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

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2answers
565 views

busybox initramfs loop mount

I'm trying to loop mount my root filesystem (a loop file) within a busybox initramfs. I try to run the command: mount /rootfs.raw /root ... which works on my Ubuntu laptop, however, I simply get ...
8
votes
2answers
1k views

Kernel Mode Setting vs. Framebuffer?

With KMS, the graphics drivers are moved into the kernel. Since the framebuffer was already in the kernel, I wouldn't expect this to affect framebuffer operation. Yet, I read that KMS supercedes the ...
5
votes
2answers
584 views

What is the need of the struct thread_info in locating struct task_struct?

While reading through the Linux Device Drivers, I could understand that the Process Descriptor (of type struct task_struct) has all the info regarding a particular task. The process descriptors are ...
3
votes
1answer
436 views

Kernel booting stops right after “Uncompressing Linux…”

I'm trying to bring up an ARM-based board. I've got U-Boot working but can't seem to get the kernel to load. Most of the time it only goes as far as: Starting kernel ... Uncompressing Linux... A ...
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vote
1answer
194 views

Upgrading kernel 2.6.18 to 2.6.32 on CentOS 5.10

I've been looking on Google for 4 hours and I can't find a solution to my problem. I have a computer running CentOS 5.10 using Kernel 2.6.18-371.9.1.el5 and I would like to upgrade my kernel to ...
2
votes
1answer
768 views

Running make with vermagic kernel string with parentheses causes /bin/sh syntax error

I am on Ubuntu Server 12.04 x86_64 and I need to build Android CyanogenMod 7.2 kernel module. My phone has custom ROM and a patched kernel: adb shell cat /proc/version yields Linux version ...
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1answer
25 views

The meaning of Linux Kernel bug output

I have a quick, (maybe naive),question about Linux kernel's output. When I issue a command, the system (Ubuntu 12.04) freezes, the serial port output of this system is as follows: [ 373.805067] BUG: ...
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1answer
103 views

Debian + Linux kernel 3.12.22: “Kernel module loader” option is not available

The Debian guide for compiling a kernel says: Do not forget to select “Kernel module loader” in “Loadable module support” (it is not selected by default). If not included, your Debian installation ...
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1answer
40 views

Common code for kernel and userspace [closed]

I'm working on a linux project. I want to have some code (to be specific, a struct) and a header file (my own implementation) common to both the kernel and the userspace. Can someone tell me how to ...
0
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1answer
30 views

Debian: GPG cannot fetch Linux Kernel key

I am in the process of recompiling the kernel on Debian. Following the instructions on kernel.org, the first step is to verify the signature. But GPG complains that it cannot find the public key: # ...
2
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0answers
51 views

kernel build: why does 'make install' complain about missing modules?

I'm building a 3.2.x kernel on a RedHat Enterpise system. During 'make install' it takes a very long time and is complaining : ERROR: modinfo: could not find module xxx I assume its probing ...
2
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1answer
33 views

Automatized kernel upgrade

I am writing a BASH script that automatically configures, builds and installs the most recent kernel image. The generated kernel should include the grsecurity patchset. It would use the previous ...
24
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7answers
1k views

What's the difference of the Userland vs the Kernel?

I am trying to understand exactly what is userland? everyone that I ask says: "Anything that is not kernel". but it is not tangible for me. When I am reading that kernel can run that driver on the ...
3
votes
1answer
31 views

Open Character Device without creating a Device Node

I'm having an issue where a 3rd party application is opening a device node it shouldn't. I wrote a SPI Slave device driver that does some processing of messages. When the driver loads its in ...
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vote
0answers
41 views

What does this “general protection fault” in my console mean, and how do I interpret it?

I had a couple of consoles open for other work and when I came back to them they both contained the following: Message from syslogd@Stacey-Windows at Jun 19 09:43:28 ... kernel:[ 4375.127165] ...
2
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2answers
45 views

Debian: get package name for installed file

I'm connected via SSH to a PC running Linux kernel 3.11.1: root@alix:~# uname -r 3.11.1 how can I find out which package installed this specific file or kernel version respectively? I tried ...
3
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0answers
390 views

After installing a new Kernel in Ubuntu 14.04, rebooting takes me to busybox initramfs. How do I mount a filesystem after that?

