The kernel of operating systems popularly known as Linux, or sometimes GNU/Linux.

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Where do these boot log entries come from and who creates them?

I'm wondering what kind of code writes these first two lines into /var/log/syslog while booting my machine: Aug 4 10:13:48 HOSTNAME kernel: imklog 5.8.11, log source = /proc/kmsg started. Aug 4 ...
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2answers
48 views

Wrong eUID in `/proc/PID/status` when SETUID is used

While doing a wargame challenge, I ran into an issue with permissions. The info given by /proc/PID/status is not in adequation with the permissions that should be given to the processus. I am user ...
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1answer
3k views

bnx2: Can't load firmware file “bnx2/bnx2-mips-09-6.2.1b.fw”

I just compile the kernel 3.10.19 from kernel.org Support for bnx2 is enable. On my server when I try to start the eth0 interface I got the following error : bnx2: Can't load firmware file ...
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0answers
19 views

How to troubleshoot Fedora kernel bug

Bug 1236215, reported to the Redhat bugtracker has not gotten any attention in over 3 weeks. I'm trying to track down the cause myself, but I'm not sure how to proceed. The problem was introduced in ...
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19 views

provisional kernel page table confusion [on hold]

I have a question while studying “Understanding the linux kernel, 3rd ed.” chp2, ‘provisional kernel page tables’ section (p.69). In the example, it assumes kernel’s segments, the provisional page ...
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1answer
3k views

Configuring, compiling and installing a custom Linux kernel

I'd like to try using a kernel other than the one provided by my distro -- either from somewhere else, or as customized by me. Is this difficult or dangerous? Where do I start?
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1answer
12 views

Increasing Kernel Mode Setting (KMS) scrollback buffer size

I'm using Kernel Mode Setting to set my server's tty resolution. I added GRUB_GFXMODE=1280x1024x24,auto to /etc/default/grub, and GRUB_GFXPAYLOAD_LINUX=keep was already there. There's no vga= or ...
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1answer
566 views

custom kernel and firmware loading

After I have compiled my kernel, and when I type make modules_install, not only are the modules copied into /lib/modules/ but also firmware is copied into /lib/firmware/. The following is the end of ...
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1k views

When do I need to specify add_efi_memmap as kernel argument in UEFI/EFI boot?

I am reading some tutorials how to EFI stub (efistub) load the Linux kernel. These instructions often use kernel boot parameter add_efi_memmap. The intended hardware is Intel x64 having 8GB of RAM. My ...
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1answer
34 views

Is it possible to delay booting the system after the user has pressed the power button? [closed]

I want to delay the time to load the kernel after the user has pressed the power button by 10 seconds. Reasons for this is a machine we have built which requires other components to start sending data ...
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1answer
61 views

what's difference between src version 3.* and 3.*-generic

In my local Linux/Ubuntu, I have two directories for Linux src /usr/src/linux-3.16.0 /usr/src/linux-3.16.0-generic I found the code in 3.16.0 is much more than that in 3.16.0-generic. I am ...
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1answer
44 views

Unable to install new kernel in ubuntu server. “gzip: stdout: No space left on device” error even though abundant disk space

I am trying to install a new kernel on Ubuntu Server and I am unable to complete it due to a "gzip: stdout: no space left on device" error. The full error was produced after running sudo make ...
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2answers
23 views

Uboot pass arguments to kernel!

How uboot can pass command line argument to kernel? I did some googling and got to know that it uses bootargs environment variable.There it was mentioned that setenv bootargs key=value.Since I am ...
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1answer
26 views

Recompile kernel without modules that are not currently in use

Is there a neat way of stripping the Linux kernel to only support the devices that are currently in use. After NVIDIA complaining about GCC version mismatch, I decided to recompile the kernel with the ...
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7answers
23k views

Linux Kernel: Good beginners' tutorial [closed]

I'm interested in modifying the kernel internals, applying patches, handling device drivers and modules, for my own personal fun. Is there a comprehensive resource for kernel hacking, intended for ...
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0answers
12 views

What is the Linux scsi mid-layer

In the Linux storage stack there are 3 levels: upper, mid and lower. Therefore, I know what it is in that sense. What I'm hoping someone will know is, what files in the Linux source tree actually ...
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0answers
20 views

