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

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Mouse button stops working intermittently

I have noticed that I'm not the only one with mouse button problems. This problem seems to affect multiple users on many different Linux versions regardless of Desktop versions (at least in Unity &...
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How to trace the life cycle of kernel threads by following creation and switching?

How to trace the life cycle of kernel threads by following creation and switching ? kernel_thread() and schedule() are the 2 functions I know that but have no idea how to implement it..
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268 views

Why can't I find kernel headers on CentOS 7 when trying to install VirtualBox Guest Additions?

I have a minimal CentOS 7 installation as a VirtualBox 5.0.16 r105871 guest on a Windows 8.1 host. uname -r reports "3.10.0-327.10.1.el7.x86_64". When I try to run VBoxLinuxAdditions.run I get an ...
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11 views

Difference between symlimk and link? [duplicate]

What is the difference between a "symlink" and a "link".
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64 views

What step am I missing to get my 2.6 ARM kernel running in QEMU?

I am trying to cross-compile and boot a Linux 2.6 kernel for ARM using QEMU. I have basically followed the same instructions that are included in seemingly every single tutorial on the topic. ...
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Raspbian Kernel Oops at fs/dcache.c

We have a Raspberry Pi 2 running Raspbian 8 Jessie. We are running a simple Python 3 based Flask server to read from GPIO pins and toggle a relay (Externally powered). This system is polled every ...
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18 views

Ubuntu upgrades blocked due to insufficient disk space for linux-image [duplicate]

I am running Ubuntu Server 14.04 LTS on a desktop at my home that I was intending to turn into a server, but I never really did much on it. I then decided to turn it into a send-only SMPT server, but ...
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24 views

GMA500 video chip uses mode that monitor can't sync to (even text mode)

I have a new CentOS7 installation which starts fine (I see the Grub2 menu). If I disable RHGB I can even watch bootup to a point - then all video disappears. The OS is booting to runlevel 1 (text ...
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130 views

Why can't I run android apps on generic linux? [closed]

I know about projects like archon, and various emulators exist, but it seems strange that I can run windows programs but not android programs under a stock linux kernel.
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94 views

How to get the absolute position (x, y coordinates) of a finger on a touchpad?

Main question: How to get the absolute finger position on the touchpad? I would like to get the absolute position (x, y coordinates) of a finger on a touchpad? I believe it is possible to extract it ...
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30 views

Dynamic mdev ifup and ifdown of network interface

Is it possible to have an mdev.conf rule that would run ifup on device creation and ifdown on detach? i.e. eth[0-9] root:root 660 @ifup $MDEV | $ifdown $MDEV
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183 views

How to install kernel 4.4 on debian testing?

Hello can someone tell me how to install kernel 4.4 on current debian testing ? I have a bug that might be solved by the kernel 4.4 so I want to give it a shot but can't find the name of the package ...
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How to interpret perf -e cache-misses:pp?

I find the behavior of perf top -e cache-misses:pp -p <my_pid> quite confusing. I own an Intel i5-3230M, running kernel 4.4.5 64 bit. If I just run that commmand, I get basically no samples ...
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2answers
47 views

How can I activate extra-verbose mode (debugging mode) during Debian boot?

How do I activate extra verbosity during boot, on Debian? I removed the quiet parameter and tried to add debug but it didn't help. My problem is that my keyboard takes 2-3 min to activate so it ...
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50 views

Kernel panic dump analisys

We got a kernel panic today and I think that one scsi device caused it. Can you help me to interpret this output? What does <<EOE>> mean? <0>Kernel panic - not syncing: Watchdog ...
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37 views

Build custom EDID with several modelines

I would like to build custom EDID using kernel sources. But I need to use several modelines - more refresh rates for same resolution. Is it possible using method in kernel sources? Could you please ...
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1answer
36 views

How to map Linux hard drive identifiers like “sd 3:0:0:0:” to ones like “ata8:”? [duplicate]

