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May 16, 2016May 29, 2017 by Jean-Luc Aufranc (CNXSoft) - 2 Comments

Linux 4.6 Release – Main Changes, ARM and MIPS Architectures

Linus Torvalds released Linux Kernel 4.6 earlier today: It’s just as well I didn’t cut the rc cycle short, since the last week ended up getting a few more fixes than expected, but nothing in there feels all that odd or out of line. So 4.6 is out there at the normal schedule, and that obviously also means that I’ll start doing merge window pull requests for 4.7 starting tomorrow. Since rc7, there’s been small noise all over, with driver fixes being the bulk of it, but there is minor noise all over (perf tooling, networking, filesystems, documentation, some small arch fixes..) The appended shortlog will give you a feel for what’s been going on during the last week. The 4.6 kernel on the whole was a fairly big release – more commits than we’ve had in a while. But it all felt fairly calm despite that. Linux 4.5 added […]

March 4, 2016May 29, 2017 by Jean-Luc Aufranc (CNXSoft) - 2 Comments

Embedded Linux Conference 2016 and OpenIoT Summit 2016 Schedule

The Embedded Linux Conference 2016 and the OpenIoT summit 2016 will take place on April 4 – 6, 2016 in San Diego, California, and over 800 attended will meet including kernel & system developers, userspace developers, and product vendors. The Linux Foundation has recently published the schedule, so I’ve had a look at some of the talks, and designed my own virtual schedule to find out more the current development focus although I won’t attend. Monday April 4 10:40am – 11:30am – Linux Connectivity for IoT by Marcel Holtmann, Intel OTC There are many connectivity solutions that available for IoT. For example Bluetooth Low Energy, 802.15.4, Zigbee, OIC, Thread and others. This presentation will provide and overview of the existing technology and upcoming standard and how they tie into the Linux kernel and its ecosystem. 11:40 – 12:30 – BoF: kernelci.org: A Million Kernel Boots and Counting by Kevin Hilman, […]

December 7, 2015December 7, 2015 by Jean-Luc Aufranc (CNXSoft) - 2 Comments

How to extract kernel.img with mkboot script

As I tried instructions to install Linux on Amlogic S905 Android TV boxes yesterday, I wanted to extract kernel.img file found in Android firmware, but Google did not help that much until I found mkboot part of mkbootimg_tools scripts. But first let’s see how kernel.img is created… Google provide a Python script called mkbootimg that combine the kernel image (e,.g. zImage), a rootfs/ramdisk and the device tree (DTB) file with a command line that looks like:

./mkbootimg --base=0 --kernel_offset=0x01080000  --kernel ${KERNEL} --ramdisk_offset=0x01000000 --ramdisk ./${ROOTFS} --second ${DTBFILE} --output ./kernel.img

1	./mkbootimg --base=0 --kernel_offset=0x01080000 --kernel ${KERNEL} --ramdisk_offset=0x01000000 --ramdisk ./${ROOTFS} --second ${DTBFILE} --output ./kernel.img

However, AFAIK the company does not provide a “unmkbootimg” script, and mkbootimg can only be used to create kernel.img, not decompile it. But that’s what mkboot does, and it works for kernel.img and recovery.img. Let’s retrieve the necessary files first:

git clone https://github.com/xiaolu/mkbootimg_tools

1	git clone https://github.com/xiaolu/mkbootimg_tools

mkboot is a bash script so we can use it right away:

cd mkbootimg_tools
./mkboot 
<Unpack and repack boot.img tool>
----------------------------------------------------------------------
Not enough parameters or parameter error!
unpack boot.img & decompress ramdisk：
&nbsp;&nbsp;&nbsp; mkboot [img] [output dir]
&nbsp;&nbsp;&nbsp; mkboot boot.img boot20130905
Use the unpacked directory repack boot.img(img_info)：
&nbsp;&nbsp;&nbsp; mkboot [unpacked dir] [newbootfile]
&nbsp;&nbsp;&nbsp; mkboot boot20130905 newboot.img

cd mkbootimg_tools

./mkboot

----------------------------------------------------------------------

Not enough parameters or parameter error!

unpack boot.img & decompress ramdisk：

    mkboot [img] [output dir]

    mkboot boot.img boot20130905

Use the unpacked directory repack boot.img(img_info)：

    mkboot [unpacked dir] [newbootfile]

    mkboot boot20130905 newboot.img

So it can be used both for unpacking and repacking kernel.img to/from the output directory. Let’s run the command […]

