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

learn more… | top users | synonyms

6
votes
0answers
59 views

md raid5: translate md internal sector numbers to offsets

TL;DR summary: Translate an md sector number into offsets(s) within the /dev/mdX device, and how to investigate it with xfs_db. The sector number is from sh->sector in ...
6
votes
0answers
179 views

Why are slab objects not reclaimed automatically

Everyday after a full system backup, various programs are failing with read errors until I run echo 2 > /proc/sys/vm/drop_caches to free reclaimable slab objects. For example, here's the output of ...
5
votes
0answers
116 views

Where in GRUB2 source code is the handover/jump to kernel code?

I'm looking for the line of code where GRUB2 finally jumps to kernel code and thus hands over execution on x86 systems? I guess it's in an assembler file since this is very low architecture stuff. I ...
4
votes
0answers
294 views

Kernel - Measuring the rate of timer interrupts

I am working on optimizing kernels of my boxes for telephony, which involves (among other things) adjusting the HZ rate and the preemption model. Initially the kernel was compiled with the default ...
4
votes
0answers
527 views

How to create Linux Kernel Headers from Linux Kernel Source?

I'm working with Tiny Core Linux and attempting to install Vmware Tools, which of course needs the Kernel Headers :-). It does not appear they have the Kernel Headers readily available in a package, ...
4
votes
0answers
486 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: ...
4
votes
0answers
1k views

update kernel without restart

Recently Linux got a new feature called Live Kernel Patching, which you means you dont have to restart your system to update kernel. Is there any other kernel which has this feature already or Linux ...
4
votes
0answers
413 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 ...
4
votes
0answers
419 views

Why are block sizes limited by page size in Linux?

In many (all?) file systems that Linux uses, including ext2/3/4, the maximum block size is the page size of the architecture Linux is running on, ie. 4KiB on x86. Why is there this limit? Might this ...
4
votes
0answers
431 views

EDID Invalid on USB DisplayLink Device

I have a Sabrent USB to HDMI adapter which is a DisplayLink device. It's recognized by udl as being a DisplayLink device, yet seems to be rejected/disabled due to having an invalid EDID: ...
4
votes
0answers
971 views

How extended (4MB) and regular (4KB) paging coexist?

On x86 architecture, "Extended paging" allows page frames (physical memory) to be 4 MB instead of 4 KB. The book "Understanding the Linux Kernel, 3rd" at chapter 2 "Memory Addressing", sub-chapter ...
3
votes
0answers
25 views

Does linux do outer ip fragmentation

I am looking to understand if Linux has the capability to do fragmentation of the outgoing packets at inner ip or outer ip level? I looked the source code in /net/ipv4/files in Linux kernel source, ...
3
votes
0answers
36 views

What process state(s) is counted into cpu time?

Two observations of mine (correct me if wrong): In the output of time for timing a process, 'User' and 'Sys' come from wait (2) or times (2), depending on the particular system. In Linux ...
3
votes
0answers
29 views

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 ...
3
votes
0answers
67 views

FIPS mode, signature verification failed

I am building a kernel with FIPS mode on. I followed most of the procedures described on Red Hat documentation here. I also created a hmac signed .vmlinuz file. After installing dracut-fips and ...
3
votes
0answers
32 views

Enumerate valid values for mknod

I have access to an embedded device which has a bunch of block/char files under /dev. However, this is not a satisfying description of the hardware, because since the firmware is shared with small ...
3
votes
0answers
41 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 ...
3
votes
0answers
73 views

Linux Angstrom can't start without serial cable plugged

I'm using the Altera Cyclone V Soc dev Kit and Linux Angstrom provides by rocketboards (http://rocketboards.org/foswiki/Documentation/GSRD141) Kernel is : 3.10 LTSI Linux can't start if any serial ...
3
votes
0answers
256 views

How to read the output of the show-memory-usage SysRq?

I couldn’t find any (recent) documentation on reading the output of the show-memory-usage SysRq (Alt+SysRq+m). So what can one learn from looking at it? Here is an example output form my box (Kernel ...
3
votes
0answers
93 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 ...
3
votes
0answers
154 views

How to insert a modified ELF loader given the current ELF loader is present?

