http://www.embedded-bits.co.uk Understanding the embedded world bit by bit Tue, 16 Aug 2011 21:42:28 +0000 en hourly 1 http://wordpress.org/?v=3.2.1 http://www.embedded-bits.co.uk/2011/vmalloc-region-overlap/ http://www.embedded-bits.co.uk/2011/vmalloc-region-overlap/#comments Tue, 16 Aug 2011 21:42:28 +0000 Andrew Murray http://www.embedded-bits.co.uk/?p=972 I recently came across the following disconcerting message in my kernel’s boot output: Truncating RAM at 40000000-5fffffff to -57ffffff (vmalloc region overlap). ... Kernel command line: console=ttySC0,115200 mem=512M ... Memory: 384MB = 384MB total Which is the kernel’s way of saying “I understand there may be some RAM here – but I’m not going to [...]]]> http://www.embedded-bits.co.uk/2011/vmalloc-region-overlap/feed/ 0 http://www.embedded-bits.co.uk/2011/string-bug-in-c/ http://www.embedded-bits.co.uk/2011/string-bug-in-c/#comments Sun, 07 Aug 2011 20:14:21 +0000 Francesco Balducci http://www.embedded-bits.co.uk/?p=936 Today I encountered a bug that was quite difficult to find regarding strings. In order for strings to work they must be null-terminated, and this implies that an array of characters can contain a string with a length equal to the array size minus one, because there must be space for the null character. I [...]]]> http://www.embedded-bits.co.uk/2011/string-bug-in-c/feed/ 1 http://www.embedded-bits.co.uk/2011/twitter/ http://www.embedded-bits.co.uk/2011/twitter/#comments Sun, 07 Aug 2011 15:04:50 +0000 Andrew Murray http://www.embedded-bits.co.uk/?p=903 Embedded-bits.co.uk has joined Twitter! I thought it would be a great way to get to know my readers and to share with you the blog posts I write. When it comes to developing for embedded devices – it can be quite difficult to find good documentation or informative articles on the things we really need [...]]]> http://www.embedded-bits.co.uk/2011/twitter/feed/ 0 http://www.embedded-bits.co.uk/2011/mmucode/ http://www.embedded-bits.co.uk/2011/mmucode/#comments Wed, 27 Jul 2011 20:04:42 +0000 Andrew Murray http://www.embedded-bits.co.uk/?p=827 In my last post we looked at the basic theory of an MMU and what it can do for us. In this post we are going to produce and understand the absolute minimum amount of code required (just 20 lines of assembler) to turn on an ARM MMU and come out the other side in [...]]]> http://www.embedded-bits.co.uk/2011/mmucode/feed/ 5 http://www.embedded-bits.co.uk/2011/mmutheory/ http://www.embedded-bits.co.uk/2011/mmutheory/#comments Sun, 24 Jul 2011 11:54:51 +0000 Andrew Murray http://www.embedded-bits.co.uk/?p=705 In my last post I wrote some bare metal code which ran on a BeagleBoard xM as an MLO – I’d like to extend this by running this code with the MMU switched on. I want to write the absolute minimum amount of code required to turn on an ARM MMU and to come out [...]]]> http://www.embedded-bits.co.uk/2011/mmutheory/feed/ 1 http://www.embedded-bits.co.uk/2011/contributorswante/ http://www.embedded-bits.co.uk/2011/contributorswante/#comments Sat, 23 Jul 2011 09:51:57 +0000 Andrew Murray http://www.embedded-bits.co.uk/?p=720 To improve the broadness and frequency of articles on this site – I’m looking for contributors willing to write blog posts for embedded-bits.co.uk. I believe this will make the site a much more attractive place on the internet and a more useful resource for those in interested in our field. If you are a systems [...]]]> http://www.embedded-bits.co.uk/2011/contributorswante/feed/ 0 http://www.embedded-bits.co.uk/2011/writeanmlo/ http://www.embedded-bits.co.uk/2011/writeanmlo/#comments Sun, 10 Jul 2011 17:53:10 +0000 Andrew Murray http://www.embedded-bits.co.uk/?p=636 Before I started playing with the BeagleBoard XM I’ve had never booted a board directly from an MMC card and I didn’t have a clue what an ‘MLO’ file was. After some research on the internet it seemed apparent that it was used in place of the traditional first stage boot loader: XLoader. In fact [...]]]> http://www.embedded-bits.co.uk/2011/writeanmlo/feed/ 4 http://www.embedded-bits.co.uk/2011/beagleboardxmjtagsoftware/ http://www.embedded-bits.co.uk/2011/beagleboardxmjtagsoftware/#comments Sun, 10 Jul 2011 13:58:02 +0000 Andrew Murray http://www.embedded-bits.co.uk/?p=599 In my last blog post I described my rationale for buying a BeagleBoard XM and a compatible JTAG emulator – the XDS100v2. This post follows on from that and describes the steps required for setting up TI’s Code Composer Studio such that you can use the XDS100v2 with the BeagleBoard XM to find out what [...]]]> http://www.embedded-bits.co.uk/2011/beagleboardxmjtagsoftware/feed/ 4 http://www.embedded-bits.co.uk/2011/beagleboardxmjtaghardwar/ http://www.embedded-bits.co.uk/2011/beagleboardxmjtaghardwar/#comments Sun, 10 Jul 2011 09:47:13 +0000 Andrew Murray http://www.embedded-bits.co.uk/?p=538 I recently decided to embark on writing my own C++ real-time operating system for embedded systems – I’ve so far made some progress using software emulation with QEMU but I feel it’s time to move on to real hardware. I’ve chosen to use the very popular BeagleBoard XM – mostly because it represents incredible value [...]]]> http://www.embedded-bits.co.uk/2011/beagleboardxmjtaghardwar/feed/ 5 http://www.embedded-bits.co.uk/2011/right-approach-to-minimal-boot-times/ http://www.embedded-bits.co.uk/2011/right-approach-to-minimal-boot-times/#comments Sun, 20 Mar 2011 09:52:49 +0000 Andrew Murray http://www.embedded-bits.co.uk/?p=515 Last year at the ELCE 2010 conference in Cambridge I performed a talk about reducing boot times of embedded Linux devices. The video of this talk has now been posted on-line: ELCE 2010 – The Right Approach to Minimal Boot Times ELCE Video (Best viewed in Chrome) If you wish to see the accompanying slides [...]]]> http://www.embedded-bits.co.uk/2011/right-approach-to-minimal-boot-times/feed/ 0