Geekish things: kexec and BRLCAD

[unixronin]

The kexec() call has existed in the Linux kernel for some time.  I just yesterday got around to installing and setting up kexec-tools and experimenting with kexec().  I'd hoped it would enable me to switch to a new kernel without having to actually reboot, inheriting all the existing kernel structures and data, but (not surprisingly) that turns out to be a bit much to ask.  What it DOES do, however, is dramatically speed up rebooting by skipping the entire BIOS initialization phase.  After umounting everything and stopping all processes, instead of going on to cold-boot the machine from scratch, the kexec daemon jumps directly to warm-booting the new kernel.  On babylon5, this turns out to shorten the reboot time by almost two minutes.

Sure, two minutes isn't much in the overall scheme of things.  But it feels like eternity when you're sitting there twiddling your thumbs while you wait for the machine to reboot.  It also appears kexec() consistently reboots my laptop, which — if rebooted without kexec — will as often as not decide to just shut itself down instead.

In other geekish pursuits, I got BRLCAD installed over the weekend, and spent a fair bit of time learning the basics.  (I observe that BRLCAD's raytracer doesn't anti-alias edges very well.)

Here's my take on the mug tutorial, and my version of the candle tutorial, rather more elaborate than the USARL's...:

---

Comments

rt doesn't do anti-aliasing

[https://me.yahoo.com/brlcad#97794]

BRL-CAD's "rt" ray tracer doesn't implement anti-aliasing. The options for hypersampling (-H) and jitter (-j) do not perform blending for a variety of reasons. There is rudimentary support for anti-aliasing with BRL-CAD's "rtedge" ray tracer, but the best practice approach still recommended to users is to render at 2x (or bigger) and downsample. This of course increases render time but generally gives much better control on the type of anti-aliasing performed.

Great shots of your BRL-CAD tutorial geometry. Hope you'll take it to the next step and model something of your own choosing.. either way, thanks for the write-up. Cheers!

Re: rt doesn't do anti-aliasing

[unixronin]

Yup, I tried to get some edge anti-aliasing using hypersampling and jitter, but it really didn't work very well. Next time I'll try the down-sampling route. And yes, I'm going through the tutorial strictly to learn the tools. I also tried to simulate a wood grain on the tabletop using the camo shader, but its fine points elude me. I suspect what I probably should be using there is a texture map or a bump map, but so far I haven't found enough detailed documentation to figure out how to use those.

The first real project I expect to use it for is to model a complete redesign of my desk.