Everything about UNIX kernels: development, configuration, compilation, design, etc.

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NTPD Nanokernel

I had a couple of questions about the NTP Nanokernel as explained here: http://www.eecis.udel.edu/~mills/database/brief/nano/nano.pdf The big question is how does this Nanokernel manage to deliver an ...
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72 views

Output shutdown messages to multiple consoles

I have configured my system to direct console output on boot to serial and vga using kernel parameters. Serial is the last argument in the kernel parameters and will be the default used for ...
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506 views

Debian driver needed for Intel ICH7M SouthBridge I/O controller

I am using a motherboard based on this architecture. http://www.intel.com/content/www/us/en/intelligent-systems/navy-pier/embedded-intel-atom-n270-with-mobile-intel-945gse-express-chipset.html I ...
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264 views

Enabling GPIO in kernel not working

I have tried to enable the GPIO pins for my system through the Kernel but I am not able to get them to work. When I try this: echo 1 > /sys/class/gpio/export The terminal window just closes. ...
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242 views

How to enable VESA framebuffer as default in NetBSD 6.1

When booting NetBSD, the old Tecra 720CDT that I have, works quite nicely in 1024x768x15 mode with vesa fb. I always have to activate VESA when booting the system: > vesa on > vesa 0x116 > ...
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149 views

Can I get WCHAN from ps on Mac OS X 10.7.4?

From the manual it seems that ps -AO wchan should tell me what everything is sleeping on, but everything comes up as -. (And nwchan as 0). Did they do away with the old sleep()/tsleep() interface in ...
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61 views

Explanation of the building process of the kernel on Ubuntu/Debian systems

I'm getting into Linux kernel programming and I have successfully built my own kernel several times now. However, I have done it using step by step guides found from the internet and I don't really ...
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60 views
+100

Why will plymouth not update?

I admit I don't update my kernel very often. I used to everytime a stable release of sys-kernel/gentoo-sources came out so I'm very adept at doing it. This last weekend I attempted to update from ...
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36 views

Why does each process folder under /proc contain the same information?

Under /proc/<PID>/net pseudo-file system each process seems to have files with the same content. For example I use cat /proc/<PID>/net/ip_tables_names to list iptables tables under the ...
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34 views

Why is there no rootfs file system present on my system?

The linux kernel documentation claims: Rootfs is a special instance of ramfs (or tmpfs, if that's enabled), which is always present in 2.6 systems. You can't unmount rootfs … On all linux ...
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111 views

kernel build: why does 'make install' complain about missing modules?

I'm building a 3.2.x kernel on a RedHat Enterpise system. During 'make install' it takes a very long time and is complaining : ERROR: modinfo: could not find module xxx I assume its probing ...
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295 views

graph TCP connection performance based on `ss -i`

A nearby question has brought to my attention the ss utility on Linux, another utility to investigate sockets. It would appear that it may be a great tool to monitor the performance of, say, an ssh ...
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184 views

How can I compile minix when I make changes in libraries

I am looking for a way to compile minix. The make hdboot command seems to do nothing with the directories under /usr/src/lib. I changed only one .c file in syslib. Do I have to do make world for this ...
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719 views

“Kernel panic - not syncing” after building Centos-6/elrepo 3.10.19 kernel from source

I need to rebuild the Centos-6 / elrepo 3.10.19 kernel from source. Background: the GVision touch screen drivers are incompatible with kernels > 3.8 and require source code patches to add code to ...
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282 views

TUN/TAP Will not load

I have an OpenVZ server but can't seem to get the tun/tap module to load. I ran modprode tun on the hostnode but when I go under the VM I get: Tue Sep 24 03:08:36 2013 Note: Cannot open TUN/TAP dev ...
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738 views

Unable to install the selected kernel

I have problem with my DVD drive. It's corrupted and when I'm trying to install Ubuntu it stucks (even with the miniISO) I was able to successfully start the OS from system rescue CD. I'd like to ...
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124 views

