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

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Diagnosing regular crashes with data loss?

I'm on Kubuntu 15.04 on a HP zBook 14. Every few days, my computer locks up completely - screen stays on, sound get stuck and plays the last few tenths of a second of what ever was playing over and ...
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280 views

Installing Linux onto Teclast X80H x86 tablet

I'm trying to install Linux (any linux, but preferrably Ubuntu Mate) onto my cheap tablet Teclast X80H, which came preinstalled with WIN8/Android x86. Main specs are: CPU: Intel Bay Trail, 1830 MHz, ...
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186 views

Why cgroup cpu items are miss in Debian 8

the kernel version for debian 8 use 3.10. But under /sys/fs/cgroup/cpu, miss a lot of cpu items. vagrant@debian-jessie:/sys/fs/cgroup/cpu$ ls -1 . cgroup.clone_children cgroup.procs ...
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no bios, black screen on laptop after kernel upgrade and hibernation

I am running dual boot Windows 7 and Linux Mint 17.2 on an ASUS K56. I upgraded the kernel to 4.2 the other day. Reboot and everything worked just fine. Tested browser, music player etc. Then I leave ...
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sysfs alternative to /proc/acpi/button/lid/LID/state

As you probably know ACPI procfs is deprecated in new kernel versions and with sysfs I don't know of a clean way of reading the state of the lid button. The only way I've come up with is hooking up ...
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How do I configure a systemd service to execute simple /bin/echo “Hello world” command to show the output on the console?

I am trying to boot up a vm with qemu-system-ppc64(similar to lkvm). I am using the following command: qemu-system-ppc64 --enable-kvm -vga none -nographic -nodefaults -chardev stdio,id=id1 ...
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When will Debian switch to Linux 4.x? ( and support the live kernel patching ? )

Wikipedia says that current Debian 8.2 Jessie is based on kernel 3.16.0, so I was wondering when a native version based on kernel 4.x would be released and if the live kernel patching will be there as ...
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56 views

How to find hugepage size on system?

I am getting following two different result. which one i should consider for Hugepage? [root@server ~]# getconf PAGESIZE 4096 [root@server ~]# grep -i hugepagesize /proc/meminfo Hugepagesize: ...
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136 views

Appending files to initramfs image - reliable?

I'm modifying a bunch of initramfs archives from different Linux distros in which normally only one file is being changed. I would like to automate the process without switching to root user to ...
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25 views

Unable to view printk output

I have been trying to debug my kernel code with printk statements. But the messages does not show up on the console. cat /proc/sys/kernel/printk gives 7 4 1 7. What could be the reason?
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Why number of dirty pages is always 0 on 2.6?

In /usr/src/linux/Documentation/filesystems/proc.txt i've found the string: Table 1-3: Contents of the statm files (as of 2.6.8-rc3) ...
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Map non-standard hid reports to scancodes for Logitech G105 Gaming Keyboard

So, I've recently purchased the named keyboard and have been doing some reverse engineering as to how the Logitech Gaming Software does things with it. In this process I've discovered that a few magic ...
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Only booting to GRUB automatically

I installed Elementary OS earlier as the sole OS on my machine. When I boot now, GRUB is displayed on the screen (with a message about minimal bash being available). I can boot to Elementary OS by ...
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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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Microkernel (e.g. GNU Hurd) more secure than monolithic kernel (Linux)? [duplicate]

I would like to understand (in relatively layman's terms) if and how a microkernel such as the Mach-based GNU Hurd is more secure than a monolithic kernel such a Linux. Additionally, does a ...
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149 views

How can Kernel 4.0 patch the system rebootless?

I've seen that new functionality mentioned in Linux kernel 4.0 was the ability to update without a reboot. Does this mean I can use my system with my application going, and the update will have no ...
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100 views

Hairpinning in linux

I have a router in which I installed a Linux system. I want my router supports NAT hairpinning Does a such feature exists in Kernel Linux? If yes how to activate it? Are there a patch to apply it on ...
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is it possible to add a Kernel Header file manually along with the kernel source and build

I am using Linux 2.6.18-238.e15. In this kernel source I could not find the kernel header file procinfo.h. But my application requires this header file. Is it possible to add this header file ...
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106 views

Linux Permissions UID 0 vs Ring 0

I am studying for a Computer Security exam, and I am struggling to understand the following sample question. 'Explain the difference between running in ring 0 on x86 and running as UID 0 in Linux. ...
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34 views

How do I store the data in disk directly in kernel module? [closed]

I capture the TCP packet in function of netif_receive_skb , I want to store the playload of TCP packet. we can't read/write the file in kernel module, so store in disk directly maybe a way? ...
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578 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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468 views

What's changed with USB drivers in 4.0 and later Linux kernels?

