klogg says

2011-12-19T23:24:00.001+02:00

KS2011: Patch review (by LWN.net)

2011-10-26T03:08:00.003+03:00

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

2011-10-22T00:08:00.000+03:00

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)

2011-06-24T08:47:00.008+03:00

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/android-2.6.35
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

2009-11-29T19:29:00.001+02:00

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

2009-03-07T18:44:00.004+02:00

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 :)

wireless performance

2008-12-07T00:27:00.005+02:00

QNX has adopted 802.11 wireless stack (as a part of the whole networking stack) from the NetBSD sources. Since 802.11n is not yet supported by the NetBSD so it is worth to implement support. It would be interesting to measure its performance and compare with the Linux wireless stack. Of course, the OSes are totally different but still from the POV of a RG or video bridge it would be interesting to compare the performance in terms of maximum throughput and pps.
So I need to:

choose a HW platform for the tests (I guess PXA dongle with 32MB of RAM should be OK)
make a QNX 6.4 BSP for it using already existing BSPs
make a Linux BSP for it using preferably E-CLFS with some latest kernel
compare performance in general (ethernet routing/bridging)
make a clean ethernet-like MTLK Linux driver
make a clean ethernet-like MTLK QNX driver
compare performance again

Note, no native wireless stack usage at this point. We'll see how QNX will progress with that :)