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

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6
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3answers
245 views

How does one capture traffic on virtual interfaces?

I would like to capture traffic on Linux virtual interfaces, for debugging purposes. I have been experimenting with veth, tun and dummy interface types; on all three, I am having trouble getting ...
4
votes
1answer
213 views

How we can avoid rebooting the system after partition change with fdisk?

When modifying the partition table, fdisk usually returns the following error message: WARNING: Re-reading the partition table failed with error 16: Device or resource busy. The kernel still ...
1
vote
1answer
192 views

High performance routing with high churn ruleset. What approach is most likely to scale to C10K and beyond?

I've been asked to create a high throughput router using PC / server hardware. I'm modestly familiar with pf, iptables, and tc, but I've never had such high churn and so many rules. I hope you can ...
1
vote
1answer
68 views

How to automate configuration of the Linux kernel build

I'm compiling a flavor of the Linux kernel based on the default configuration (for an ODROID system), with some additional features enabled. I want to automate this process so that I don't have to ...
3
votes
2answers
123 views

Process in user mode switch to kernel mode. Then the process will have root privileges?

According to http://www.linfo.org/kernel_mode.html in paragraph 7: When a user process runs a portion of the kernel code via a system call, the process temporarily becomes a kernel process and is ...
54
votes
3answers
3k views

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?
8
votes
3answers
2k views

How should I configure grub for booting linux kernel from a USB hard drive?

I have a laptop hard drive in an external enclosure which I use as a large pendrive. For an added twist, I have installed Linux on it, so I can boot any machine with my distribution of choice (e.g. ...
8
votes
4answers
1k views

GRUB on USB Drive — adding OSes

Some Background: Coming from a largely Windows background (though I'm familiar with Ubuntu, etc.) and using a Windows 7 machine to complete this task Have gotten GRUB installed successfully to the ...
2
votes
1answer
577 views

modules make: *** /lib/modules/3.7-trunk-amd64/build: No such file or directory

I need to install Kali Linux updates without Internet access on my laptop. I think I need to do this because I'm trying to install the WiFi driver but I get an error when I try to make: make ...
1
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0answers
25 views

How to correctly set kernel command parameter for sdboot

Thease are the kernel command line parameter Kernel command line (user set) root=/dev/mmcblk0p2 rw rootwait console=ttyPS0,115200 I am trying to run linux from sd card, and the file ...
3
votes
1answer
214 views

What is the relationship between root and kernel? [closed]

Based on part of the first answer of this questions: read from a file (the kernel must check that the permissions allow you to read from said file, and then the kernel carries out the actual ...
3
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1answer
48 views

Result from kernel returned to what process?

When a process requires actions that require kernel mode, it uses a system call. So, how are the results returned to the process?
5
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0answers
73 views

Is my understanding of kernels correct? [closed]

System: Application OS: Scheduler, VMM, IPC, FS Drivers, dispatchers, VFS The above would be a monolithic kernel. In a monolithic kernel all core OS functions are separate from user space. Functions ...
4
votes
4answers
3k views

Cannot create “Hello World” module (and NVIDIA, and VirtualBox)

First off, the details. BEFORE: kernel: 3.2.0-2-amd64, nvidia driver: 295.59 AFTER: kernel: 3.2.0-3-amd64, nvidia driver: 302.17-3 My Debian wheezy is kept recent at all times. Actually, doing ...
5
votes
1answer
288 views

Virtual kernel memory layout: negative values [closed]

i'm porting drivers for omap3-board to 3.5 kernel. When I start board I see it: Memory: 256MB = 256MB total Memory: 253564k/253564k available, 8580k reserved, 3226106074K highmem Virtual kernel ...
0
votes
2answers
916 views

critical section for linux

In linux or a library for linux, is there an equivalent to critical section in win32? I am aware of Mutex, but it is not the same as critical section since a critical section uses user-mode spinlock ...
0
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0answers
16 views

Does ksplice work with updates from repos?

If there is a kernel update from an upstream repository (such as debian or centos) does ksplice work with those updates? If not, how does one update the kernel without a reboot and without paying ...
7
votes
3answers
406 views

What defines the maximum size for a command single argument?