In my kernel log, I can see entries like: [ 0.765510] sd 3:0:0:0: [sdb] 3907029168 512-byte logical blocks: (2.00 TB/1.81 TiB) and when something fails, it's usually something like: [ ...
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1answer
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Add symbols of LKM to kernel

I am trying to get my android kernel working but I have a kernel module that is needed in order to get access to the file system of the device. Unfortunately there is no source code available so there ...
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2answers
153 views

How to make a minimal bootable linux (only with terminal) from kernel source code? [duplicate]

I want to make a very minimal linux os which only have a terminal interface and basic commands/applications (busybox is my choice for commands/apps). I don't want the installation option on my os. I ...
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2answers
53 views

What 4.2 Kernel Optimizations could I make to speed up CR48 netbook?

I have a CR48, had one for years. Love the little grimlin, but it is still a single core machine with the chances of upgrading the processor being slim and none (Even then what looks to be the best ...
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80 views

Error installing kernel from source!

I compiled the latest Linux Kernel (4.5.x) from Linus's git tree. The Kernel compiled perfectly with no errors. After compiling the kernel I installed the modules using sudo make modules_install. That ...
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1answer
66 views

How to spoof uname -rs per process

My ubuntu server returns Linux 3.13.0-63-generic when I run uname -rs. From what I found in internet, uname is also a system call which can't be easily overridden when third party program run this ...
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117 views

How to Downgrade CentOS 7.2 to 7.1 on Linode?

I can change Kernel on Linode Manager page, but I don't know how to Downgrade CentOS 7.2 to 7.1
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ip_local_port_range kernel parameter confusion

On my system we have following setting: [root@voip ~]# cat /proc/sys/net/ipv4/ip_local_port_range 32768 61000 We have asterisk running on it which is using RTP port range 12000-13000 in case we ...
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1answer
46 views

Wacom Tablet (integrated; X201T) disconnects sporadically

I have an X201 tablet with stylus and finger multitouch running Ubuntu 14.04.4 with the 4.2.0 kernel. For no apparent reason, it seems to have an affinity for not recognizing finger (henceforth ...
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3answers
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Updating kernel but not packages

I need to update the kernel from version 2.6.30 to 2.6.37. I'm going to just compile the kernel and kernel modules for this architecture and boot it. But also there are a lot of packages installed, ...
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1answer
57 views

What part of TTY subsystem control the active /dev/ttyN (TTY device driver N)? [closed]

TTY subsystem contains TTY driver, line discipline and hardware drivers (keyboard driver, display driver). Let's say I use a virtual terminal/console. So, my current session uses /dev/tty1 (TTY driver ...
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25 views

bash's pseudo terminal master [duplicate]

I learn when we use pts, there is master of pts. Then, when we type the characters on the pts(which is the terminal of bash), not only the output of bash goes to pts but also its master? I confirm ...
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1answer
44 views

Cannot compile a linux kernel for an ARM board [closed]

I am trying to compile a linux kernel (2.6.32.70) for an ARM board (versatilepb), it is my first steps in embedded linux. At the end of the compilation, two compressed kernel images are generated ...
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4answers
1k views

What exactly happens when I execute a file in my shell?

So, I thought I had a good understanding of this, but just ran a test (in response to a conversation where I disagreed with someone) and found that my understanding is flawed... In as much detail as ...
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Help debugging a kernel oops

My system has been freezing up for a while, and I keep seeing this particular kernel oops: syslog. Xorg.log Here's another similar crash from a few months ago. syslog Can you help me debug this? How ...
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Loop device support on self compiled kernel doesn't work

I compiled 3.10 kernel, I checked that these configuration lines are not commented CONFIG_BLK_DEV_LOOP=y CONFIG_BLK_DEV_LOOP_MIN_COUNT=8 When i'm trying to mount loop device I get this error # ...
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60 views

Kconfig (bool/def_bool/tristate)