I need to modify the ELF loader's kernel implementation of an Ubuntu 14.04 distribution. Having downloaded the sources using: sudo apt-get source linux-image-$(uname -r) I ran the configuration ...
3
votes
0answers
995 views

Can a zImage be used with U-Boot and ArchLinuxARM?

I am using U-Boot on a Cubieboard 2, sun7i AllWinner A20 board to boot into ArchLinux ARM. The kernel version that I have is the sun7i latest, which is 3.4.103-5-ARCH so, in kernel terms, it's a bit ...
3
votes
0answers
424 views

How to prevent kernel or any broadcast messages from flooding the TTYs?

Because of some hot-plugging issue, similar to what talked of here, the TTY displays show a continuous stream of messages (which are also logged in the /var/log directory). Every text I key in flows ...
3
votes
0answers
419 views

Some questions compiling linux kernel with make-kpkg

I'm doing my first steps compiling the linux kernel and adding a new system call. I've managed to do it, but I still have some questions. For this task, I has set up a Virtual Machine guesting debian ...
3
votes
0answers
1k 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 ...
3
votes
0answers
335 views

How to set CONFIG_PREEMPT_NONE in RHEL 6.4 (linux)

I am trying to tune the RHEL6.4 Kernel to handle server style load for of my application. With RHEL 6 scheduler has been changed to CFS and with RHEL 5 my application works fine. I would like change ...
3
votes
0answers
337 views

My SMDK2416 (for s3c2416) kernel works on 64MRAM but crashed on 128M

I'm currently working on embedded arm linux with smdk2416(s3c2416) The kernel is working on the 64MRAM. Recently, I need to increase the RAM from 64M to 128MB with 64MB on bank0 and 64MB on bank1. ...
3
votes
0answers
1k 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 ...
3
votes
0answers
2k views

CFLAGS in Linux kernel makefiles: which one is used when?

I'm not familiar with Makefiles, I can kinda understand them, but with the Linux Kernel I have a question. (Using 3.7.1, Patched with BFS so line numbers may be a bit off) On line 248 HOSTCFLAGS ...
3
votes
0answers
430 views

When would I use FBDEV vs DRM vs DSS?

I'm new to Linux graphics, and I'm interested in developing a graphics driver. I see that Linux supports three methods for writing graphics to the display device FBDEV DRM DSS2 When would I use ...
2
votes
0answers
40 views

How do Linux kernel modules get enabled in a Linux distro's kernel package?

Although I know how to recompile my kernel to enable a module I want, I'm curious to know how the default Linux kernel modules are chosen in a Linux distribution's kernel package. Taking a comparison ...
2
votes
0answers
43 views

How to compile custom kernel for Raspberry Pi

I'm trying to run the Ubuntu 14 Raspberry Pi ARM image in QEMU, and for that I need the kernel that matches the version used in the image. If I mount the image and run file vmlinuz I see: vmlinuz: ...
2
votes
0answers
20 views

Cannot create 16-bit LDT segments on kernel 3.8.11

Running Crossover, I get the warning, Your system does not allow creation of 16-bit LDT segments. I am aware that this was a problem around kernel 3.1.x, but I am on 3.8.11. Also, the fix suggested in ...
2
votes
0answers
22 views

How connected are kernel modules to kernel version?

I'm wondering how custom ROMs port new versions of Android (particularly the Linux kernel) to old phones. As I understand, Linux allows closed source kernel modules. If so, then when the phone ...
2
votes
0answers
30 views

how to build kernel-tools-4.2.xx.rpm and kernel-ltools-libs-4.2.xx.rpm

I am trying to upgrade Centos-7 kernel (kernel-3.10) to (Kernel-4.2.6) and for that I downloaded kernel from kernel.org and create rpm for the custom configuration (arch x86_64)using "make rpm". ...
2
votes
0answers
752 views

Why can't the kernel run init?

