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

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283 views

Does linux modules/drivers belong to kernal space or user space

Some articles say that modules/drivers belong to kernel space as it take part in forming the kernel; (reference: http://www.freesoftwaremagazine.com/articles/drivers_linux) While others say that ...
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1answer
324 views

ixgbe: increase rx performance

I have an Intel 82598EB 10GBE NIC. I need to receive traffic without packet loss. Data rate is 4-5 Gbps, packet size is 1500-9600 bytes. I had already configured smb and irq affinity. I also tried ...
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1answer
177 views

How to measure the clock pulse of my computer manually?

My PC has two processors, and I know that each one runs at 1.86 GHz. I have just read about clock cycles and I only have a (very) rough understanding, so I apologize beforehand if my question is so ...
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2answers
10k views

what is pts/0 and (:0.0) in linux by type who am i

When I type the command: [root@degeneration Desktop]# who am i root pts/0 2013-04-12 15:08 (:0.0) What is pts/0 and what is meant by (:0.0)?
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2answers
41 views

can't update with this error messg

I got this message: not enough free disk space.... The upgrade needs a total of 31.8 M free space on disk '/boot'. Please free at least an additional 31.8 M of disk space on '/boot'. Empty ...
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1answer
333 views

Can entropy consumption at program start be prevented?

I use Knoppix (or other Live CDs/DVDs) as a secure environment for creating valuable crypto keys. Unfortunately entropy is a limited resource in such environments. I just noticed that each program ...
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2answers
1k views

What are “kernel data structures”?

While reading about the Linux kernel I came across the notion of kernel data structures. I tried to find more information via Google, but couldn't find anything. What are kernel data structures? ...
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1answer
448 views

Would someone please explain lspci -vv output?

I have the following output from running lspci -vv -s 00:00 on my single board computer running Linux. 07:05.0 RAID bus controller: Adaptec AAC-RAID (Rocket) (rev 03) Subsystem: Adaptec ASR-2230S + ...
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1answer
801 views

Only output errors / warnings when compile kernel?

When you compile kernel you normally see lines like CC XX.o or LD XX So, can I skip these messages? Only output errors or warnings generated by gcc
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2answers
235 views

Locate occasional CPU kernel hog

I have a 2.6.35 PREEMPT kernel running on moderate-speed ARMv7 processor. About once every 100 - 125s, something causes the kernel to fail to process some audio-related drivers sufficiently quickly to ...
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2answers
2k views

Why does modinfo say “could not find module”, yet lsmod claims the module is loaded?

According to the man page of lsmod the command shows “what kernel modules are currently loaded”. I wrote a script that uses modinfo to show what kernel object (.ko) files are actually in use: ...
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0answers
762 views

Unable to install the selected kernel

I have problem with my DVD drive. It's corrupted and when I'm trying to install Ubuntu it stucks (even with the miniISO) I was able to successfully start the OS from system rescue CD. I'd like to ...
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1answer
314 views

How to troubleshoot high kernel time (high network usage; high interrupts)

I've noticed that I have high kernel time when doing a lot of network traffic in Linux. I also noticed that 45% of my CPU is spent doing interrupts. How can I further troubleshoot this?
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1answer
133 views

Force Debian kernel version

I need Debian with kernel 2.6.34.8 Is there any way to force Debian with it? I don't want to install and then compile version I need.
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2answers
182 views

How is the kernel loaded?

I am trying to understand the Linux boot process, and after reading quite some amount of documentation there is one point that I still can't seem to understand. So the basicis is BIOS -> Grub MBR -> ...
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0answers
26 views

Figure out which distro I'm using with Zsh script [duplicate]

I'm making a script that installs some basic needs of mine on my newly installed Linux. However depending on the Linux distro the contents and commands would be different. In Arch Linux I would use ...
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1answer
138 views

How to create a debian 3.x kernel rootfs on a 2.x host

I'm trying to build a rootfs for an embedded A10 board. This will be matched up against 3.0.62+ modules and a corresponding vmlinux image. I've been trying for a few days to get a rootfs set up for ...
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2answers
1k views

How do I determine ZCACHE works on my box?

I have an Marwell Kirkwood ARM-based NAS server Zyxel NSA 310. I compiled my own 3.8 kernel and enabled ZCACHE, but I still see 256 MB of RAM. I am not sure if GNU free utility should show extra ...
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1answer
307 views

Where to start profiling Linux kernel?

What are the standard and conventional ways of profiling the Linux kernel? I know there is perf tool but is there anything else?
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1answer
208 views

What information exactly is in the access control bits of a page table?

I'm currently learning for an exam in operating systems. This includes learning some basics about page tables, which lead me to the question Why using hierarchical page tables? which mentions that ...
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1answer
82 views

Relation between the kernel version and OS version

I am running a Ubuntu of version 12.04. Can I use a kernel of version of version 2.4 on it?
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2answers
44 views

Kernel compilation of version 2.4 on a system running 3.2.0

My current kernel version on with my OS running on is 3.2.0. Can I compile a kernel of version 2.4.0 on it? Is there any perfect kernel documentation available? (As I see different ways of compiling ...
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2answers
648 views

kernel module function call

I write a kernel module which has initialize and end function. I want one more function and want to call it from the user space process at any time i want. Is it applicable ? If so, how ? I am ...
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5answers
216 views

How to know what to enable in the kernel?