Is there a way to undo VGA adapter modesetting in Linux

I'm looking for a way to reset the graphics adapter to textmode after it has been set to some sort of graphical mode by the kernel on bootup, and possibly used by an X server. Is there any code to do ...
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56 views

kgdb not returning control to gdb

I've compiled a kernel with kgdb support and I'm trying to debug it. I have two machines running, a debug machine (running the kgdb kernel) and the machine I'm using to debug it. They are connected ...
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310 views

Failed to execute shell script from “network” udev rule to change the MAC-address

I am trying to execute a shell script from udev rule, when a network interface is added, as follows: SUBSYSTEM=="net", ACTION=="add", KERNEL=="eth*", PROGRAM="/usr/local/bin/changemac.sh", ...
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633 views

Kernel does not detect Hardware / Software or Hardware fault

I've got more of a basic question for you: My linux kernel (I tried several here from stock 2.6, 3.2 and 3.5 as well as a custom 3.7.3 one) does not detect my synaptics touchpad - or I'am too dumb ...
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343 views

Booting over the LAN using uboot

I am trying to boot my beaglebone over the LAN. I am able to download the Kernel uImage from the TFTP server. Here is what I did - U-Boot SPL 2011.09-00053-gb423c52 (Aug 10 2012 - 11:26:55) Texas ...
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379 views

Delayed write scenario

I was reading the design of unix OS by Maurice J bach and had a confusion. Suppose a process requests for a buffer for disk block number 18. The kernel searches for a free buffer from the free list. ...
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91 views

How to deal with closed source modules when configuring a new kernel build

I found this command very useful: make localmodconfig However, having some closed source drivers/modules ends up being a problem because this command can't find an appropriate way of including the ...
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65 views

What are the differences between the current Linux kernel and the Unix SVR4 kernel in terms of device drivers+i/o and virtual files systems?

Yes I realize that Linux supports many more file systems and recognizes more devices than Unix SVR4. I'm interested in what the differences are in the abstraction on top of an actual file system, or ...
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112 views

How to find where driver.mod.c links to?

I'm trying to port the webcam composite gadget from kernel 2.6.37 to 2.6.32. I don't have a choice on this since I depend on other drivers and a SDK which only compile for this version. My train of ...
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442 views

Can I apply real time Linux kernel patch on Android kernel?

I would like to apply real time patch on the Android kernel (given I've found Kernel patch for corresponding Kernel version). Is it possible or should I create a patch specifically for the purpose of ...
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673 views

Qemu doesn't boot kernel after “Uncompressing Linux… done, booting the kernel. ”

I've compiled qemu for s5pc110 (it's from http://gitorious.org/samsung-linux-platform/qemu, somebody had added support for s5pc110), version 0.12. But when I load the kernel: qemu-system-arm -M ...
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235 views

Perform test of aes-ni and aes module in linux kernel

Since both aes-ni and aes module are available in linux kernel , how can I give it a performance test , to decide which one's faster ?
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484 views

To what does the byte sequence in this kerneloops (syslogd@hostname) message refer?

Message from syslogd@ROOROO at Mar 22 19:36:12 ... kernel:[13988.165672] Oops: 0000 [#1] SMP Message from syslogd@ROOROO at Mar 22 19:36:12 ... kernel:[13988.169607] Stack: Message from ...
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174 views

What are the current differences between tuxonice and µswsusp?

I tried to find out what is the current comparation between TOI and µswsusp. Unfortunately I could not find any recent information about the state of hibernation in Linux and how TOI compares to ...
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233 views

Uname gives unfamiliar timestamp for kernel

I'm recompiling a new kernel (adding some debugging info) on Ubuntu by doing the following: make vmlinux; make install; after this I do a reboot and select my new custom kernel from the list. ...
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669 views

Linux kernel slab usage growing on embedded system

I'm in the process of QA/debugging a project on a custom embedded linux system. The problem we're VERY tight on memory, and even a couple megs can cause issues with our software. What I'm seeing ...
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12 views

Error compiling buildroot

i updated my buildroot for the version "2014.08" (stable version) and i updated the Kernel version (3.12.26) of my project, when the buildroot try to build the "linux-headers-3.12.26" package, occurs ...
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20 views

What exactly does struct nfs_unlinkdata do?