I was under the impression that the maximum length of a single argument was not the problem here so much as the total size of the overall argument array plus the size of the environment, which is ...
1
vote
0answers
455 views

Linux thin station

I have this pc that I just installed and set it up as Linux thin station. I did all the formatting procedures and copying of image to the HD. When I boot it up, I get these, which I think are driver ...
3
votes
1answer
182 views

What is the “kernel build”, and where do I get it?

I am trying to compile OpenOnload from Solarflare for my nic on a server that I'm building. It is saying something about not having a kernel build. root@server:/usr/src/openonload-201310-u2# ...
1
vote
1answer
53 views

Linux Web Kiosk [duplicate]

Hi I'm having a idea of develop a light weight Linux kernel which will boot and open a web browser in full screen and request data from pre define URL. Can any one give me some guides on this please. ...
16
votes
3answers
662 views

What are the responsibilities of each Pseudo-Terminal (PTY) component (software, master side, slave side)?

I am trying to figure out how a tty works1 (the work-flow and responsibilities of each elements). I have read several interesting articles about it, but there are still some blurry areas. This is ...
2
votes
0answers
205 views

Wireless constantly reconnecting on Ideapad running Arch

I just bought a new laptop, a Lenovo IdeaPad U330 touch, and after some struggle (with the Secure Boot stupidity) I have managed to install Arch Linux. I have configured my system, installed all the ...
4
votes
2answers
121 views

How do you get hardware info and select drivers to be kept in a kernel compiled from source?

I would like to create a minimal kernel for a web server. When you compile a kernel from source how do you get hardware info and then know what drivers need to be kept in the kernel so the rest can ...
4
votes
1answer
168 views

How are Linux kernel compile config's determined?

I am compiling my first Kernel (3.5 rc1) from source through menuconfig. Certain configuration options are pre-set. Who / what determines if they are pre-set? Does the make menuconfig somehow ...
1
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2answers
803 views

Automatic kernel configuration tool

Is there any developed automatic linux kernel configuration tool? I have found a method of make localmodconfig, but it is certainly very limited. I have searched the web but unfortunately have not ...
0
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1answer
133 views

Starting Bootlog daemon: bootlogd

Whenever I run linux on many ARM based systems, I see a message like this: Starting Bootlog daemon: bootlogd. As can be seen from the log messages below, it takes some finite time, close to 0.5 ...
1
vote
1answer
38 views

Different Kernel in /boot and the kernel built tree [closed]

I discovered after a binary comparision that my old kernel in /boot was different from the kernel that I had built and kept backed up in the kernel source tree. A while ago I also had a few ...
7
votes
2answers
701 views

How exactly does printk work internally?

I know printf needs help from the OS to do its job. I also know printf does not work in the Linux source code as there is no library. And so we have printk for debugging. How does printk work ...
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0answers
103 views

Looking for a list of modules that are used during boot sequence

I'd like to use deferred init calls. This function allows to load modules in userland, that should actually be loaded during the boot sequence. Just for testing I'd like to modularize as many entries ...
-1
votes
1answer
38 views

Linking option while installing Linux [closed]

I have installed Linux kernel from source. The way I do this is that I first do make menuconfig and then make inside the root directory of the source code. As a result of this I get a an ...
2
votes
1answer
136 views

Where in the linux kernel sources can I find a list of the different keyboard scancodes?

I was looking for a list of keyboard scancodes in the linux kernel sources, but I did not find anything. Does someone know where to find these? Especially the USB scancodes would be interesting.
1
vote
1answer
623 views

Setting up Intel Giga PHY I217V on Debian 2.6.32 kernel

Trying to getting the Intel integrated network card driver (Giga PHY Intel I217V) working on Debian (kernel 2.6.32) but I'm having issues. I've downloaded the driver from the Intel website and ...
3
votes
2answers
256 views

How does a bootloader and kernel interact after the kernel is loaded in memory?