How to send signal from kernel to user space [migrated]

My kernel module code needs to send signal [def.] to a user land program, to transfer its execution to registered signal handler. I know how to send signal between two user land processes, but I can ...
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1answer
26 views

Kernel address space layout

Userland address space is well documented, which includes segments like heap, stack, .text, .bss, etc. But there is not enough documentation on kernel address space. Since certain virtual address is ...
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22 views

Kernel config diffs - better way to maintain

I maintain one Linux distro (LEAF) with multiple kernel targets, so it needs to have multiple kernel configs (one reference config + usual patch files for other targets). But this adds headache on ...
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1answer
78 views

RAM Disk related questions [duplicate]

there is a developed kernel subsystem that needs a chunk of memory allocated to itself that only it could manipulate this chunk. this memory should be physically contiguous and also it need the access ...
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1answer
372 views

CDC ACM doesn't working in a custom linux kernel

I've a cubieboard2 running arch linux with a custom linux kernel. In the cubieboard2 I plugged in my usb-serial device (like an arduino), the device is recognized as CDC ACM. My linux kernel has the ...
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2answers
794 views

No build scripts available when compiling module outside of Linux source tree

I am attempting to build a basic module outside of the Linux source tree (3.18.0-rc6). When I build it, I get an error saying it couldn't find scripts/... My directory setup looks like this ...
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17 views

CPU Handling with Delayed Work [migrated]

Hey so I'm looking at this function in the kernel source code. I'm trying to figure out how Linux handles the situation where a task cannot be scheduled on the local CPU. /** * queue_delayed_work - ...
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1answer
2k views

How to fix make error “No rule to make target 'menuconfig'” when building a kernel for Beagleboard?

The aim is to build and install the USB Video Class (UVC) module, via make modules_install. I'm trying to configure the kernel via make menuconfig on Angstrom distribution, running on BeagleBoard-xM. ...
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Debian instance has two Kernels after installing Intel PCIe SSD drivers - one with Black screen

I am using Debian 8 and after installing Intel PCIe ssd drivers I noticed that the are two kernels. The kernel which has the Intel drivers installed does not display the desktop, only a black screen. ...
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1answer
640 views

DisplayPort and Intel HD cause GPU hangs

My system has problems with the displayport connection. This is indicated by several problems that, at the first glance, do not have anything in common. The reason why I claim DP for beeing the cause, ...
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1answer
582 views

Device eth0 does not seem to be present, delaying initialization

I have cloned a fedora and now trying to configure network interfaces. Every time i am adding a new NIC, it starts with number eth3 (rather eth0). i have tried removing and modifying the ...
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1answer
175 views

/dev/mmcblk0 partitions limit

I've just mounted a microSD card which has 17 partitions in my laptop and I'm getting the following error in the YaST partitioner: Your disk /dev/mmcblk0 contains 17 partitions. The maximum number of ...
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1answer
25 views

Linux kernel build : shouldn't make <manufacturername>defconfig yield the same .config file?

I'm building a cross compiled 3.2.15 kernel for a Marvell Armada 370 system. The vendor's default config file for this is armada_370_v7up_defconfig. So when I perform a make ...
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0answers
30 views

Why does Linux scheduler have locks for run queues?

Why does Linux Kernel Scheduler code have locks for run queues? Does the scheduler spawn kernel threads, and locks are to prevent two of such threads to avoid modifying run queues at the same time?
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3answers
55 views

How Linux kernel gets build [closed]

I am new to Linux and I would like to know how the Linux kernel gets built ? Who builds this ? I have heard that Linux gets build by programmers sitting all over the world. But it gets only released ...
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1answer
35 views

NMI received for unknown reason 20 — Do you have a strange power saving mode enabled?

I am using Debian GNU/Linux 7.8 (wheezy). While running my MATLAB program today, I got this message in terminal. Message from syslogd@sas21 at Jul 18 16:40:49 ... kernel:[1747708.091929] Uhhuh. NMI ...
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1answer
27 views

Is a disabled kernel option equivalent to not loading the corresponding module?

