(More than) Everything you always wanted to know about...

Marcos Dione — Fri, 14 Nov 2025 21:36:59 GMT

From time to time you need to deep dive into a subject and you need a good site to read about it. Over the years I have come across many such sites, and this is my attempt to collect them in a single place. I have revisited the some of the same subjects, but since searching the web has become a worse and worse experience, finding them again has been almost impossible.

I hope to make this list as long as all the sites I want to put here. Also, I'll be using Archive.org's links, to make sure you can find them even if the sites are down.

Certificates and CAs

https://jamielinux.com/docs/openssl-certificate-authority/

Linux memory

https://blogs.oracle.com/linux/understanding-linux-kernel-memory-statistics

UEFI

https://www.happyassassin.net/posts/2014/01/25/uefi-boot-how-does-that-actually-work-then/

Bikes

https://www.sheldonbrown.com/

Sound

[PulseAudio][https://gavv.net/articles/pulseaudio-under-the-hood/]

Defining reserved space in blocks vs percentage

Marcos Dione — Sun, 27 Jul 2025 10:46:30 GMT

A quick one.

Many (most?) filesystems in Linux can define reserved space. This is space that only the superuser can write to, and it's usually reserved for times when you've run out of space, allowing the super user to still operate the computer, even when normal users can't write anymore. This is also why there is the concept of available vs free space in partitions.

Historically, reserved space was defined in percentage. But with bigger and bigger disks (30TB now?), even 1% is a a lot of space (300GB). Fortunately, we can also define it in blocks. At 4KiB per block, you can reserve "only" 1TiB with:

tune2fs -r $((1024 * 1024 / 4)) [partition]

Unluckily, many of these tools don't define --long-options.