Jean-Luc Aufranc (CNXSoft), Author at CNX Software - Embedded Systems News

July 28, 2010May 12, 2018 by Jean-Luc Aufranc (CNXSoft) - No Comments

Enabling swap in embedded systems

If your embedded system running Linux does not have enough memory, you can enable swap to get more memory. However if your platform does not have MMU (Memory Management Unit) as is the case for Sigma Designs EM8620 series, it won’t support swap, so forget it. If your platform does have MMU, as is the case for many newer platforms such as Sigma Designs SMP8630, SMP8640 and SMP8650 series, you can enable swap support. First you’ll have to make sure swap support is enabled in your kernel:

CONFIG_SWAP=y
CONFIG_SWAP_PREFETCH=y

1 2	CONFIG_SWAP=y CONFIG_SWAP_PREFETCH=y

and swapon/swapoff is enabled in busybox. So for example if you have an IDE harddisk with the second partition configured as swap. (Use fdisk to create a partition and mkswap /dev/hda2 to initialize the partition), you can enable the swap as follows:

swapon /dev/hda2

1	swapon /dev/hda2

If you get out-of-memory killer kernel error, you can change the “swapiness” to avoid oom-killer to kick in.

echo 0 &gt; /proc/sys/vm/mapped

1	echo 0 > /proc/sys/vm/mapped

[…]

July 25, 2010July 17, 2012 by Jean-Luc Aufranc (CNXSoft) - No Comments

How to Generate CVS Changelog Automatically

There is a perl script called cvs2cl.pl provided by Red-Bean You can get the latest version thru cvs: cvs -d :pserver:anonymous@cvs.red-bean.com:/usr/local/cvs co cvs2cl/cvs2cl.pl Copy the script in a directory that belong to the path e.g.: cp cvs2cl.pl /usr/local/bin Then just checkout your project and run cvs2cl.pl to generate a ChangeLog that will look like: 2010-01-18 developer1 * app/cnxapp/Makefile: Added support for SMP8652 target 2010-01-17 developer2 * app/cnxapp/cnx_download.c: Added HTTP resume support [Bug 1250]: Fixed potential buffer overflow … where developer1 and developer2 are the linux usernames of the developers, app/cnxapp/Makefile, app/cnxapp/cnx_download.c the files that have been modified, and the comments correspond to the messages input during cvs commit. cvs2cl.pl also have other options such as XML output, date selection etc… Just type cvs2cl.pl –help to get the full options. Jean-Luc Aufranc (CNXSoft)Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, […]

July 21, 2010July 17, 2012 by Jean-Luc Aufranc (CNXSoft) - No Comments

Block CVS Commits without message

If you are in my case, and you found it difficult to make some people in your team make proper comments/messages or any comments at all (cvs commit -m “Description of the changes”) while committing their changes to CVS, here’s what can be done to block commit without comments and with short comments. Checkout the CVSROOT directory cvs co CVSROOT Edit verifymsg in CVSROOT as follows #Set the verifymsg file to run a script DEFAULT /usr/local/bin/validate-cvs-log.sh Create /usr/local/bin/validate-cvs-log.sh script (make it executable for all cvs users): #!/bin/sh # # validate-cvs-log.sh logfile # test that log message has some characters in it if [ cat $1 | wc -c -lt 12 ] ; then echo “log message too short; please enter a description for the changes” exit 1 else exit 0 fi Commit verifymsg cvs commit -m “Added script to set minimum message size to 12 characters” verifymsg That’s it ! […]

July 18, 2010December 20, 2016 by Jean-Luc Aufranc (CNXSoft) - 9 Comments

How to do a framebuffer screenshot

I’ll explain how to do framebuffer screenshots on 16-bit and 32-bit framebuffer. For 16-bit this is fully based on http://docs.blackfin.uclinux.org/doku.php?id=framebuffer Capturing screenshots Whatever the bit-depth of your framebuffer, the first step is to capture the frambuffer raw data on the board:

cat /dev/fb0 > screen.raw

1	cat /dev/fb0 > screen.raw

Now the you need to take the raw image, and convert it to a standard image format. This step depends on what type of display is there Converting 16-bit Framebuffer screenshot (RGB565) into png To convert the raw rgb data extracted from /dev/fb0, use iraw2png perl script

#!/usr/bin/perl -w

$w = shift || 240;
$h = shift || 320;
$pixels = $w * $h;

open OUT, "|pnmtopng" or die "Can't pipe pnmtopng: $!\n";

printf OUT "P6%d %d\n255\n", $w, $h;

while ((read STDIN, $raw, 2) and $pixels--) {
   $short = unpack('S', $raw);
   print OUT pack("C3",
      ($short & 0xf800) >> 8,
      ($short & 0x7e0) >> 3,
      ($short & 0x1f) << 3);
}

close OUT;