Suppose I set a tristate kernel configuration option to be built as a module, but I don't load the corresponding kernel module at runtime (and it doesn't get loaded automatically). Is the ...
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1answer
25 views

edit module requirements when compiling kernel

I would like to compile the realtime kernel for raspberry pi (https://github.com/emlid/linux-rt-rpi) and want to use the pi with a soundcard - the tascam us122l. The problem that I have is the ...
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5 views

Opening/Writing to a file from a KProbe handler [migrated]

I am writing a Linux kernel module using Kprobes to trace specific system calls, and I need to write to a file from within a KProbe handler (specifically, a Kretprobe). I know this is generally not ...
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Why am I able to compile kernel modules without “#include”ing the relevant header files?

Based on the common practices shouldn't I have to include <linux/stat.h> and <linux/module_param.h> in the following program? #include<linux/module.h> char str[7] = "hello"; int ...
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966 views

Kernel does not detect Hardware / Software or Hardware fault

I've got more of a basic question for you: My linux kernel (I tried several here from stock 2.6, 3.2 and 3.5 as well as a custom 3.7.3 one) does not detect my synaptics touchpad - or I'am too dumb ...
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465 views

Enabling GPIO in kernel not working [closed]

I have tried to enable the GPIO pins for my system through the Kernel but I am not able to get them to work. When I try this: echo 1 > /sys/class/gpio/export The terminal window just closes. ...
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0answers
217 views

Corrupt LVM metadata header after kernel update

I'm running Debian Wheezy (Linux wheezy3.2.0-4-amd64 #1 SMP Debian 3.2.63-2+deb7u1 x86_64 GNU/Linux) as an encrypted LVM with hardware raid 1 (Adaptec 6405E) on a supermicro server. I was encounting ...
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279 views

Linux kernel dropping custom keyboard scan codes

I have a vintage IBM 122 key model M keyboard that I am adapting for use on a modern computer. I am using a Teensy 2.0 to do the encoding and to handle the USB side of things. I borrowed the firmware ...
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0answers
737 views

Debian driver needed for Intel ICH7M SouthBridge I/O controller

I am using a motherboard based on this architecture. http://www.intel.com/content/www/us/en/intelligent-systems/navy-pier/embedded-intel-atom-n270-with-mobile-intel-945gse-express-chipset.html I ...
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0answers
148 views

Can I masquerade a kernel uevent?

What I think happens From my understanding this is what happens when I connect a USB device to my computer: Kernel recognizes that I plugged in a USB device Kernel setups the very low-level things ...
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0answers
72 views

Problems with file system

I created a partition with EXT4 file system and when I'm writing in this partition frequently the Kernel return the following error: Jan 01 01:17:54 infobuffer360 kernel: r7:c0561280 Jan 01 01:17:54 ...
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229 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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Giving S_IWUGO permission to module parameter results in compilation error (while S_IRUGO or S_IXUGO doesn't) - why? [migrated]

I wrote a simple kernel module to learn module_param feature of the kernel module. However, if I give the S_IWUGO, S_IRWXUGO or S_IALLUGO permissions for the perm field, I get the follwing ...
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2answers
4k views

Error while installing wireless-bcm43142-dkms-6.20.55.19: dependency linux-headers is not satisfiable

I have to install a .deb file with the firmware for the wifi card (This is the name of the file: wireless-bcm43142-dkms-6.20.55.19_amd64.deb; I've downloaded the file from here: ...
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1answer
85 views

Is the device tree compiler tied to the kernel version?

I have a situation in which same device trees are used with different kernels. Can the device trees be build only once and used with all kernels? The reason I ask this is because I found the device ...
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4answers
767 views

Using real time kernel headers to compile userspace code vs default headers

Per customer requirements, I installed CentOS 5.6 with the default kernel. With this kernel installed, the time.h file includes the #define CLOCK_MONOTONIC. Now, a real-time kernel was installed ...
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1answer
24 views

Difference between Current and RC Kernels?

What's the difference between wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.2-rc1-unstable/linux-headers-4.2.0-040200rc1_4.2.0-040200rc1.201507051635_all.deb and wget ...
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1answer
596 views

Determine whether kernel built-in driver supports a device

I'm trying to find a way to accurately determine whether all the hardware on some system has a valid driver installed either via a kernel module or built-in to the kernel. I'm working with RHEL 5.5 ...