I been reading the source code of unlink() but i am stuck on nfs_unlinkdata and i can't find anything on it on the web. Thanks a lot for your help.
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HD 4800 lower fan speed

I've installed Linux Mint 17, most important thing for me is to lower the fan speed to 30% as I am doing in Windows because it's really too noisy. Note that the temperature stays at ~50°, so this ...
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24 views

real time kernel / low latency comes from the vanilla source

Does the vanilla source provide real time / low latency functionality ?
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15 views

ifup wlan0 causes kernel Oops

on my laptop, when I do ifup wlan0, sometimes I get following call trace in dmesg. Other times, the log looks perfectly normal, and there are no kernel Oops messages. In both cases (with errors and ...
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28 views

How to suppress input overrun messages

I have a Raspberry Pi running Raspbian (a Debian flavor: Linux version 3.12-1-rpi (debian-kernel@lists.debian.org) (gcc version 4.7.2 (Debian 4.7.2-5+rpi1) ) #1 Debian 3.12.9-1+rpi1 (2014-05-19) ). ...
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29 views

can't filter printk messages

I'm writing a driver and usually I implement my own log-level scheme. However, this time I figured that I would try to utilize the printk scheme that is built into Linux. I see that I can adjust the ...
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22 views

How/where are linux device capabilities / bitfields set?

I have a device that has this output in /proc/bus/input/devices: I: Bus=0003 Vendor=05b8 Product=3280 Version=0111 N: Name="PixArt USB Optical Mouse" P: Phys=usb-0000:00:1a.0-1.1/input0 S: ...
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69 views

iwlwifi: timeout delays firmware to be loaded

I'm using OpenSuSE 13.2 beta (which runs by the way very nicely). When starting up, my wireless adapter (Intel Centrino Ultimate-N 6300 AGN/Thinkpad T420) delays about one minute... But then it works ...
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40 views

Linux Oracle - Random crash CPU Stuck

I have several Linux oracle VMs running under hyper-V. Kernel version is 2.6.32-358.el6.x86_64. Sometimes, the VM stuck, we still can ping it, but we cannot ssh, or through the hyper-v console this ...
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31 views

How build wireless-compat-old in-kernel?

I'm running linux 2.6.24 with custom patches from Freescale, on an embedded board. I want to use a usb wlan modem that uses the Realtek rtl8191su chipset. Realtek provides a driver out of tree, ...
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23 views

extract Embedded initramfs

I have a kernel in which one initramfs is embedded. I want to extract it. I got the output x86 boot sector when I do file bzImage I have System.map file for this kernel image. Is there any way to ...
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74 views

Linux 0.0.1 Kernel - Starting Kernel Programming

To start kernel programming, instead of reading the books, the online references suggested to download the linux 0.0.1 source and find bugs. I have downloaded it and I am going through the code with ...
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Kexec immediately after Kickstart install (where is cmdline?)

I used to be able to kexec into a new kernel immediately after a kickstart (anaconda) install via pxe. I was able to do this by figuring out the current kernel version, and grabbing cmdline options ...
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“disagrees about version” message

I get a message "disagrees about version" on boot time, after compiling kernel and modules with KGDB. Why should this happen ? Is there any problem with KGDB ? This is the relevant log at boot: ...
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56 views

What does __ prefix before some kernel api's convey?

Why do some function calls in kernel specially have this prefix __ example: __init initialization(void) is __init a macro? What does this convey? Are these a special class of function calls inside ...
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27 views

CPUFreq Kernel module

I would like to try the CPUFreq module on my board (Marvell Soc based on ARMv7 running a v3.15 linux kernel). My architecture is obviously not supported by the default source code (located in the ...
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85 views

cross compile embedded arm

I have the android 4.2.2 code in directory /home/sghPhone2 which compiles normal with make menuconfig but I need to compile a 4.4 kernel and possibly patch it but when I download the source from ...