December 6, 2015December 6, 2015 by Jean-Luc Aufranc (CNXSoft) - 118 Comments

How to Run Headless Linux on Amlogic S905 Devices Such as MINI MX or K1 Plus

A few week ago, I had been informed that Amlogic S905 U-boot and Linux source code was released, and one person use the code and other resources to load a minimal Ubuntu 14.04 image to his K1 Plus TV box and released the installation instructions and the image (Thanks olin!). I also have K1 Plus here, but since I’ve just finished reviewing Beelink MINI MX, I decided to use the latter instead. The instructions below boot Linux from the (micro) SD card, and can still boot Android if you remove the SD card. Modifying U-boot environment The instructions include opening the box, and connecting or soldering a USB to TTL debug board to access U-boot and change some parameters. But later once an image with network is working, you could also build and load fw_setenv and fw_saveenv, and do the same steps with an Android shell and without the need […]

September 2, 2015May 29, 2017 by Jean-Luc Aufranc (CNXSoft) - 1 Comment

Linux 4.2 Release – Main Changes, ARM and MIPS Architectures

Linus Torvalds released Linux Kernel 4.2 last Sunday: So judging by how little happened this week, it wouldn’t have been a mistake to release 4.2 last week after all, but hey, there’s certainly a few fixes here, and it’s not like delaying 4.2 for a week should have caused any problems either. So here it is, and the merge window for 4.3 is now open. I already have a few pending early pull requests, but as usual I’ll start processing them tomorrow and give the release some time to actually sit. The shortlog from rc8 is tiny, and appended. The patch is pretty tiny too. Go get it, Linus Some notable changes made to Linux 4.2 include: File systems New features for F2FS including per file encryption CIFS support SMB 3.1.1 (experimental) Cryptography – Jitter Entropy Random Number Generator, Chacha20 stream cipher and Poly1305 authentication (RFC7539),New RSA implementation. See lwn.net […]

August 28, 2014August 29, 2014 by Jean-Luc Aufranc (CNXSoft) - 10 Comments

Samsung Exynos 7 ARM Cortex A57 Processor Linux Code Submitted

Samsung has not announced any 64-bit processor yet, but according to a recent patchset Exynos 7 may be their first 64-bit ARM SoC, and it will be based on the faster Cortex A57 cores. A quick way to learn a little more is to check the device tree file (exynos7.dtsi). Here’s an interesting snippet:

+	cpus {
+		#address-cells = ;
+		#size-cells = ;
+
+		cpu@0 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a57", "arm,armv8";
+			reg = ;
+		};
+	};

+ cpus {

+ #address-cells = ;

+ #size-cells = ;

+ cpu@0 {

+ device_type = "cpu";

+ compatible = "arm,cortex-a57", "arm,armv8";

+ reg = ;

+ };

As it stands, Exynos7 would be a single core Cortex A57 processor. This sounds unlikely that a company would launch a single core processor at this stage, so it’s probably early code that may not support all cores just yet. We also know Samsung uses ESPRESSO board for development with Samsung Exynos 7 processor and 3 GB RAM. Thanks to David for the tips. 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 […]

August 21, 2014May 29, 2017 by Jean-Luc Aufranc (CNXSoft) - 2 Comments

Embedded Linux Conference Europe 2014 Schedule – IoT, ARM vs x86, Optimization, Power Management, Debugging…

The Embedded Linux Conference Europe (ELC 2014), CloudOpen, and LinuxCon Europe will jointly take place at the Congress Centre Düsseldorf, in Germany on October 13 – 15, 2014. The 3-day events will consists of keynotes, presentations, and tutorials. Each day will open with two or three keynotes by speakers including Jim Zemlin (Executive Director, Linux Foundation), and Jono Bacon (XPRIZE), followed by presentation and tutorials. There will be 45 presentations for ELCE, 58 for LinuxCon, and 47 for CloudOpen, I’ll make a virtual schedule with a few sessions part of the Embedded Linux Conference Europe “track”. Monday, October 13 11:15 – 12:05 – Performance Analysis Using the Perf Suite by Mans Rullgar, Consultant When faced with a performance problem, the initial steps towards a solution include identifying the sections of code responsible and the precise reasons they are time-consuming. To this end, the ‘perf’ profiling tools provide valuable insight into the […]

May 12, 2014May 12, 2014 by Jean-Luc Aufranc (CNXSoft) - 57 Comments

How to Extract a Device Tree File from Android Firmware Files

Up to now, all our cheap Android devices were based on older Linux kernel (3.0.x, 3.4.x) that still used board files (arch/arm/board, but we’ve recently seen companies like Amlogic and Rockchip release source code with Linux kernel 3.10.x. One of the key differences between these version are the move from board files to flattened device tree and multi-platform support. If it is fully implemented, a single kernel image should be able to boot multiple hardware platforms, and all low level configuration handled by the device tree file. Since I’ve connected the serial port of Tronsmart Vega S89 for debugging, and it’s a slow news day, I thought I might try to boot the Linux kernel I compiled myself, but one of the challenge was to get the device tree file. I’ll show how to extract it from the firmware. It should also be possible to get it directly from the […]