With kernels up to 3.19, all of my USB devices work perfectly. On upgrading to 4.0 or later, some of my USB devices stop working and the kernel produces errors like this: [ 3.369436] usb 9-1: ...
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How to run newly built Linux kernel in VirtualBox? [duplicate]

I found this question previously asked, but the reply doesn't satisfy me. I have just build Linux kernel which is inside: /arch/x86_64/boot/bzImage Now, how do I install it in VirtualBox or copy that ...
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32 views

passing file in mount options

I am writing a stackable file system which requires some database file. I am thinking of taking it as mount time argument and then reading it's content into private field of superblock of mounted FS. ...
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Does sysrq work when the kernel panic occurs?

I normally would test whether sysrq + sub works when the kernel panic occurs, but "unfortunately" my system works pretty stable, and I have no idea how to make kernel panic. So the question is very ...
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154 views

Magic number for new file system

I am writing new stackable file system, all the file systems have associated magic number which acts like their "signature" for file formats. I was wondering how to decide this number for my file ...
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56 views

How process know address of shared library?

As far my understanding, when I compile my C source code GCC/LD does the address binding at compile time. Typically this address starts at zero. When I call a function from shared library how the ...
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60 views

When does “/bin/rm” removes itself while issuing “rm -rfv / ” command?

When files are being deleted after issuing /bin/rm -rfv / command as root, how does rm continue to run even after /bin has been deleted? How does the kernel deal with this file system process?
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centOS7 kernel bug server getting freez

I am seeing this error in /var/log/messages, also sometime my network getting disconnect also.. couple ping drops.. is it a bug related to network tg3 driver? CentOS Linux release 7.1.1503 (Core) ...
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115 views

can not upgrade kernel

I use centos-7 x86_64 ,current kernel version is 2.6.32-042stab108.5 I try to upgrade kernel by these command: rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm yum install ...
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183 views

How to understand the modinfo output?

I'm just trying to understand the modinfo output that describes a kernel module. For instance, in the case of the module i915, the output looks like this: $ modinfo i915 filename: ...
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681 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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218 views

How to upgrade Kernel from 2.6 to latest?

I am currently running Debian 8.2 (I know this is for Ubuntu questions but I do believe the process is similar) And I can't seem to be able to upgrade my Kernel. The current version is: ...
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112 views

Kernel update - reboot needed or not?

I just updated our AWS Linux Server (which uses yum) and a new kernel is installed: kernel-4.1.10-16.27.amzn1.x86_64. It didn't state anything about restarting. According to this answer here I ...
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52 views

Setting up a single driver to be automatically compiled with DKMS from kernel tree

I'm on Ubuntu 14.04 with the HWE from Vivid, meaning I'm running kernel 3.19 for now, until 15.10 hits and the kernel is made available through HWE. I'm on a MacBook Pro and my particular Bluetooth ...
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Working my way through dmesg output on a custom 3.5.4 kernel

Having read this thread here: What does the Virtual kernel Memory Layout in dmesg imply? It sounds like 'lowmem' is exclusively meant for kernel-space. [ 0.000000] virtual kernel memory layout: ...
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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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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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How to figure out why Linux crashes

Every so often, my laptop will crash. The screen will freeze, including the cursor, the lock lights (caps lock and the like) will turn off if they were on, though my battery, power, and wifi lights ...
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What's the use of this empty function declaration in exec.c kernel source?

I see some empty functions in the Linux kernel file exec.c here: http://lxr.free-electrons.com/source/fs/exec.c#L235 But, some functions like free_arg_pages is again declared below here (with same ...
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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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How to know the path for a corresponding inode number

If i know the inode reference i.e. struct inode *inode; and struct dentry structure will be containing path information for a particular dentry in d_iname variable. How can I map from ...
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405 views

Removing/Purging linux-headers-3.16.0-30-generic, but apt-get wants to install linux-headers-3.16.0-50-generic

The command I am running is: apt-get purge linux-headers-3.16.0-30 linux-headers-3.16.0-30-generic linux-image-3.16.0-30-generic linux-image-extra-3.16.0-30-generic linux-libc-dev --assume-yes ...
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RHEL 5 Kernel Panic

I performed some fdisk operation on vmdisk. After rebooting I got the following error: unmounting old /dev unmounting old /proc unmounting old /sys switchroot: mount failed: No such file or directory ...
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Syn list length increase(backlog queue)?

How does backlog length increase follow way does not affect centos echo "net.ipv4.tcp_max_syn_backlog=1024" >> /etc/sysctl.conf I use centos 6.7
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module issues with kernel

I am currently getting this error message:- iptables v1.4.12: can't initialize iptables table `filter': Table does not exist (do you need to insmod?) Perhaps iptables or your kernel needs to be ...
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54 views

Qemu - debug new syscall

as a school project I have to add a syscall to the latest stable linux kernel. I did and recompiled the kernel using make defconfig and make. After going through several tutorials to boot the kernel ...
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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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255 views

Install USB2Lan Driver on Debian 8 (Jessy)

I've installed Debian 8 netinst. get make, gcc, linux-source-3.16 ... Here is the lsusb list: root@Filter:~/smsc7500# lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 005 ...
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system user + kernel time using /proc/stat

user: normal processes executing in user mode nice: niced processes executing in user mode system: processes executing in kernel mode idle: twiddling thumbs iowait: waiting for I/O to complete irq: ...