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Showing posts from May, 2013

"has modification time x in the future" and Virtualization

If you are running Linux as a guest virtual machine on a Windows host (or some other OS) using VirtualBox, you might have encountered the following error when you try to compile something on the Linux guest:

make[2]: Warning: File `/media/sf_GitHub/misc/script_build/../../stack/lkm/ipstack.o' has modification time 0.51 s in the future

This happens when you try to build inside a folder shared from Windows using the VirtualBox Guest Extensions. There is a minute but detectable delay between the moment when gcc tries to write the intermediate .o file from inside the Linux guest and when it is actually written to the hard disk outside on the Windows host.

To get rid of the problem, just set the Linux guest's time 1 minute or so ahead of the time on Windows host.

Enabling kmemleak on Ubuntu i386 12.04.2 LTS by recompiling the kernel

While debugging a kernel module that we were developing, we wanted a kernel with some hacking options enabled, specially the kmemleak feature. Here is how we got that done. We were using Ubuntu i386 12.04.2 on a VirtualBox guest virtual machine running on a Windows 7 host.
Make sure you have atleast 7GB of free space on your system. While creating the VM, I set my disk size (dynamically expanding) to 20GB.Also make sure you do this on the latest Long Term Support (LTS) version of the Ubuntu supported at the time.Install VirtualBox Guest editions if using a VM so that it clipboard sharing is enabled making it easier for you to copy and paste command from the Host OS to Guest OS.Update the system. This is essential as you need the very latest collection of userpace programs, kernel, and userspace-kernelspace libraries which are know to correctly work together at the time you try this. This is necessary becuase when you download the kernel sources, it will be of the latest kernel which s…

The Europlug epidemic in India

A major quantity of electrical/electronic equipment imported into India have a Europlug. The Europlug fits poorly in many Indian style 3-pin sockets. Here is the analysis of the situation. Suggested solution involves using an appropriate converter.