Thoughts dereferenced from the scratchpad noise.

Latest posts


Power on of ESP-12 (ESP8266)

Published at January 24, 2015 · Piotr Król ·  3 min read

ESP8266 is a SoC made by Espressif. For last couple of months this chip is a rockstar of HackADay and makers community around the Internet. Mostly because of WiFi modules built based on it (ESP-XX family). Rich interface (GPIO, SPI, SDIO, I2C) give those boards potential to be standalone MCU with WiFi capability for wide range of applications. In quantity you can get ESP-01 for $2.7 (for 1kpcs). Of course there is no free lunch....

Categories: firmware iot

Raspberry Pi kernel repository aggregating patches for Linux mainline

Published at October 15, 2014 · Piotr Król ·  3 min read

Since several months I’m trying to find my way to embedded Linux programming. My hardware set was very limited I had only one board that can be called “embedded” and it was Raspberry Pi. Because I am more interested in firmware/OS level then hardware I tried to figure out what is going on with RPi kernel. After taking brief review of raspberrypi/linux GitHub repository I realized that close to my heart is upstreaming effort....

Categories: os-dev

virtualbox-dkms: fix alloc_netdev problems when compiling with 3.17.0-rcX headers

Published at September 20, 2014 · Piotr Król ·  4 min read

Intro Because of my bug hunting approach of using latest kernel I experienced problem with compiling VirtualBox modules with 3.17.0-rc5 version on my Debian Jessie. Issue is well known and described for examples here. Problem manifest itself with: 1 2 3 4 5 6 7 8 9 10 11 12 ------------------------------ Deleting module version: 4.3.14 completely from the DKMS tree. ------------------------------ Done. Loading new virtualbox-4.3.14 DKMS files... Building only for 3....

Categories: app-dev

How to fix backlight issue on IdeaPad y510p

Published at August 23, 2014 · Piotr Król ·  1 min read

Today I decide to switch to latest kernel (3.17-rc1) on my IdeaPad y510p. I hit only one annoying problem until now - after booting my main screen was dimmed. I tried all instructions from top google hits for all possible configurations of keywords linux, y510p, backlight issue, etc. Especially I tried all methods from Arch Wiki. Finally I found solution, by greping modinfo for my Intel graphics card: 1 2 3 4 5 [23:55:24] pietrushnic:~ $ sudo modinfo i915|grep backlight parm: invert_brightness:Invert backlight brightness (-1 force normal, \ 0 machine defaults, 1 force inversion), please report PCI device ID, subsystem \ vendor and subsystem device ID to dri-devel@lists....

Categories: os-dev

Linux, RPi and USB over IP

Published at August 18, 2014 · Piotr Król ·  10 min read

Trying to google ‘USB over IP’ doesn’t give much except some business web pages that give you it as a service. This brings some information about potential on the market IMHO. Main idea is well presented on open source project page for usbip. I really recommend to read USB/IP - a Peripheral Bus Extension for Device Sharing over IP Network technical paper it describe briefly technical details and capability. In short USB over IP is a sharing system aim to expose USB devices from server to client encapsulating USB I/O messages in TCP/IP payload....

Categories: firmware

Coreboot for QEMU armv7 (vexpress-a9) emulated mainboard

Published at August 7, 2014 · Piotr Król ·  8 min read

Recently I came back to look into coreboot. Mainly because low level is fun and skills related to firmware (even coreboot) starting get attention on freelance portals (first odesk job, second odesk job). I was surprised that under the wings of Google coreboot team start to support ARM (BTW ARM programming is IMHO next great skill to learn). So I cloned latest, code compiled QEMU armv7 mainboard model and tried to kick it in latest qemu-system-arm....

Categories: firmware

Linux (Debian Wheezy) on Lenovo y510p

Published at May 16, 2014 · Piotr Król ·  4 min read

After long analysis I decide to buy new laptop. I had about $1000 (or 3000PLN) and most important things to me were: i7 CPU - because of performance (of course at least 4700 series) SSD - again performance 17.3” - working space no OS/FreeDos/Linux - I will not pay additional fee to M$ for system that I won’t use Full HD resolution at least 8GB RAM non-glare display First I realize that my budget is to small for such a hardware....

Categories: os-dev

Improve productivity with Google history using bookmarks and Chrome extensions

Published at July 30, 2013 · Piotr Król ·  5 min read

Statistics Depending on different factors we spend a lot of time in browser. I cannot find statistics for desktops but for mobile Flurry researches are probably relevant enough. Simplifying this statistics and assuming that desktop market is similar (it is probably to big simplification for some of you but IMHO it is good for reflections on this blog): access Facebook, social networks (+18%, +6%) play some games (lets say 30% of our 32% from Flurry report +13%) web browsing time (+20%) entertain read news use productivity tools We have at least 60 percent of our time in web browser....

Categories: miscellaneous

0x6: Root file system for embedded system

Published at June 7, 2013 · Piotr Król ·  10 min read

Table of contents Introduction Get and build BusyBox Fast and simple Setting up kernel through NFS Verify Configuration Embedded filesystem tuning Summary Introduction To make our embedded linux work as virtual development platform we need some environment after booting. There is many approaches to get working root file system but I will use the easiest one as an exercise. I don’t want to create full embedded distribution (this is good plan for future works)....

Categories: os-dev

0x5: Qemu network configuration and tftp for Virtual Development Board

Published at June 7, 2013 · Piotr Król ·  7 min read

Table of contents Introduction Setup tftpd QEMU networking Verify all components of Virtual Development Platform What next ? Introduction This was not trivial task to me. As usual google is your friend and RTFM works. First we will set tftp which we use to download modified kernel for U-Boot. Second I will show how to setup bridged network for QEMU needs and finally we will perform some basic test of our setup....

Categories: app-dev os-dev