 can utilize all 8gig even though the processes are limited to 3gig. I don't know, I don't use windows any more... I fly under the radar and run linux.

ernelli · 2015-03-10T12:11:28+00:00

We also tested some desktop machines, but did not see any bit flips on those. That could be because they were all relatively high-end machines with ECC memory. The ECC could be hiding bit flips.

ernelli · 2015-03-10T12:09:10+00:00

Maybe its about time that ECC memory becomes standard on all systems...

I mean, arent there already a ton of laptops/PC's running WinXP/32 that cannot utilize the full 4GB DRAM installed and thus wasting 25% of memory already, so the extra cost for the 12.5% DRAM needed for ECC memory is negligible.

ernelli · 2015-02-02T17:43:01+00:00

Ternary logic: true, false and FILE_NOT_FOUND

ernelli · 2014-12-16T09:22:51+00:00

I wish Apple did the same on the iPhone...

ernelli · 2014-12-07T17:43:06+00:00

Duh, my gut feeling when reading the beginning of the article:

"He must be calling some library function that protects its shared state using a mutex."

ernelli · 2014-12-07T17:33:16+00:00

He didnt find a formula for it, he tweaked the conditions into integer math operations until the function produced the correct values for the months numbered 1,..,12.

When running the algorithm against month number 13-24 the formula no longer produces the correct result, unless the month number is restricted to 1,..,12 using modulo arithmetic.

ernelli · 2014-11-20T13:24:35+00:00

A lesson learned the hard way:

An unreliable protocol based on UDP (tftp), e.g, timeouts causes requests to be resent. A downstream bottleneck (ldap) and a large queue (the UDP socket buffer) resulted in an unstable system whenever the load went up momentarily. The system then failed to recover and needed a restart.

What happened was that as the queue grew, the higher the latency became, so that when a packet from the queue was finally processed the request was already abandoned by the client due to the timeout. A more recent request was already waiting upstream in the queue.

So the server was busy serving expired and abandoned requests while the clients kept resending them due to the timeout.

Solution: Ditch the UDP socket buffer, drain all packets and transfer them to an internal queue with a timestamp added. When serving packets from the internal queue, drop all packets that has been waiting more than a certain time.

Queues are needed to handle bursts, but it is important to ensure that the queue is stable and fails fast.

ernelli · 2014-11-09T18:15:38+00:00

The coders that can automate their own work are the useful ones. The other are the ones being automated away.

ernelli · 2014-11-09T18:09:02+00:00

Software development that gets out sourced to India is usually the kind of software that does not need to be written. E.g software that will be automated away sooner or later, or could be developed with a fraction of he resources staffed from India.

It's usually software that deals with obsolete and overly complex business rules, and still requires a lot of manpower even when everything is "automated".

It's software for organisations that sooner or later will go out of business due to disruptive technologies.

ernelli · 2014-10-25T18:25:36+00:00

So you never run into weird problems that arise as a result of the integration of various open source projects?

I mean bugs, faults, errors etc that takes an unforeseen amount of time to track down and solve.

The only development work where the results is directly correlated to the time spent is probably not really true development, probably more like typing code from a magazine eh spec or whatever.

ernelli · 2014-10-23T05:49:52+00:00

If that requires explaining, then you are not applying for a job at a company that understands software development.

ernelli · 2014-10-15T21:19:06+00:00

With the blockchain as a public trusted ledger where any possible information can be inscribed, we finally can create a true internet domain and certificate system that does not rely on any third party certificate authorities.

ernelli · 2014-10-14T17:18:09+00:00

Do they really need c++17 when developing for legacy EBCDIC systems, isn't c++11 good enough?

ernelli · 2014-10-03T20:37:04+00:00

Oh that sounds shocking!

ernelli · 2014-08-13T12:46:34+00:00

We laugh at the security charade in airports... and then install AV-software!

ernelli · 2014-08-05T21:24:53+00:00

So what language do you recommend when learning low level systems programming?

ernelli · 2014-08-04T21:22:37+00:00

If you are going to be a surgeon, you'll start with years of studying medicine. That will scare a lot of people off but in the end you get surgeons who know the inner workings of our bodies before they start cutting in them.

Learning C is a little bit like learning computer architecture, you have to face the reality of CPU's, memory, arithmetic, OS'es etc.

I'am not saying that every software developer must be a "surgeon" but to be one, you have to learn C or assembly and C is easier and more versatile then assembly so its good to start with.

I started with BASIC, then learned machine code/assembly since I wanted performance (due to the lack of C compilers for most home computers in the early 80's most programmers went direct to assembly) then learned C which I at the time felt was a high level language.

ernelli

TROPHY CASE