I'm a little bit confused about the role of bootloader and its interaction with kernel, especially when talking wrt ARM Llnux. Once the Kernel is loaded into RAM, is there any job left for the ...
5
votes
1answer
2k views

Writing /dev/random to file?

If you ran the following, what would happen? cat /dev/random > ~/randomFile # don't run Would it be written until the drive runs out of space, or would the system see a problem with this and ...
3
votes
2answers
878 views

BSD Kernel Vs. Linux kernel? [closed]

I wanted to know in technical terms; what is the difference between BSD Kernel and Linux Kernel. In Linux, we can download the source kernel then patch it and make and make modules it. Even we have ...
12
votes
3answers
2k views

Why there are many BSD systems but only one Linux kernel?

Why there are many BSD systems but only one Linux kernel? I wonder why BSD was forked many times, but no such thing with Linux.
2
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1answer
55 views

How does the kernel know which file descriptor to write data to after fork() in a concurrent server?

Basic concurrent client/server architecture: There's a main loop listening for requests on a port (for example 3000), after accepting the connection the server spawns a child process that ends up ...
4
votes
1answer
98 views

How to relate a kernel config setting to the source files?

Here is an example that will explain better: I have a selected the audio driver from the picture and i would like to browse through its source. How do i get to the path of the source files from ...
3
votes
2answers
156 views

Using multiple layer of kernel modules for interfacing a hardware device?

I am trying to get a conceptual understanding of the purposes the kernel modules can have. The motivation for this question was a realization that interface to an actual hardware goes through multiple ...
0
votes
1answer
424 views

How can I install perf 3.4.25?

By installing perf using sudo apt-get install linux-tools-common sudo apt-get install linux-tools-3.2.0.23 gave me perf version 3.2.14 How can I install perf 3.4.25? Is it related to kernel ...
2
votes
1answer
466 views

How to get ondemand governor on fedora

In Ubuntu 13.10 on my (Dual Core i5 Lenovo G570) laptop, I recently discovered the wonders of indicator-cpufreq, so I can extend my battery life dramatically by setting it to 'ondemand' or 'powersave' ...
1
vote
0answers
175 views

How do I fix this boot-up error (attempt to read or write outside of partition)? [closed]

I just installed a version of ubuntu linux that I got from here, http://www.bauer-power.net/2013/06/bauer-puntu-1304-is-alive-download-it.html using vmware workstation. I have installed it before ...
33
votes
4answers
45k views

How to reload udev rules without reboot?

How should one reload udev rules, so that newly created one can function? I'm running Arch Linux, and I don't have a udevstart command here. Also checked /etc/rc.d, no udev service there.
1
vote
2answers
517 views

“select” vs “depends” in kernel Kconfig

What are the differences in dependencies between select and depends on in the kernels Kconfig files? config FB_CIRRUS tristate "Cirrus Logic support" depends on FB && (ZORRO || PCI) select ...
0
votes
1answer
65 views

How can I replace the default kernel with an earlier kernel?

I am working on petalinux, Linux for xilinx FPGAs. The source code is here This Linux is having 3.x kernel, and I have been asked to change the kernel to some earlier release version. What are the ...
3
votes
3answers
940 views

Self-built kernel: failed to mount /dev: No such device

I am trying to install a Linux kernel (3.8.1) from source in a Fedora distribution. The kernel is a vanilla one. I follow the kernel's build instructions closely that is: make menuconfig make sudo ...
1
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0answers
1k views

How to get back from “testing” to “stable” - Kernel downgrade

currently I am having lot's of fun with apt-get - and the bad thing is, it was my own fault. I had enabled the testing packages in /etc/apt/sources.list to install a certain package. And I told my ...
2
votes
2answers
166 views

How to measure PCI-Express bus usage?

I'm looking for a way to find out if PCIe bus is the bottleneck or not. It's not a problem to measure how much bytes was transferred through any particular NIC: Is there a way to find how much ...
4
votes
3answers
491 views

What distribution still supports the 2.6.x kernel?

I'm trying to use a Khepera III robot. The documentation says I need a Linux OS with kernel 2.6.x. An Ubuntu 8 image was provided at the website. When I created a virtual machine with that image, I ...