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

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Why kernel modesetting, instead of privilege separation?

Kernel modesetting was kind of painful to get on Linux at first, but now it's pretty awesome to have. I mean, X not need to run as root? High-res hardware accelerated consoles? Cool stuff. Problem ...
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284 views

Connection problem with usb3 external storage on linux (UAS driver problem)

On Ubuntu 15.10, when i want to format into NTFS file format an external 4TO disk connected by USB3 (on a Starteck USB/ESata HDD dock), i have a lot of I/O Error, and format fail... I try GParted v ...
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403 views

Centos 7 boot up with custom kernel problem

I have installed centos 7 on virtualbox machine which has kernel-3.10.0-123.20.1.el7.x86_64. I am trying to build Linux kernel from kernel sources. I downloaded the kernel source files from: ...
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894 views

update kernel without restart

Recently Linux got a new feature called Live Kernel Patching, which you means you dont have to restart your system to update kernel. Is there any other kernel which has this feature already or Linux ...
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35 views

Automated kernel recompilation on security patches?

I'm on Ubuntu 14.04 and really enjoy the fact that I get automatic kernel security updates. When a kernel security problem is patched, a new package will be shipped with the new version. My machine is ...
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86 views

Boot rescue kernel at high memory address using kexec on arm

Summary: Crashkernel boots at 512MB address in RAM with kexec -e/-l but not with kexec -p - why? Embedded platform with Marvell Armada XP (MV78460) (ARMv7 with 4 cores) and 1GB of RAM. production ...
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25 views

What's the Debian way to retain a kernel config change through updates?

I have an embedded system running Debian. It is supposed to auto-update in order to pull in security fixes. But Debian's default kernel lacks a hardware driver that this system needs, so it will need ...
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94 views

ABRT report says “irq 19: nobody cared”, but why?

Every couple weeks, I need to reboot my system. When I do, and enter as root in the terminal, the following message (in some variation) appears: ABRT has detected 3 problem(s). For more info run: ...
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40 views

What could cause dropping cache to be extremely slow on a large cluster?

I'm attempting to time file I/O on my disks. In order to make sure all the I/O is happening off the hard drives and not from ram, before I time any read, I run a drop cache command. Specifically, I ...
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350 views

How to prevent kernel or any broadcast messages from flooding the TTYs?

Because of some hot-plugging issue, similar to what talked of here, the TTY displays show a continuous stream of messages (which are also logged in the /var/log directory). Every text I key in flows ...
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59 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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386 views

Some questions compiling linux kernel with make-kpkg

I'm doing my first steps compiling the linux kernel and adding a new system call. I've managed to do it, but I still have some questions. For this task, I has set up a Virtual Machine guesting debian ...
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579 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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198 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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2k views

SCTP support for Linux kernel 3.3.4-5.fc17.x86_64

I'm using Fedora 17 64-bit version, with Linux kernel version 3.3.4-5.fc17.x86_64. I installed lksctp using yum. sudo yum install lksctp-tools.x86_64 When I try to run sctp_status -H 127.0.0.1 ...
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7 views

FIPS mode, signature verification failed

I am building a kernel with FIPS mode on. I followed most of the procedures described on Red Hat documentation here. I also created a hmac signed .vmlinuz file. After installing dracut-fips and ...
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32 views

Kdump.service FAILED centOS 7

I am getting this error on my centos 7 x86_64 after "yum update". After rebooting the host it went into emergency mode. after entering this: systemctl status kdump.service I get this: ...
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470 views

Xorg on skylake graphics hangs

I've bought msi gs40 that has intel i7 6700HQ which means integrated graphics hd 530. After a day of struggling I was able to start xorg with HD530. For this I addes i915 to initramfs and ...
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21 views

Assign virtual core number to specific real core

Is there any way to assign ''linux core numbers'' to specific real cores? I'm working with an asymmetric architecture, so not all cores are the same, and I want to assign specific cores number to ...
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32 views

Are multiple signals given to a process served sequentially or their signal handler can cascade?