I've downloaded the Raspbian image on this page. I'm trying to compile a kernel that can be used to boot the image within qemu. I downloaded the Linux kernel source from kernel.org and ran: make ...
2
votes
0answers
41 views

Does Linux still use rootfs?

In the kernel documentation file "ramfs, rootfs, and initramfs" it says Rootfs is a special instance of ramfs (or tmpfs, if that's enabled), which is always present in 2.6 systems. I have not ...
2
votes
0answers
58 views

What hardware support is needed for linux to do `gettimeofday` / `clock_gettime` in userspace using `hped`?

On reasonably modern systems Linux can service "system" calls like gettimeofday and clock_gettime entirely in userspace through the linux-vdso.so (or linux-gate.so) virtual library, so it does not ...
2
votes
0answers
241 views

Errors cross-compiling with distcc

I'm currently attempting a build of the Raspbian kernel using both a cross-compiler (for the Raspberry Pi 2's ARM processor) and distcc, based on the instructions posted at the Raspberry Pi website. I ...
2
votes
0answers
363 views

Virtualbox and GPU Pass-trough: Device with host PCI address already attached to this VM

I have server with several GPUs. My idea is to attach them to different VMs in order to use that VMs in CUDA (or OpenCL) calculations. My setup: CPU: Intel Xeon E5-2670 GPUs: 1 x Radeon HD 7970 ...
2
votes
0answers
22 views

Use netconsole to debug with kernel crash

Recently I use netconsole to debug with kernel crash. However the log prints too fast, it seems that netconsole cannot transfer all the log in real-time, since ehternet allows maximum payload of each ...
2
votes
0answers
45 views

What does Linux wait for when switches from Xorg to text console?

Sometimes my Xorg hangs and locks the console dead, with a “stale frame” of GUI on the monitor. Hardware and driver-related problems are likely (see here for description of particular configuration), ...
2
votes
0answers
41 views

Replacement for cap-bound

We have an old Linux from scratch kernel used in one of our systems, that uses the old cap-bound mechanism (modifying /proc/sys/kernel/cap-bound) to restrict the capabilities of the system. This was ...
2
votes
0answers
203 views

How to resolve dracut problem when intall Fedora 21

I'm Ubuntu User. But I wanted to change my OS from Ubuntu to Fedora. So I wanted to Fedora 21. But there is a problem. I'm using USB Drive to boot Fedora 21. When I try to install Fedora I get a ...
2
votes
0answers
36 views

How to work with a kernel one has no information about?

I'm working with a system to automatically assemble Live CDs. It came packaged with a kernel (seemingly based on 3.13.11), that has been working without problems so far. I noticed that, when I try ...
2
votes
0answers
435 views

Can I make the boot even more verbose than loglevel=7 using kernel parameters?

I have an error when booting on a machine, my machine is stuck with the error message: Booting a command list. I can see this message when I add loglevel=7 and only if I delete the quiet in the ...
2
votes
0answers
1k views

How to rotate the LCD screen/framebuffer to 180 degree?

I have a custom board with a Freecale i.MX6Q SoC. I am using Linux kernel 3.03.35 and LCD is 3.5 inch RGB type display. I want to rotate my LCD screen to 180 degree. I tried a lot to pass parameters ...
2
votes
0answers
176 views

Meaning of an ampersand prefix in a device tree

I am looking at a DTS file which tries to specify different nodes, but interestingly I find a few nodes having different style of nomenclature. / { model = "TI AM335x BeagleBone Black"; ...
2
votes
0answers
55 views

Is there support for flattened device tree in Sparc 32 port of the Linux kernel?

We are trying to write a minimal bootloader for booting the linux kernel on a Sparc V8 processor simulator. From what I understand, the interface between the bootloader and kernel consists of a data ...
2
votes
0answers
195 views

“can't write to batman adv kernel file” while using “batctl p mac-address”

I installed batman-adv and batctl on Ubuntu 14.04.1. When I issue the comand: batctl p 00:16:bf:01:68:46 I get this error: Error - can't write to batman adv kernel file ...