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Fourthdwarf

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About Fourthdwarf

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  1. Fourthdwarf

    Programming - GPU intensive things?

    I'm unfamiliar with any implementation of ray tracing that works purely by operating on an acyclic graph. I can see the argument that you produce a DAG in 3D space, but that's not a graph problem. RTX does use octrees, but it has specific hardware to accelerate those octrees, and this only accelerates raytracing (by culling objects) AFAIK. And BSP is also used to similar effect. But in both cases, you have acyclic graphs with relatively few edges, as opposed to well connected graphs with cycles, that may cause issues. Also, it's only relatively recently that GPUs have outperformed CPUs in raytracing, partly because detecting intersections is difficult without breaking uniform control flow. So yeah, some graph algorithms do work well on GPUs, but add cycles, backtracking, and other common graph algorithm issues or techniques, and you have something possibly much less suited to GPUs. GPUs might find a small advantage here, but nothing near what other kinds of problems can have.
  2. Fourthdwarf

    Programming - GPU intensive things?

    Are you sure? With graph theoretic algorithms you might need non-uniform control flow, which is a big no-no on GPUs. Which is something others have brushed past, but its hecka important. For efficiencies sake, you need every invocation* to have the same control flow, because every invocation will take every path. * An invocation is like a thread, but per work-item (in a graphical setting, these may be vertices or pixels, in GPGPU, these can be anything)
  3. Fourthdwarf

    Has anybody thought about making an operating system?

    Take a leaf out of apples book and don't start from scratch. Start with, say, L4, which is probably the most successful modern microkernel, and build your own services etcetera. If you use L4Linux as a basis, you can possibly treat L4 like an exokernel, having the features of Linux (though running in userspace) alongside a microkernel API allowing access closer to the metal. You might need to build an arcane X11 setup if you go for this option, but it would be nothing on starting from scratch on modern hardware, which is the result of 50 decades of workarounds. I like the Idea though. Personally, I'd like to do a huge refactor of Linux to build a microkernel OS, or split L4Linux into multiple services, but that'd be a full time job.
  4. Fourthdwarf

    Kali Linux WiFi not working :(

    More properly: Run Kali in a VM, not directly on hardware! It's primarily a set of tools, and not a useful OS!
  5. Fourthdwarf

    Renewable Energy... Where Do I Start? :)

    So, it turns out, that at a small scale, it's cheaper to go solar, because it requires less engineering. On my favourite electronic component supply website I can get panels at £3/W, whereas the cheapest motors come in at around £5-£10, and have a built in gearbox which may help or hinder your project. And an AC motor, which produces a nicer waveform, costs at least £30. And then, you need the actual turbine blades! While you could build a William Kamkwamba style turbine, it might not win favour with a HOA. You'll possibly end up 3D printing it. Oh, and a housing. These costs add up. Meanwhile, on the solar project, we're already at the power conditioning stage. Once again, solar comes out on top, since we'll likely be using DC-DC conversion, with a relatively stable signal. Output 5v to charge a phone, or whatever. On the wind side, we'd need much better power conditioning, as DC motors are noisy, and an AC motor won't produces a useful waveform either. You'd need to do either AC-DC conversion, or AC-AC conversion, both of which are more complicated than DC-DC regulation. AC-DC conversion needs a bridge rectifier, and some smoothing circuitry to ensure a nice flat DC signal. AC-AC conversion is even more difficult. This is because you have your input signal, which is within some range of frequencies, and then you need to convert it into a specific frequency. For a hobbyist, perhaps you'd choose a motor-generator set - tripling the cost of the motors (at least)! TL:DR Solar is cheaper to build at small scales, if you have access to the internet.
  6. Fourthdwarf

    GPU instruction sets?

