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

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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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215 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 ...
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What is the minimum round robin scheduing interval supported by Linux?

For some reason, I want to have 10 processes share the same CPU core by affinity. As you know, to achieve CPU sharing between processes, we can exploit the Linux round robin (RR) scheduling policy. ...
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121 views

Is this a so-called “Hybrid” Mac Partition table, and how can I mount this in Linux?

I would like to better understand what is on this hard disk, and how I can mount it into Linux (specifically Debian GNU/Linux, Stable): It was created on a Powerbook g4 "alu book" with the default ...
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1answer
63 views

iproute command: ip -6 rule show nothing even with kernel option IPV6_MULTIPLE_TABLES=y

I want to enable my linux 3.2.4 to have ipv6 multi-routing table functionality. I enable IPV6_MULTIPLE_TABLES when make menuconfig and rebuild kernel.(Also with ip advanced routing and ip multi table) ...
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20 views

debug a program causing a crash gnome

I've found a bug when running from a browser to a page like the picture below I run into And as you can see I have no choice but to logout The ability to set logging on the switch I used gdb ...
0
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1answer
120 views

use drivers from old kernel in new kernel

I am using newest Raspbian but I found out stk1160 drivers are not working properly. But in older raspbian it works ok. So I would like to move drivers from older Raspbian to newer Raspbian. How can I ...
3
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1answer
717 views

How to debug random reboots, with no kernel panic, of an embedded system?

I have two aValue RPC-10W1 embedded systems that reboots by themselves after 1-2 hours. Facts: The board will reboot within a time span of 1 to 2½ hours. The issue is present on two identical ...
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67 views

How to take the log of the patches we applied?

So here's my question I recently downloaded the linux kernel patch 3.4.101 and i applied this patch directly to the base 3.4.0 with this command: $ cd /kernel source directory $ gzip -cd ../path to ...
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53 views

Possibile sources of 5us-20us latency gap when sending long block of of serial data to tty device?

I have a trivial C program that just sends a large block of data out the serial port at a fast baud rate. When looking at the bits actually coming out of the port, I see that there is a almost always ...
3
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1answer
283 views

Spawn multiple dirty page flusher threads per device

In earlier 2.6.X kernels, pdflush was used and it would spawn more pdflush threads if all current pdflush threads were busy for a second (read from The Linux Page Cache and pdflush). Since the ...
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77 views

Is a page with “PROT_NONE bit set” eligible for swapping?

From the following link: Page Table Management - kernel.org, I understood that the bits PROT_NONE and PRESENT can be used to let the OS know that a page is protected but is resident in memory. I am ...
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114 views

How does the kernel store the virtual memory area?

I am trying to understand do_page_fault in fault.c (x86 architecture). I came across the method access_error where we compare the error code to the vm flags. As per my understanding, we are checking ...
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2answers
71 views

Using Linux kernel config file from version to version

I have currently Linux Kernel 2.6, which works for my hardware. Now I want to compile Linux kernel 3.2 for the same hardware. Can I use the same .config of 2.6 directly for v3.2? Is there any ...
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439 views

Linux kernel manual build: resulting binary is 10 times larger than precompiled binaries

I'm using Linux Mint 13 MATE 32bit, I'm trying to build the kernel (primarily for experience and for fun). For now, I like to build it with the same configuration as precompiled kernel, so firstly ...
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1answer
55 views

How do you patch a kernel? [duplicate]

I got diff text from lkml how do I patch it into a kernel source? I am very new to compiling kernels, and I couldn't find decent sources online I am using debian if it is relevant
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773 views

installing grub and a working kernel over an old and broken debian system

I have an old debian system, which I always have been able to upgrade over the years. I had installed an old kernel, compiled by me from sources. After my last dist-upgrade (using testing ...
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64 views

Questions about kernel releases

Right now there are about 7 (or more) kernels maintained by the Linux Foundation. I was wondering if you could clarify my doubts and answer my questions: Isn't the next kernel's release maintaining ...
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179 views

Loginuid, should be allowed to change or not (mutable or not)?

I am trying to configure the linux kernel. I was confused by Make audit loginuid immutable (AUDIT_LOGINUID_IMMUTABLE) [N/y/?]. The help says: +config AUDIT_LOGINUID_IMMUTABLE + bool "Make ...
5
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2answers
577 views

File handles and filenames

I read this post. Are file descriptors the same as file handle? While trying to configure the linux kernel, it asks open by fhandle syscalls (FHANDLE) [Y/n/?]. Why is this option provided? Does ...
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1answer
65 views

How do I know what decompression algorithms are compiled-in into the linux kernel?

If /proc/config.gz is unavailable, how do I know what decompression algorithms the running kernel is capable of using on a compressed cpio initramfs? Is the gzip algorithm always available, even when ...
3
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1answer
151 views

How do I find out what filesystem drivers are compiled-in into the linux kernel?

On a running linux system, what is a portable (among linux distributions) way to find out what filesystems the current kernel has compiled-in (not through modules) support for? Consider for example ...
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1answer
249 views

Enable BFQ in Fedora

I am running Fedora with the stock kernel and I'd like to enable the BFQ disk I/O scheduler, and ideally BFS. I have built my own kernel and that works, though it is a royal pain dealing with the ...
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3k views

USB set to /dev/sda instead of /dev/sdb

I've been trying to use a kickstart file to guide the Red Hat installer (RHEL6.5) without user intervention. It correctly looks for the kickstart file in /dev/sdb/fs.cfg, but because the USB is ...
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Kernel bisect: when a patch is failing for a reason other than original bisect purpose, what do you do? [closed]

Let's say you're trying to find the cause of a bug between 3.11.0 and 3.12.0. The bug is really difficult to catch, because it may or may not manifest itself over several days of regular workload ...
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aircrack-ng shows negative channel

On many Linux distributions, be it BackTrack, Kali, BackBox, Ubuntu, Mint, etc., whenever I use anything from the aircrack-ng suite my wireless card is shown as channel -1. This problem has been ...
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1answer
96 views

How do I compile source into the kernel?

