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Revisiting the DOS memory models

At the beginning of the year, I wrote a bunch of articles on the various tricks DOS played to overcome the tight memory limits of x86's real mode. There was one question that came up and remained unanswered: what were the various models that the compilers of the day offered?

Tiny, small, medium, compact, large, huge... What did these options mean? What were their effects? And, more importantly... is any of that legacy relevant today in the world of 64-bit machines and gigabytes of RAM? To answer those questions, we must start with a brief review of the 8086 architecture and the binary formats supported by DOS.

September 30, 2024 · Tags: blogsystem5, dos
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Windows NT vs. Unix: A design comparison

Over the years, I’ve repeatedly heard that Windows NT is a very advanced operating system and, being a Unix person myself, it has bothered me to not know why. I’ve been meaning to answer this question for years and I can do so now, which means I want to present you my findings. My desire to know about NT’s internals started in 2006 when I applied to the Google Summer of Code program to develop Boost.

September 9, 2024 · Tags: blogsystem5, unix, windows
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Picking glibc versions at runtime

In a recent work discussion, I came across an argument that didn’t sound quite right. The claim was that we needed to set up containers in our developer machines in order to run tests against a modern glibc. The justifications were that using LD_LIBRARY_PATH to load a different glibc didn’t work and statically linking glibc wasn’t possible either. But… running a program against a version of glibc that’s different from the one installed on the system seems like a pretty standard requirement, doesn’t it?

August 11, 2024 · Tags: blogsystem5, programming, unix
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Kyua graduates

After years of inactivity, the Kyua project has graduated as an open source citizen and has under the FreeBSD umbrella!

But uh… wait, what is Kyua and why is this exciting? To resolve confusion and celebrate this milestone, I’d like to revisit what Kyua is, how it came to be, why I stopped working on it for a while, why that was a problem for FreeBSD—and, indirectly, NetBSD—and how Kyua being free software has helped keep it alive.

August 2, 2024 · Tags: blogsystem5, freebsd, kyua, netbsd
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Rust doesn't solve the CrowdStrike outage

Look, I like Rust. I really, really do, and I agree with the premise that memory-unsafe languages like C++ should not be used anymore. But claiming that Rust would have prevented the massive outage that the world went through last Friday is misleading and actively harmful to Rust’s evangelism.

Having CrowdStrike written in Rust would have minimized the chances of the outage happening, but not resolved the root cause that allowed the outage to happen in the first place. Thus, it irks me to see various folks blanket-claiming that Rust is the answer. It’s not, and pushing this agenda hurts Rust’s adoption more than it helps: C++ experts can understand the root cause and see that this claim is misleading, causing further divide in the systems programming world.

So, why won’t Rust help? Let me try to answer that question, but while we are at it, let’s also delve deeper into the causes of the outage. In a way, let me put my SRE hat on and write my own version of the postmortem.

July 23, 2024 · Tags: blogsystem5, opinion, rust
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20 years of blogging

Blog System/5 hasn’t always been called this way and it hasn’t been my first experience with blogging either. In fact, today marks the 20th anniversary of this publication in its various incarnations so it’s time for a bit of reflection. Just to set context for when 20 years ago was: Windows XP was almost 3 years old, Ubuntu had just debuted, Apple computers were still PowerPC-based, Half Life 2 was about to launch, and Slashdot was the place to be instead of the yet-to-be-created Hacker News.

June 22, 2024 · Tags: blog, blogsystem5
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Porting the EndBASIC console to an LCD

Hello again Blog System/5 and sorry for the radio silence for the last couple of months. I had been writing too much in here and neglecting my side projects so I needed to get back to them. And now that I’ve made significant progress on cool new features for EndBASIC, it’s time to write about them a little! One of the defining characteristics of EndBASIC is its hybrid console: what looks like a simple text terminal at first glance can actually render overlapping graphics and text at the same time.

April 26, 2024 · Tags: blogsystem5, endbasic, rust
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How "new type" helps avoid production outages

My January links recap included the “Phantom Types” article by David Soria Parra. In it, the author briefly touches upon the “new type” idiom, its typical implementation in Rust, and then proceeds to propose a better alternative. But the question arises: why should you care? To answer why this idiom is useful, I want to present you with a real production problem we faced in the Storage Infrastructure team at Google circa 2010.

March 9, 2024 · Tags: blogsystem5, rust, sre, twitter-thread
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Links: February 2024 edition

Hi folks! Another month has passed so it’s time for a brief recap of the main news, articles, and projects that made the rounds during this period and are on topic for Blog System/5. As usual, this is not just a list: every entry is accompanied by a short blurb detailing why I found the content interesting, which is meant to nudge you into reading it! Also, the list is ordered by when the links made it my way, not chronologically, and some items are not from this time period.

February 29, 2024 · Tags: blogsystem5, recap
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To C or not to C

Over the last few days, there has been this… debate over at Twitter sparked by a claim that you cannot be a good programmer without knowing C. You obviously can be one, but there is some nuance in what “knowing” C is truly about. Here is my take on the matter. Let me repeat this first: of course you can be a perfectly good programmer without knowing C. Knowing a language doesn’t make or break a programmer, and there are great programmers out there that don’t touch C.

February 21, 2024 · Tags: blogsystem5, opinion, programming, twitter-thread
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