    SPIR-V - the fifth iteration of SPIR - is an important (and cross platform) assembly like language for GPUs. It allows for the front end of the compilation process to be done ahead of time, and with a single front end. Vulkan no longer requires opengl. Instead, it uses SPIR-V. The shaders are compiled to SPIR-V. And these shaders (in theory) will work on any platform with vulkan support, be it a PC with an Radeon VII, a Nintendo Switch with it's nVidia Tegra GPU, or a smartphone with a Mali or Adreno GPU. It can even be used when developing for iOS and macOS, although it will have to be converted into MSL, using tools like those in MoltenVK.
  7. Fourthdwarf

    Overclocking a Texas Instruments 83

    Cooling this kind of processor too much will just increase the resistivity of the silicon, making the critical path (length of a clock cycle) longer. They just don't put out enough heat for cooling to be the bottleneck.
  8. Have the game and the file owned by another user to the actual user, and the game changes the permissions of the file. Let's say we have users user - the actual intended user gamer - the owner of certain files and files -rws--x--x gamer gamer 34927 Jul 30 17:50 snake -rw------- gamer gamer 1268 Jul 30 17:48 secret The snake binary is setuid gamer, so when it runs, it runs as gamer. This means that the snake program can change the permissions for secret (perhaps to -rw-r--r--). However, due to permissions, user cannot change the permissions for secret.
  9. Fourthdwarf

    Programing "OS" for set top box

    It looks like all the software is released under GPL v2 or more permissive licenses. This means that Samsung were obliged to give you access to the source code if asked, but they are under no obligation to help or allow you to easily modify the software on the actual device (the GPLv3 has a 'tivoisation' clause that gives that obligation, but any GPLv3 software was likely avoided because of this) TL;DR It's unlikely you'll be able to do anything without using security exploits.
  10. Fourthdwarf

    [HELP] Photovoltalics

    So, a solar panel is basically a diode - It only allows electrons to go one way. The photons knock the electrons in any direction, but as they can only go one way across the diode, you get a net forward current. (An LED is basically the same but backwards - in theory you can use them interchangably, but in reality they are optimised for different tasks)
  11. Fourthdwarf

    DIY smart glasses

    If you want a cheap, small display, there is the possibility you could use the display from a digital camcorder viewfinder. It's only really practical for CRT based viewfinders, which are very long, and use very high voltages. Do not do this unless you are absolutely certain that you know how to deal with high voltages and all the other risks! It is a really dumb idea and not really practical anyway!
  12. If there is support for it, it will likely be part of fprint (package libpam_fprint), which is a PAM module (authentication module).
  13. Fourthdwarf

    OS change for kindle

    For a kindle, there isn't much in the way of alternative OSes, especially for self described noobs. The stock operating system uses linux/busybox, with alsa. An X server can be installed on some versions, depending on the firmware version. This is done by installing Arch ARM in a chroot jail. This gives access to all the packages available for arch ARM. A gentoo or debian chroot might also be possible. tl;dr Not really possible, modification is viable iff you know what you are doing.
  14. Fourthdwarf

    Raspberry Pi Model Confusion

    There's some confusion in this thread. Let's look at the models in chronological order: Model B: the first version manufactured. 800mhz single core armv6, with 256mb of ram, 2 USB ports, sdcard slot and an Ethernet port. $35 Model B rev.2: 800mhz, with 512mb ram. Same dual USB + Ethernet. $35 Model A: 800mhz, 256 mb, one USB, no Ethernet. $25 Model B+: new circuit board with rounded corners and 4 USB ports. Same "form factor" as pi 2/pi3. Uses microSD slot. $35 Compute module: 800mhz, 512mb ram 4gb flash. sodimm form factor. No sdcard slot. $30 Pi 2: quad 900mhz armv7 processor, 1gb of ram. $35 Pi zero: microHDMI, microSD and micro USB. Over clocked 1GHz single core processor. 512mb ram. $5 Pi 3: 1.2ghz quad core. WiFi& Bluetooth. 1GB ram. $35 Pi compute module 3: 1.2ghz quad core sodimm. 1gb ram, 4gb flash $35 Pi compute module 3L: 1.2GHZ quad core, 1gb ram, microSD slot. $25 Custom raspberry pi: Pi1/2/3/compute module with options for touchscreen, more ram, wireless & PoE. Minimum order quantity 1000, price on application.
  15. Fourthdwarf

    Arch Linux Questions

    feh --bg-fill /path/to/image. You can put it into your .xinitrc to do this permanently, or even stick a little background loop in which picks a random one every few minutes. You can get icons in i3 using i3-wm-iconpatch from the AUR, or you could even switch out i3-bar for something like lemonbar or lxpanel/xfcepanel, which can do macOS style stuff quite easily. WPA_GUI is a ok for setting up wifi if wifi-menu isn't enough for you. For the AUR, it's probably best to use a download helper, so you can more easily update when necessary. (I use packer).
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