Sparse is dead?

Just noticed that Linux kenel sparse tool is not maintained well anymore. It has two repositories actually:

• on kernel.org http://git.kernel.org/?p=devel/sparse/sparse.git
• and on github.com https://github.com/chrisforbes/sparse

but unfortunately both are not seem to be supported anymore. In order to make my small program work with cgcc I had to apply few patches fixing GCC incompatibilities, but reviewing sparse code further I see lots of other issues; there are lots of fixing patches hanging in the internet, too. It's pity but this nice tool seem to be dead.

Update: sparse cannot even handle arrays of boolean, what a shame...

Conky GUI on xUbuntu 12.04 and Oracle JDK 1.7

Recently I have found a nice tool to replace Gnome Screenlets on my XFCE desktop and provide all sorts of technical details - memory usage, CPU usage, IO load, network stats, etc. - Conky. It is highly flexible and provides a Lua interface and also whatever you can imagine for this kind of tool. More info on the project page or on the Wikipedia; you can find there good examples of config files, different tweaks and additional software.

Unfortunately, there is no GUI to write conky configuration scripts except Conky GUI which does not seem to be maintained anymore. Last thing was done in May 2012 when project has been moved to Github. The .deb package from the website didn't worked for me so I have decided to build my own version. It turned out that some minor fixes were needed to run it with Oracle JDK 1.7 and new JUnit, patches can be found here.

UPDATE: Amazing samples of Conky configuration!

Eclipse + kernel

Indexing in Eclipse is finally working correctly.
http://wiki.eclipse.org/HowTo_use_the_CDT_to_navigate_Linux_kernel_source

socat

While playing with Android libsensors virtual HW access I have decided not to torture my PandaBoard with soldering additional serial port (note it has only one with console connected to it by default) and use some sort of a virtual serial port instead connected to real HW over the network:

After googling a while I have found a nice tool 'socat' that allows to... well, it can do almost everything, checkout on the project website: http://www.dest-unreach.org/socat/

It only turned out that Android build script has a minor bug in it I had to fix (see below 'android_termios_shift_fix.patch') and also there is a problem with PTYs support. By default openpty() and other related functions are absent in Bionic library, while Linux kernel configuration used in Android implements UNIX98 PTYs. In order to get my small system working I have ported openpty() function from uClibc which seemed to be quite enough for socat to get it working. The 'enable_android_pty.patch' adds an 'openpty.c' file to the build and modifies Android build script to perform following changes when it is invoked:
 - enable HAVE_OPENPTY and HAVE_GRANTPT features in config.h
 - add openpty.c to the Makefile
Actually this is a quick-n-dirty solution: it produces a warning for openpty() since no pty.h header exist, the port itself is a license violation, etc., but I don't really care at the moment - the whole 'socat_buildscript_for_android.sh' distributed with socat is a dirty hack.

So I've got everything working and I can also capture and analyze packets going trough serial port with Wireshark by just writing a simple dissector! sweeeeet...

Patches are available here.

Socat is used on host (sandbox) with following command:
socat tcp-l:54321,reuseaddr,fork /dev/ttyS0,raw,b115200,echo=0
and on panda with:
socat pty,link=/dev/ttyS0,raw,echo=0 tcp:sandbox:54321

KS2011: Patch review (by LWN.net)

I have read an interesting article by Jonathan Corbet on the "patch review" session on 2011 Kernel Summit. Needless to say, patch review process in both open-source and proprietary projects is a very interesting and challenging topic, especially when it goes to a big software systems with thousands people working on them. While reading the article I have found a point not really relevant to the review process, but very interesting from the prioritization POV

As one might imagine, the discussion became rather unfocused and fragmented for a while. It came back together when Linus took the microphone and stated that, simply, code that actually is used is the code that is actually worth something. The Android code is certainly being used; the in-kernel code aimed at the same problems is just a vague idea that is worthless in comparison. We should, he said, consider merging suspend blockers as a real option. Even if it truly is crap, we've had crap in the kernel before. The code does not get any better out of tree. Alan Cox agreed that it is probably a good idea to merge that code. The interface is important and has a lot of users; getting the code merged is the best way to fix the implementation. Ingo also agreed, saying that when code has millions of users, we have to say "yes" to it. 

This is a really interesting statement, I do fully support it. It does not neglect the need to improve code quality with time - it only sets priority. It is really weird that so many people (including really good software engineers) do not understand this...

Ubuntu 11.10 sucks

Recently I have switched to Ubuntu 11.10 as a primary OS on my Dell D630 laptop. Of course, I have disabled the Unity... and surprisingly found that Gnome 3 new UI (which I have not tried before) is taking same direction as Unity. Moreover, most of system settings disappeared, default Alt-Tab switching does not work without special tweaking, no status bar. Oh, almost forgot - they are not going to continue using Compiz anymore. So the system is basically not usable without good hacking and fine tuning... It is pity, what happened with Ubuntu, I think I will switch to a different distribution or roll back to some previous version. Too bad.

kernel development using Eclipse (OMAP4 pandaboard + 2.6.35 + Android)

Working with kernel sources

Just found out that guys in my team are using all different editors for kernel code debugging - and all not very effective enough... Of course the best solution IMHO is till gvim + ctags, but if you wish something more fancy :) you can go with Eclipse - so I've tried to set it up on my fresh Ubuntu 11.04 x64

1. Download and install toolchain
For the reasons unknown I have decided to use Linaro toolchain for my games. According to Linaro HOWTO this is as simple as entering one command for natty:
  sudo apt-get install gcc-arm-linux-gnueabi
of course, I have all my Ubuntu build tools preinstalled.


