Linux related articles

  • Embedded,  Linux

    Adding a user space “power switch” to your embedded linux

    Is is always amazing to see how some very obvious features are missing from the linux kernel. Yesterday, for a project I am developing for a Dutch firm, I come across one of these “very obvious feature”: the option to switch on and off a device in the embedded linux board we’re using. The problem seemed to be quite frequent: you have a device connected to the internal USB bus (a wifi module, maybe?) and you want to switch it off completely when not in use. It is the only USB connection in that bus, a single power line is powering that device, and still you need to power the…

  • Embedded,  Linux,  uboot,  ubuntu

    Configuring Ubuntu to deal with an ARM board with U-Boot via USB

    Abstract We have a board on which an AllWinner ARM processor is running Linux. The bootloader is U-boot and we have to use the USB port to flash it. When flashing the device for the first time, after loading the bootloader via FEL protocol, we need to use tftp to load the SPL (Secondary program Loader) image and the uboot version for use with the spl. Unfortunately, a couple of issues in the default Ubuntu configuration prevent us from doing this apparently simple operation in a straight way, and we need to tweak some system configuration file. The issue After using the sunxi-fel tool to run the bootloader in memory,…

  • Linux,  vmware,  Windows

    Vmware Player is slow under Ubuntu 16 host, Part 2.

    So it seems the issue I talked about some week ago, wasn't fixed. Windows is still slow, the hard disk always working at 100% load. Not so slow, because the fix explained in my previous post seems to mitigate the problem, but still slow. Since I was using many Virtual Machines on that box without any problem since longtime, well before my upgrade to Ubuntu 16.04, I guessed the problem was the kernel. So I rolled back to 3.16. And… tada! now the machine works flawlessly. Seems incredible, because I looked around to see if anyone had similar issues, without any luck. So, if you're running kernel 4.4 and VmWare…

  • Linux,  vmware,  Windows

    Vmware Player is slow under Ubuntu 16 host

    So you just upgraded your Ubuntu box and found that all your VmWare Windows Boxes are extremely slow? The symptom is your Windows task manager showning 100% usage of your disk, and the WIndows Instrumentation showing very long lags, says, up to 2.5seconds (yes, seconds) to respond to a disk request. This makes the box practically unusable. Perhaps your vmware logs are shoing a lot of lines like scsi0:0: Command READ(10) took 2.748 seconds (ok) scsi0:0: Command WRITE(10) took 3.224 seconds (ok) and so on… Well, this is a well known issue. A quick search with google will point you to the vblank_mode=0 fix.  Indeed I already fixed that on my…

  • c++,  Code,  Linux,  Uncategorized

    The dbus-cpp Library, introduction

    While working on a bluetooth based embedded device, I needed to deal with the somehow infamous dbus. DBus and Bluez5 have a very steep learning curve, and if you are don't have access to either Qt framework or glib framework, you have indeed a problem. Glib are very complex C libraries that mimick some of the built-in feature of the C++ language, while on the other hand, Qt are very vast and sometime a big overkill. The stunning news is that it seems there aren't many options if you need a C++ only lightweight solution. It is not true, indeed. Somehow well hidden in the creases of the web, I…

  • Linux,  vmware

    Fixing problems with Ubuntu 13.04 and VmWare Tools

    Installing Ubuntu on my VmWare fusion box has never been so difficult as it was last weeks, when I needed to have it ready as soon as possible. Though 12.04 LTS has been proved to be a great choice when you need a solid rock linux box, latest Ubuntu boxes are preferable, on my opinion, for development purpose. This way, switching to the latest, bleeding edge kernel hasn’t gone well for the people at VmWare. There are two very big problems with the default installation. I usually choose the default installation because you only need the ubuntu ISO image and few minutes, and a new, shining linux box is ready…