#!/usr/bin/perl -w

$w = shift || 240;

$h = shift || 320;

$pixels = $w * $h;

open OUT, "|pnmtopng" or die "Can't pipe pnmtopng: $!\n";

printf OUT "P6%d %d\n255\n", $w, $h;

while ((read STDIN, $raw, 2) and $pixels--) {

$short = unpack('S', $raw);

print OUT pack("C3",

($short & 0xf800) >> 8,

($short & 0x7e0) >> 3,

($short & 0x1f) << 3);

}

close OUT;

To do the conversion, type the following command in the host:

./iraw2png 640 480 < screen.raw > screen.png

1	./iraw2png 640 480 < screen.raw > screen.png

where 640 and 480 are respectively the width and height of your framebuffer. This has been tried on a 16-bit framebuffer on EM8620 series. Converting 32-bit Framebuffer screenshot (ARGB, RGBA, BGRA…) into png The solution proposed here is not as neat as the blackfin’s solution for 16-bit framebuffer, […]

July 14, 2010October 15, 2019 by Jean-Luc Aufranc (CNXSoft) - No Comments

Yet Another Android Tablet by Foxconn

Here’s a video of another Android tablet, a 10″ tablet made by Foxconn, aka Hon Hai Precision Industry Company. There seems to be quite a few tablets coming on the market (See Allgo Tablet) that should keep the prices down. Jean-Luc Aufranc (CNXSoft)Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011. www.cnx-software.com

July 11, 2010November 24, 2019 by Jean-Luc Aufranc (CNXSoft) - No Comments

uClinux kernel panic: Stack overflow

If you’re using ucLinux, you may get kernel panic errors coming out of nowhere. There may be several reasons (buffer overflow, out of memory..), but the most common is stack overflow for the process or one of the threads. To increase the stack size of a flat binary you’ll need to adjust the LDFLAGS as follows:

LDFLAGS+=-Wl,-elf2flt="-s65536"

1	LDFLAGS+=-Wl,-elf2flt="-s65536"

This will set the stack size to 64KB. To change the stack size of a thread (e.g. 32KB below), you’ll need to set the stack size attribute:

pthread_attr_init(&attr);
err = pthread_attr_setstacksize(&attr, 32*1024);
if (err) {
    printf("pthread_attr_setstacksize returned non-zero: %s\n",
    strerror(errno));
}
err = pthread_create(&pthThread, &attr, thread, NULL);

pthread_attr_init(&attr);

err = pthread_attr_setstacksize(&attr, 32*1024);

if (err) {

printf("pthread_attr_setstacksize returned non-zero: %s\n",

strerror(errno));

}

err = pthread_create(&pthThread, &attr, thread, NULL);

How to detect which thread suffers from stack overflow? First, you can check your code for recursive function calls and local variables (especially arrays) both of which will be added at runtime to the stack to estimate what should be the stack size. So if you have large arrays you may use a pointer + a call to malloc instead. If this can not fix […]

July 4, 2010July 4, 2010 by Jean-Luc Aufranc (CNXSoft) - No Comments

Digital Signage Standard by POPAI

Currently digital signage implementations are mainly proprietary, and that means once you choose a vendor you are stuck with it, unless you completely change your network and the way you manage your content or handles separate systems. If the digital signage industry really wants to take off some standards are needed. One of the first standard for digital signage has been released by POPAI (Point of Purchase Advertising International). This first standard is to promote interoperability between different providers by defining Screen Media Formats (Click to open the standard) basically telling which video and audio codecs and containers (“Wrappers”) and which and picture formats should/could be supported by digital signage players and providing different levels of standard profiles and extended profiles a bit like it is done in MPEG-4 specifications. POPAI also used to provide some media samples to test your system previously available at www.popai.com/DS/ContentSamples but the link is […]

July 4, 2010 by Jean-Luc Aufranc (CNXSoft) - No Comments

Installing 2 Linux distributions in one PC

Here are the step I followed to install two distributions of Linux: Install the first distribution normally with GRUB in the MBR. While installing the second distribution make sure to set GRUB in its root partition. At this point the second distribution should not be available in GRUB Boot loader, login in the first distribution as root and edit /etc/grub.conf and add the following lines: Linux Distribution 2 root (hd0,2) chainloader +1 Save and restart your PC you should have 2 choices in GRUB, select “Linux Distribution 2”or whatever name you gave in grub.conf and this should start the second Linux distribution. Jean-Luc Aufranc (CNXSoft)Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011. www.cnx-software.com