I recently read Guidelines for future hypertext systems ( via ).Among other issues, I was sad but not surprised to see that it wassuggesting an idea for access control that is perpetually temptingto technical people. I'll quote it:

All byte spans are available to any user with a properaddress. However, they may be encrypted, and access control can beperformed via the distribution of keys for decrypting the content atparticular permanent addresses.

This is in practice a terrible and non-workable idea, because

When I wrote up what the Linux kernel's messages about segfaultingprograms mean , I described what wentinto the ' error N ' codes and how to work out what any particularone meant, but I didn't inventory them all. Rather than put myselfthrough reverse engineering what any particular error code means,I'm going to list them all here, in ascending order.

The basic kernel message looks like this:

testp[9282]: segfault at 0 ip 00000

I wrote earlier about how I planned to migrate my work Fedorasystem from MBT booting to UEFI booting once I moved to its new hardware , complete witha plan of what to do. Today I put that plan into action butunfortunately it didn't go well . I've nowreverted back to MBR booting and plan to stay on it for at leastthe lifetime of this hardware (probably at least five years). Hereis what happened, the various surprises I ran into, and what wentwrong.

For quite a while the Linux kernel has had an option to log a kernelmessage about every faulting user program ,and it probably defaults to on in your Linux distribution. I've seenthese messages fly by for years, but for reasons beyond the scope ofthis entry I've recently wanted to understand what they mean in somemoderate amount of detail.

I'll start with a straightforward and typical example, one that Isee every time I build and test Go (as this is a test case that

Recently, D. Ebdrup left a comment here asking a question about thebehavior of ZFS on 'advanced format' diskdrives with 4 Kbyte physical block (or sector) sizes. I figured I'dhave no problems answering it, since at this point I should haveany number of ZFS pools on such drives. Then I started actuallylooking for them.

For years, I've been strongly advocating that people should set upZFS pools as if they were on 4k sector advance format drives inorder to

Recently I found myself needing a Linux command that reported howmany CPUs are available for you to use. On Linux, the official wayto do this is to call sched_getaffinity andcount how many 1 bits are set in the CPU mask that you get back.My default tool for this sort of thing these days is Go and I foundsome convenient support for this (in the golang.org/x/sys/unixpackage ), so I wrote theobvious Go program:

package main

import (    "

As I wound up experimentally verifying ,in ZFS all files are stored as a single block of varying size upto the filesystem's recordsize , or using multiple recordsize blocks. If a file has more than one block, all blocks are recordsize ,no more and no less. If a file is a single block, the size of thisblock is based on how much data has been written to the file (ortechnically the maximum offset that's been written to the file).However,how the block

I wrote my first set of notes very earlyon in my usage of uMatrix, before things had really settled downand I mostly knew what I was doing it. Since then I've been refiningmy configuration and learning more about what works and how, andI've accumulated more stuff I want to record.

The first thing, the big thing, is that changing from NoScript touMatrix definitely seems to have mostly solved my Firefox memoryissues . My Firefox still slowly growsits memory usage over time, even

Today I tweeted :

I'm a little bit disappointed that the ASUS UEFI BIOS fetchesBIOS updates over HTTP instead of HTTPS (I'm sure they're signed,though). But thinking more about it, it's probably a sensible decisionon ASUS's part; there are a lot of potential issues with HTTPS in thefield.

Let's start with the background. I haven't been paying attentionto BIOSes for current hardware until recently and it turns out thatmodern UEFI BIOSes are