I want to add and compile my custom application code into my kernel. How should I add my .c and .o files into my kernel 'bin' directory and compile them? I made a hello.c and hello.o file and I want ...
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2k views

In what sense does SATA “talk” SCSI? How much is shared between SCSI and ATA?

This is nothing new to me at least, that SATA actually "talks" SCSI, hence why these SATA devices show up as SCSI devices in Linux. A related question has been asked before, e.g. Why do my SATA ...
6
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1answer
279 views

File backed, locked shared memory and disk interaction

Varnish, a HTTP accelerator, uses a ~80MB file backed SHM log that is mlock()ed into memory. The Varnish docs recommend to store the file on tmpfs to avoid unnecessary disk access. However if the ...
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2answers
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Linux 2.6.36.4, GCC 4.7.2, getting lots of “variable set but not used” warnings

I am trying to compile the Linux kernel 2.6.36.4 on Linux Mint 14 running a 3.5 kernel by default. Using gcc version 4.7.2. Tried googling it, but didn't quite work out. The warning is: warning: ...
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SLES 10 SP4 - how to get specific kernel source?

I want to look at the kernel source for some specific kernel versions on SLES 10 SP4. I don't want to see just the Linux kernel source, but the one SLES is actually running. Suppose I wanted to get ...
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Virtual kernel memory layout in dmesg linux kernel 2.6.31

I'm working on a embedded linux project for ARM architecture, kernel version is 2.6.31.12-rt21. In dmesg, I cannot see the virtual kernel memory layout like this: virtual kernel memory layout: ...
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inotify does not work with linux kernel 3.4.11

I have a Linux running with kernel 3.4.11. I tried to run inotify-tools, but it does not work (in fact it does not detect the file changes). I checked the .config file of Linux kernel and I found ...
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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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262 views

ncurses-devel problems in SuSE Linux Enterprise Desktop 11

Searching on the WEB, I found this tutorial (the only one that has convinced me) for installing a new kernel and I followed the steps provided. But, I got these problems: In the first step I tried ...
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1answer
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kernel config with strange dependancies

I am trying to build the Android Linux kernel from source following this README. The instructions very clearly state: 1.1 Required enabled config options: After building a standard defconfig, ...
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1answer
374 views

How is 32bit Linux virtual memory structured in relation to PCIe Base Address Registers

I'm working on a Linux system (32 bit, 4GB RAM) and found some contradictory information about memory addressing in Linux. Am I right with this: Only virtual memory has the differentiation between ...
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1answer
632 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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211 views

Linux memory usage?

We have 1TB of memory on a server which hosts an SAP application. When the app is running the memory usage shown in top is around 700GB. When the app is stopped the memory usage shown in top comes ...
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Who is responsible for the Linux kernel?

As of today, there are many Linux distributions like Ubuntu, Fedora, Gentoo, Mint, Debian, etc. These distributions update at different cycles. Ubuntu seems to update its kernel weekly or monthly, ...
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174 views

Running assembly program as ring 0

I'm writing an application which reports back readings from CPU temperature sensors, and the fan speed monitor. However, according to the Intel documentation on PECI, the instructions required must be ...
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1answer
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Built the kernel with NFS support but not getting /dev/nfs

I'm trying to build kernel 3.13.9, fetched using apt-get source, and built in a clean debootstrap chroot (both host and chroot being installations of Ubuntu Trusty). My goal is to boot a diskless ...
2
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1answer
111 views

Can 32 bit applications on a 64 bit kernel use all the memory?

I know that the 32-Bit kernel can use PAE to allocate more RAM to applications with PAE (up to 64GB) as such I imagine if I am running 32 bit applications on a 32-bit kernel I can use all of my 24GB ...
2
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1answer
165 views

I/O schedulers for normal harddisks

For me figuring out what is the best choice for I/O in kernel was a challenge. First I learned that it is subjective then it is depend upon the File-System you use. I know you should use No-op for ...
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1answer
102 views

View all disabled or hidden linux kernel options

I am trying to build a 3.12 Linux Kernel and I see some of the options (sub menus) are hidden and their branch (menu entry) is disabled in make menuconfig. [---- instead of being --->] I know ...
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What is equivalent to Mac's purge in Linux?

In Mac I use purge to free up some memory. What is equivalent to it in Linux(Ubuntu Server)? apt-get install purge gave me nothing. If you are no familiar with Mac's purge here is it's man page: ...
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Testing the Success of a Congestion Algorithm

How do you test whether a particular congestion algorithm is working for you? I ask because it's not as if I can easily re-create a representative workload for most algorithms. I'm current looking at ...
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380 views

How do I make strace “decode” AF_NETLINK comminucation like with ioctl?

strace usually "deciphers" ioctls, showing what do they mean, even resolving network interface names and so on. But the same operation performed using AF_NETLINK stays opaque in strace. How to teach ...
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What are the two head.S files in linux source ?

In the linux source there are two different head.S files located at: arch/arm/kernel/head.S arch/arm/boot/compressed/head.S What is the puprpose of each one and what is the order of there execution ...
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What is the purpose of patches of the linux kernel?

For each Linux kernel version, there is a patch file available for download. For instance, linux-3.12.22 has a corresponding patch-3.12.22. What is the purpose of that patch? To always patch the ...