I was developing my own signal handling mechanism in User space. when browsing the kernel code and executing some c-code. I realized, Scenario 1 : When my code is executing a signal handler on ...
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34 views

Finding the Process which resulted in Kernel Panic

I have setup my linux system to generate Kernel Core Dump using KDump and kexec packages. I am using the crash tool to analyze the core dump. How do I find the call stack of the process which ...
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37 views

Compiling FreeBSD on OSX

I currently have the source for the FreeBSD kernel. I want to compile it and create an iso image, on my OSX 10.9 computer. Can this be done? Do I need any other tools?
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28 views

What is “state-object” in cgroups

I am gathering some idea about lxc, kernel name spaces and cgroups. While reading man lxc-cgroup, i find : lxc-cgroup gets or sets the value of a state-object (e.g., 'cpuset.cpus') in the ...
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50 views

Signing a module for prebuilt kernel

I am developing linux driver for my own PCI device. I have stucked up on starting my module: [14941.205599] mymod321: module verification failed: signature and/or required key missing - tainting ...
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39 views

File permissions for kernel have changed in OSX Yosmite, why?

I am working my way through the book Learning Unix for OSX Mountain Lion (I don't have access to the updated version for OSX), in which it demonstrates that using $ ls -l /mach_kernel should ...
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29 views

Significance of Linux kernel's default_console_loglevel

What is the significance of default_console_loglevel in Linux? Commonly I see it described as the default value of console_loglevel. However, what that means I haven't seen explained anywhere. ...
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181 views

How to explain strange kernel messages?

I have a server running on Debian Wheezy 3.2.68-1+deb7u1 x86_64. Lately strange records in /var/log/messages appeared. First messages of this log starts just after server reboot. 6.222.18 LEN=44 ...
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142 views

Limit system processes using cgroups

My server runs several dozens of processes that are not in my control (mostly monitoring software). According to my application logs, sometimes some of the third party processes try to allocate too ...
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334 views

is THP good or bad for MySQL Server?

Linux kernel new feature called Transparent Huge Pages (THP) which is by default enabled on CentOS 6.x and above OS. Is THP good for MySQL DB machine? I am trying following to disabled THP but seems ...
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52 views

Improve kernel boot time

I am using OMAPL138 and kernel version 2.6.37 and I would like to improve the boot time. By analyzing the kernel boot process I think it is taking a long time at MII PHY CONFIGURATION. The printscreen ...
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2k views

Install rtl8188etv/rtl8188eu driver on Orange-Pi

I'm trying to install the wifi driver on Orange-Pi board. The real chip is rtl8188etv but the driver is the same. I have compiled 3.4.105+ Kernel to have the headers: mkdir ...
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105 views

View syscalls/kernel activity for I/O from a running process

I'd like to be able to view syscalls or kernel activity for a process...I'm not actually sure of the terminology I need here! Specifically I'm looking for the difference between I/O going to local ...
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338 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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206 views

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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62 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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162 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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204 views

Debugging a “brutal” system hang (no longer responds to Alt+SysRq+B)

I've had a series of system hangs where I hoped to get a crash dump to at least get some clues but the normal "magic sysrq" functionality is broken too; not even the immediate reboot key works. The ...
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336 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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1k 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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1k views

*ERROR* timed out waiting for panel to power on

I'm using Ubuntu 13.04 on Asus VX6 (1.8GHz Atom - 2 cores, optimus nVidia ION) with Kernel 3.9.0. When I start my system I get this error: [ 15.728106] [drm:intel_enable_lvds] *ERROR* timed out ...
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1k 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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157 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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63 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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444 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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570 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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575 views

Delayed write scenario

I was reading "The Design of the UNIX Operating System" 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 ...
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111 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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89 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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207 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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651 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 ...