In a Kconfig file, what are the differences between : bool def_bool tristate Thank you.
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28 views

perl script stall nanosleep() call in strace output

I have perl base SIP client which calling for SIP REGISTRATION process but i am seeing it stall for 10 second at nanosleep() call send(4, "REGISTER sip:sip.example.com S"..., 513, 0) = 513 select(8, ...
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CPU: 13 PID: 15452 Comm: ssd_blk/0 Tainted: G B I E 3.19.0+ #1

I developed a module which works as an emulator for a block device. When I write into the block device, I get this in dmesg and the module crashes. I cannot get any hint about what is going on? [...
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1answer
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How do I know which File Systems my linux supports? [duplicate]

I am working with linux 3.19.0+ and I want to know if my linux kernel supports f2fs (Flash-Friendly File System). How do I know that?
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How to switch static drivers like switching kernel module drivers?

I have a linux embedded device that I need to switch between USB file storage gadget driver and USB Ethernet gadget driver at runtime. The approach I use now is to build both drivers into kernel ...
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2answers
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How can strace monitor itself?

I have a Hypothetical Situation. (1) Let us say we have two strace Processes S1 & S2, which are simply monitoring each other. How can this be possible ? Well, in the command-line options for ...
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What is the role of these RPM packages( kernel-debuginfo and kernel-debuginfo-common RPMs, and the kernel-devel RPM)?

I want to know what the role of these RPM packages( kernel-debuginfo and kernel-debuginfo-common RPMs, and the kernel-devel RPM)?
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1answer
95 views

Unable to boot a kvm guest via qemu/kvm-tools

I am using ARM Foundation Model to emulate a arm-v8 environment(I need both TrustZone and KVM), and I run a kvm-enabled linux on it as the Host OS, the kernel version is 3.14.0(I clone it following ...
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1answer
95 views

Desktop completely freezing on I/O operations

In my old system, I was already having desktop freezes on some heavy I/O operations like apt-get dist-upgrade and copying 4 GB video files. But now, it has become a lot worse: any apt-get install is ...
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72 views

Linux + how to know why Linux machine is hung from the messages on the console

As the picture below , my VM Linux machine was hung and I cant login how to identify the reason for the "hung" according to the messages on the console? I also searched more info from the /var/log/...
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2answers
50 views

Efficient way to deploy a custom kernel onto multiple hosts

I recently had to do a custom build of the Linux kernel from its source. That custom kernel is now installed on the machine I used to build it and works fine. Now there are other similar systems (i.e....
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How to interpret some kernel OOPS output?

I'm trying to analyze some kernel OOPS message. I'm able to understand most of the output, but there's still some lines that I have no idea how the should be interpreted. The first thing is PGD which ...
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CentOS 7 unable to cleanly umount a bind mount using rbind and rslave

The following sequence of commands will fail on CentOS 7 (kernel version: 3.10.0-327.10.1.el7.x86_64): [hidden]$ mkdir -p A B/a C/b [hidden]$ sudo mount --bind A B/a [hidden]$ sudo mount --rbind B C/...
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227 views

Find Linux kernel build date/time?

In a Linux distro, let's say Ubuntu 14.04, how can one find the time and date when this particular Linux Kernel was compiled/built?
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67 views

module not loaded at boot

I'm on an archlinux 4.4.1-2 and I'm trying to set up a netctl service. Problem is that for netctl to work I need to have bcma and b43 loaded. Since these two are not out-of-tree modules I thought I ...
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86 views

why process running in kernel mode cannot be preempted [duplicate]

I read that user mode process are preemptive but why not kernel mode process?
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202 views

Differences between system processes, and user processes, kernel control paths and kernel thread

My understanding is that a process always runs in user mode and uses user space only, and a kernel always runs in kernel mode and uses kernel space only. But I feel that I might not be correct, ...
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How does vfs_write decide to aio_write of which file system?

We know that sys_write call vfs_write that ultimately call fs->f_ops->aio_write.But how does kernel know which filesystem's aio_write call back function to call?? Moreover I have noticed that ...