I'm a gentoo user. When compiling the kernel there are a lot of options which one may enable depending on one's hardware. My question is how to know what to enable/disable, I'm aware of the hardware ...
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0answers
169 views

Pinnacle TV tuner card, readreg error, dvb_register failed, cx8802 probe failed, firmware never loads

I'm trying to make this card work in a touch screen kiosk running Ubuntu 10.04, kernel 2.6.32-45-generic This card seems to use the s5h1411 chip instead of the s5h1409 the modules are expecting. I've ...
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2answers
247 views

Writing a Linux file system for NFS

I want to write my own custom file system in Linux. Can I share it over standard NFS without making any changes to the local NFS server? If so what VFS APIs are required to be implemented by my file ...
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0answers
129 views

Is there a way to undo VGA adapter modesetting in Linux

I'm looking for a way to reset the graphics adapter to textmode after it has been set to some sort of graphical mode by the kernel on bootup, and possibly used by an X server. Is there any code to do ...
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1answer
91 views

How to give an ordinary user privileged access to a particular syscall in FreeBSD?

I want to give an ordinary user the ability to fchown() files arbitrarily (as if they were the superuser) on FreeBSD. Generally speaking, is there a right way to change the privilege-checking of a ...
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0answers
178 views

pptp differs between 3.7 and 3.8 linux kernel milestone with 3.2.0-4 milestone

Unfortunately, current kernel of debian has problem with my hardware: 3.2.0-4-686-pae , and when i compile one of 3.7.x milestone or 3.8.1 itself , my problem is solved. But my problem with new ...
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2answers
223 views

Linux kernel development for multi core architecture

I am working on a project adapting system software like the Linux kernel. I read one paper titled "Experience on Comparison of Operating Systems Scalability on the Multi-core Architecture" that tells ...
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3answers
686 views

swap partition and its laws

I remember for choice of swap partition, we should use (swap > 2xRAM) at least.Of course it deprecated , because max of computer's ram is very high. kernel support it. My question: i remember each ...
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3answers
11k views

How to cause kernel panic with a single command?

Is it possible to cause a kernel panic with a single command line? What would be the most straightforward such command for a sudoing user and what would it be for a regular user, if any? Scenarios ...
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3answers
154 views

Control how linux deletes files

What exactly happens when an application deletes a file? Is there any way to control this behavior? Basically I want to shred instead of rm in all cases, but of course applications do not make calls ...
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1answer
196 views

How does kernel swapping / INT 13h interrupts work?

I'm looking for a way to learn about and understand this technique. Here's what I'm talking about: Slax boots, {does stuff, like copy itself to RAM}, then transitions control to the kernel/file ...
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2answers
1k views

Skip all new device drivers in `make oldconfig` for Linux kernel

When using make oldconfig I usually look at new options briefly in case there's something important/useful. However, on an existing system I couldn't care less about new device drivers for some ...
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1answer
337 views

Kernel headers for VMware tools

I tried to compile VMware tools on my server. I compiled the kernel myself, I didn't use RPM. As VMware tools needs the kernel header files, I executed the following command in my kernel folder ...
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2answers
722 views

Kernel/grub : how override root parameter inside initrd script

I have an old kernel ( 2.4.37.9 ) and I want to override or substitute the root=XXXXX parameter to send to the kernel inside the initrd script. I already made some attempt to do that but it seems ...
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1answer
308 views

Using a custom name for root device in GRUB

I'm working on old distro ( slackware 8.1 ) using a kernel 2.4.37.9 and I have the following problem. I want to use a custom name for boot device, say for example /dev/root1, which can replace the ...
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3answers
1k views

Disadvantages of linux kernel module?

I am trying to understand the disadvantages of using Linux kernel modules. I understand the benefits of using them: the ability to dynamically insert code into a running system without having to ...
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0answers
435 views

Lowering kernel timer interrupt frequency

When I run my Virtual Machine with Gentoo as guest, I have found that there is considerable overhead coming from tick_periodic function.( this is the function which runs on every timer interrupt).This ...
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2answers
495 views

If I redirect logs using rsyslog, will dmesg be affected?

I am trying to get some logging in place and am trying to troubleshoot it and this question became relevant. I use rsyslog config files to redirect some of my logging. (Will use iptables logging ...
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1answer
250 views

Initrd : Were can I found the code for real-root-dev

I'm trying to customize my initrd on kernel 2.4. At some point, inside the file linuxrc, I have the opportunity to set my root device setting the /proc/sys/kernel/real-root-dev variable The example ...
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3answers
567 views

How to list all hardware supported by kernel

I want to see all hardware supported by the kernel in use. For example, if I have the 3.8.x.x version of the Linux kernel, how will I know what hardware is supported there. Tools like lspci, lshw, ...
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4answers
47k views

What is the difference between reboot , init 6 and shutdown -r now?

I just want to know difference between in reboot init 6 shutdown -r now and which is the safest and the best?
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0answers
1k views

Intel Core i3/i5/i7 Sandy Bridge CPU throttling

Intel Sandy-Bridge family i5 Core CPU, running Linux kernel 3.2 (Debian Squeeze/Wheezy), under heavy computation load, does not react to to cpufreq-set -g powersave (using acpi_cpufreq module). It is ...
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1answer
129 views

What is the source of truth for currently active tty/pts connections?

I'm looking for a simple way to determine the number of currently logged in users, using only the filesystem and basic bash functions (instead of using binaries). The uptime binary appears to be ...
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2answers
286 views

TLB cache flusing when a page is swapped out

I recently heard that Linux simply flushes the TLB cache when the corresponding data in that physical address is swapped out, resulting in underutilization of the TLB. I don't know whether all OSes do ...
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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 ...
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1answer
44 views

USB_HID is not working

How do I get a usb keyboard to work? I have already selected and compiled the USB HID transport layer and I don't know what else to do.
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1answer
672 views

How to avoid overflowing the kernel printk ring buffer?

I'm trying to debug a linux driver and a particular piece of code is behaving very strangely. In order to see what's going on I've filled the code with printk statements so I can see exactly what the ...