2. Download the kernel sources
Since I am going to use OMAP4 pandaboard with 2.6.35 kernel on Android - I am following instructions on OMAPpedia wiki to pull the kernel:

  git clone git://git.omapzoom.org/kernel/omap.git kernel
  git checkout -b p-android-omap-2.6.35_local remotes/origin/p-android-omap-2.6.35

Before building the kernel with latest Linaro toolchain I need to apply a patch that resolves binutils architecture issues with 2.6.35 kernel.


diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
index 884eb1f..6854066 100644
--- a/arch/arm/mach-omap2/Makefile
+++ b/arch/arm/mach-omap2/Makefile
@@ -30,8 +30,10 @@ obj-$(CONFIG_HOTPLUG_CPU) += omap-hotplug.o
  obj-$(CONFIG_ARCH_OMAP4) += omap44xx-smc.o omap4-common.o \
                              omap4-wakeupgen.o

-AFLAGS_omap44xx-smc.o :=-Wa,-march=armv7-a
-
+plus_sec := $(call as-instr,.arch_extension sec,+sec)
+AFLAGS_omap-headsmp.o :=-Wa,-march=armv7-a$(plus_sec)
+AFLAGS_omap44xx-smc.o :=-Wa,-march=armv7-a$(plus_sec)
+
 # Functions loaded to SRAM
 obj-$(CONFIG_ARCH_OMAP2420) += sram242x.o
 obj-$(CONFIG_ARCH_OMAP2430) += sram243x.o
@@ -69,6 +71,7 @@ obj-$(CONFIG_OMAP_SMARTREFLEX_CLASS1P5) += smartreflex-class1p5.o

 AFLAGS_sleep24xx.o :=-Wa,-march=armv6
 AFLAGS_sleep34xx.o :=-Wa,-march=armv7-a
+AFLAGS_sleep44xx.o :=-Wa,-march=armv7-a$(plus_sec)

 ifeq ($(CONFIG_PM_VERBOSE),y)
 CFLAGS_pm_bus.o += -DDEBUG
diff --git a/security/smc/omap4/Makefile b/security/smc/omap4/Makefile
index af345a1..af545a2 100644
--- a/security/smc/omap4/Makefile
+++ b/security/smc/omap4/Makefile
@@ -38,4 +38,7 @@ tf_driver-objs += tf_comm_mshield.o
 tf_driver-objs += tf_device_mshield.o
 tf_driver-objs += bridge_pub2sec.o

+plus_sec := $(call as-instr,.arch_extension sec,+sec)
+AFLAGS_bridge_pub2sec.o :=-Wa,-march=armv7-a$(plus_sec)
+
 obj-$(CONFIG_SECURITY_MIDDLEWARE_COMPONENT) += tf_driver.o

This was already fixed on the latest kernels, refer to this thread for details. If you are using CodeSourcery toolchain referred in OMAPpedia wiki - you don't need it.
Compile the kernel with pandaboard defconfig (as per latest available L27.12.1-P2 release notes) with modified toolchain


  make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- distclean
  make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- android_4430_defconfig
  make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- uImage

Later we will need to follow full instructions - patches, folders, environment variables, but to start working with kernel this should be pretty enough.

3. Download and install Eclipse
I prefer not to use one that is supplied with Ubuntu so I am just downloading Eclipse IDE for C/C++ Linux Developers 64-bit  from eclipse.org. Prefer to keep it in the opt folder usually...

  cd /opt
  sudo mkdir eclipse
  sudo chmod a+rwx eclipse
  tar -xvzf ~/Downloads/eclipse-linuxtools-indigo-incubation-linux-gtk-x86_64.tar.gz 

There is an ugly bug in the latest eclipse when it crashes during index rebuilding so I had to use a workaround offered by Marc-Andre Laperle with adding
  -XX:-UseCompressedOops
to eclipse.ini file. Probably I will also need to increase the maximum memory usage limitations later.

4. Configuring Eclipse to work with Linux kernel
Some time ago I used to use one python script to generate kernel symbols for the .project file, but today I have found a very nice article on how to correctly index kernel with Eclipse on the eclipse.org wiki. My customizations:

• Step 14: since we are doing cross compilation, I need to add custom build variables in the corresponding menu of the C/C++ Build options. Add ARCH with value arm and CROSS_COMPILE with value arm-linux-gnueabi- to all configurations. Maybe I will need to add some compiler options later here, but for now it is quite enough
• Step 15: use arm-linux-gnueabi-gcc for compiler command
• Step 25: here I have arch/arm/include, also I had to add arch/arm/plat-omap/include and arch/arm/mach-omap2/include
• Step 33: here I have everything except arch/arm
• Additionally in C/C++ Build options I am setting Build target in the Behavior tab to uImage and Build command in the Builder Settings tab to make ARCH=${ARCH} CROSS_COMPILE=${CROSS_COMPILE}
• In the end you will need to clean and rebuild from Eclipse to get the list of issues 

Your Eclipse is ready to work with OMAP4 2.6.35 Android kernel code. Enjoy...

802.11s Mesh Networking

FreeBSD 8.0 recently announced has updated 802.11s Mesh Networking implementation to D3.03. Still not clear if it can interoperate with Linux's implementation. Anyone tested it?

Public support for Metalink added

Assembla space for MTLK OpenWRT support can be found here. I'd like to create a simple and easy-to-configure web interface for Kiev MTLK developers and testers, current implementation seem to me quite ugly and lacks of different nice features. I'll try to build an RG for myself using it :)