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

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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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1answer
236 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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1answer
687 views

How to troubleshoot high kernel time (high network usage; high interrupts)

I've noticed that I have high kernel time when doing a lot of network traffic in Linux. I also noticed that 45% of my CPU is spent doing interrupts. How can I further troubleshoot this?
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2answers
61 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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0answers
182 views

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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1answer
89 views

What is the difference between micro-kernel and monolithic-kernel? [duplicate]

I heard that Unix/Linux is a monolithic-kernel whereas Hurd is micro-kernel. So, I want to know what is the difference between these kernel type?
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67 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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2answers
3k views

How can I check my kernel preemption configuration?

I want to check if my Linux kernel is preemptive or non-preemptive. How can I check this using a command, something such as uname -a?
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40 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
98 views

How to install kernel sources

I 'm running Angstrom distribution (console only) on BeagleBoard-xM. Image was build on Narcissus, with Bootloader Files (x-load/u-boot/scripts) added. I noticed that usr/src directory is empty. I ...
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225 views

I installed linux. And it doesn't recognize usb keyboard and mouse

When I boot computer with kernel 2.6, I can use usb keyboard and mouse. But If I use kernel 3.10, It doesn't work. With kernel 2.6 $ lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root ...
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14k views

Where to download Linux Kernel source code of a specific version?

Is there a resource to download a specific kernel version source? For example, I want to get 2.6.36.2 sources to compare with this package and see what changes were introduced?
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1answer
41 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
12 views

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
186 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
59 views

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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2answers
3k views

dmesg: pci BAR 7: can't assign io

I have VMware virtual machine running Debian Wheezy. I have compiled my own kernel 3.14. I have noticed dmesg is flooded with messages pci BAR 7: can't assign io (size 0x1000). I have no idea what ...
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2answers
59 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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1answer
35 views

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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0answers
87 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
70 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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1answer
132 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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3answers
38 views

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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525 views

Why do people call Linux a kernel rather than an OS?

Why do people refer to Linux as a kernel rather than an operating system? To the best of my knowledge, the kernel is one part of the operating system.
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68 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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2answers
3k views

how do I safely delete old kernel versions in CentOS 7?

I might be encountering odd symptoms resulting from competing kernels in CentOS 7. So how do I safely delete the old kernels? And how do I know which kernel is the newest one? Below is the ...
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2answers
1k views

Removing the rescue image from /boot on fedora

I am trying to upgrade my fedora system (21 → 22) using fedup. I removed all old kernels using package-cleanup but fedup still needs 2MB more on /boot. These are the files in /boot: -rw-r--r--. 1 ...
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1answer
47 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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3answers
689 views

Cannot mount eCryptfs

I tried to install eCryptfs on my server to open an eCryptfs I did on my home computer. I got these errors. $ sudo mount -t ecryptfs /home/(place)/enc/ /home/(place)/enc/ Unable to get the ...
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1answer
56 views

Block device disappears after suspend-resume

After few suspend/resume cycles one of my hdd disappears from the list of devices, here is part of dmesg output that seems to be related to issue: [ 450.005310] sd 5:0:0:0: [sdc] Starting disk [ ...
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155 views

Is there a general USB 3.0 support in OpenWrt?

the only information i found about this topic is outdated since 2011/02: it says there is no support for devices with usb 3.0 "so far"! according to the german wikipedia since version 2.6.30 the ...
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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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1answer
111 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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1answer
109 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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32 views

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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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
275 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 TOS=...
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1answer
11k views

Centos 7.1 still using outdate kernel 3.10 how to upgrade to kernel 4.0

I'd like to upgrade my Centos 7.1 kernel from 3.10 to 4.0 i did successfully in Ubuntu 15.04 using Linux 4.0.1-040001-generic even though i updated it manually it's works fine so please could ...
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1answer
74 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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52 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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78 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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2answers
174 views

Module vfat fails to load (I've tried the obvious fixes)

The module vfat doesn't load on boot, and attempts to force the issue with a modprobe vfat produce the error modprobe: ERROR: could not insert 'vfat': Unknown symbol in module, or unknown parameter (...
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51 views

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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1answer
127 views

How does linux load firmeware for built-in driver modules

I've learned that the firmware-subsystem uses udevd to copy a firmware to the created sysfs 'data' entry. But how does this work in case of a built-in driver module where udevd hasn't started yet? I'...
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295 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?