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

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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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1answer
75 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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3answers
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What happens when I run the command cat /proc/cpuinfo?

What happens when I write cat /proc/cpuinfo. Is that a named pipe (or something else) to the OS which reads the CPU info on the fly and generate that text each time I call it?
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1answer
29 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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106 views

how to check a kernel version which was used when building package

I use apt when downloading packages from Ubuntu repositories. How can I check which kernel version was used when building package? When it is important (kernel version of the build server vs. kernel ...
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1answer
158 views

USB keyboard is disconecting automatically (without being unplugged)

In my log, I see following message: kernel: usb 1-1.6: USB disconnect, device number 5 acpid: input device has been disconnected, fd 7 acpid: input device has been disconnected, fd 8 I have not ...
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282 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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3answers
2k views

How can I create my own distro and include a custom kernel & packages? [closed]

I wanted to know how to add packages to the Linux kernel and then package it to a ISO or CD for friends. Thanks in advance and please don't point me to LFS - Linux From Scratch!
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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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1answer
96 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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1answer
18 views

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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2answers
2k views

How do you install the FreeBSD10 kernel sources?

I am trying to run an update of freebsd10 and I am being asked for the kernel sources ===>>> Launching child to update lsof-4.89.b,8 to lsof-4.89.d,8 ===>>> All >> ...
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1answer
158 views

Does this bug indicate an error in my btrfs filesystem of simply a bug in the 4.2.0-RC5 kernel?

I'm not sure this is the right place to ask this... I have been running a pre-release kernel (4.2.0-rc5) and yesterday had a possible disk error on my 6-disk raid-1 btrfs filesysystem. While trying ...
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1answer
834 views

Linux kernel: task vs thread

When I was reading a book(Linux kernel programming), I found an interesting/confusing paragraph about mm_segment_t addr_limit(one of the member in struct_task) as shown below: mm_segment_t ...
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5answers
12k views

Use of O_DIRECT on Linux

If this question is too programmer oriented, let me know. I wonder if there are people familiar with the O_DIRECT flag for the open() system call on Linux 2.6? Linus disparages its use, however high ...
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1answer
52 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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2answers
117 views

Booting into a kernel image

I have a recently-compiled Linux kernel image (vmlinuz file) and I want to boot into it. I am aware that this won't give me a familiar Linux system, but I am hoping to be able to at least run some ...
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3answers
65 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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udev usb stick device list

We have 2 different yocto distributions: ARM Kernel 3.10.53 X86 SMP Kernel 3.10.0 If we add a USB stick to the ARM system we get different udev messages. usb/usb_device usb/use_interface ...
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1answer
47 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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1answer
163 views

Huge Pages on CentOS 6.6

Recently I installed CentOS 6.6, but when I tried to configure Huge Pages, I cannot see the common paths that I am already using to configure hugepages in other CentOS 6 machines, but with the 2.6 ...
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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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1answer
238 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
155 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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1answer
83 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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3answers
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yum installs kernel-devel different from my kernel version

I am attempting to install the VMWare player in Fedora 19. I am running into the problem that multiple users have had where VMware player cannot find the kernel headers. I have installed the ...
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1answer
34 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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2answers
71 views

Error when booting new kernel - overlays [closed]

I'm trying to boot my first custom kernel from Linus's latest repo: During the decompressing stage I get the following error: Could not find overlay #6 ### dt-test ### of ...
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2answers
38 views

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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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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1answer
126 views

How do I crash Ubuntu Linux 14.04 LTS deliberately?

I'm trying to crash an instance on AWS so that I can simulate what happens when it gets 'stuck'. I tried the top suggestions here How to cause kernel panic with a single command? but unfortunately ...
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Linux: Two different drivers for two (mostly) identical PCI devices

For some obscure reason, I want to use two different drivers for two identical PCI devices on the same system. The drivers have different characteristics, which is why I want one physical device ...
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602 views

Uboot passes arguments to kernel!

How can uboot pass command line argument to kernel? I did some googling and got to know that it uses the bootargs environment variable. There it was mentioned that setenv bootargs key=value. Since I ...
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2answers
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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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1answer
307 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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1answer
49 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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Recompile the kernel changing only one option

I've already built a custom kernel based on the mainline 4.1.6. Now I want to disable CONFIG_ACPI_I2C_OPREGION The kernel build is not very short, so I'd like to rebuild only the parts affected by a ...
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4answers
242 views

decrease kernel boot log verbosity level

When my kernel boots, apart from the useful important information, it prints lots of debugging info, such as .... kernel: [0.00000] BIOS-e820: [mem 0x0000000000000000-0x000000000009d3ff] usable ...
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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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Moving HD from one machine to another

About two hours ago I had a Lenovo X220 w/Evo 850 SSD containing a CentOS 7 installation on it (yes, a server distro on a laptop - I know, but I'm familiar with RHEL). Several weeks back I'd completed ...
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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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Understanding the relation between FreeBSD kernel configuration file and actual device

To my understanding, FreeBSD's kernel is configured via text files. Each kernel configuration entry is on a single line. Many entries also have comments set off with a hash mark. The GENERIC conf. ...
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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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146 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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1answer
178 views

How does FreeBSD allocate memory?

I am aware that this is simplified/generalized explanation, but top(1) utility divides memory in FreeBSD into six pools- Active, Inactive, Wired, Cache, Buffers and Free. Example from top(1) output: ...
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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: ...