I have a virtual machine with Ubuntu 14.04 in it. I recently built and installed linux-3.14.5 kernel on it, and tried to boot into it, but it drops me to BusyBox v1.21.1 built-in shell. Here's what I ...
16
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5answers
841 views

Where does uname get its information from?

Where does uname really get its information from? I figure this is something that should be straightforward. Unfortunately, I can't find any header containing just that information. Say someone ...
0
votes
1answer
1k 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 ...
9
votes
5answers
1k views

What is meant by “a system call” if not the implementation in the programing language?

I would like to understand the term "system call". I am familiar that system calls are used to get kernel services from a userspace application. The part i need clarification with is the difference ...
8
votes
5answers
3k views

Benefit of kernel module compiled inside kernel?

What's the benefit of compiling kernel modules into the kernel (instead of as loadable modules)?
5
votes
3answers
2k views

ACPI problem with recent kernels

In recent versions of popular Linux distributions (Ubuntu, Fedora, Mint, Debian) I always have to put acpi=off into the kernel parameter list before I want to boot the computer. This happens to both ...
3
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1answer
75 views

When is swap triggered or how to calculate swap_tendency?

I'm trying to use Redis for production services and trying to avoiding swapping, which is bad for performance. I had learn that swap is triggered by swap_tendency which is depending on ...
0
votes
1answer
47 views

How to verify that my uImage is good?

I had a zImage file and I used mkimage tool to convert it into a uImage format. When I am booting this file, it is not been found by u-boot: Wrong Image Format for bootm command ERROR: can't get ...
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vote
1answer
63 views

Booting failing in different Debian and Debian derivated distros?

I've tried Ubuntu, Linux Mint and Debian, even though all have worked great for me I'm keeping with Ubuntu, I tested 12.04, 12.10 and even 13.04. The 12.04 LTS is the one I work with. There's one ...
2
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1answer
115 views

Realtek RTS5209 PCI-E Card Reader only work if card is inserted before boot

Hardware Info Laptop Model: Sony Vaio Pro 13 Problematic Hardware: Bulti-in Realtek Semiconductor Co., Ltd. RTS5209 PCI Express Card Reader Problem description Here is the problem, if I boot with ...
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0answers
28 views

Do kernel threads seem to interfere with full tickless mode?

I'm trying to disable local timer interrupts for low latency. I have full tickless mode enabled in the kernel config and I have the boot parameter nohz_full set for the cores in question. However ...
4
votes
1answer
57 views

Find out if CPU supports dynamic speed setting

I need to find out in my script if a (potentially legacy) CPU supports dynamic speed setting, and eventually get value of maximum and current speed. What makes it more complicated is that I need to ...
2
votes
0answers
51 views

Kernel crash on Fedora distribution but no sign of kernel panic

I am running kernel 3.14.4 on Fedora 18. I am experimenting with a kernel module I am making. The module has a bug (at least one) and crashes the kernel. Sometimes I see a stack trace on my frozen ...
8
votes
4answers
2k views

IDE for large, multi-language projects (ie linux kernel)

I know the "which IDE do you guys use" question has been asked a million times. But I've never seen it asked in this context. What are some suggestions for an IDE when working on huge projects that ...
3
votes
1answer
2k views

vmlinuz and initrd not found after building the kernel?

After configuring and building the kernel using make, why don't I have vmlinuz-<version>-default.img and initrd-<version>.img, but only got a huge vmlinux binary (~150MB)?
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0answers
66 views

Updating kernel on a Chromebook to prep for Chrubuntu

Pretty simple question: I have read that by setting my Chromebook to the dev channel, it will install a later kernel. Currently it's 3.4.0, and it'd install 3.8.0 (64-bit, no less). However, after ...
0
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1answer
74 views

Kernel 3.14.1 compilation errors

I installed the kernel 3.14.1 and there seem to be no issues. uname -r 3.14.1-031401-generic However, when I try to go to the folder and try to do a make it fails. I see that multiple files are ...
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vote
2answers
43 views

How to find out the bad block table offset and how to change it in u-Boot

I am facing a similar problem as this: Kernel does not recognize nand bad blocks marked by u-boot I'm using a friendlyARM micro2440 board that contains the s3c2440 ARM processor. u-Boot has found ...
2
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1answer
37 views

kernel event listener

I wonder if there is something similar to an event listener in UNIX that a program can subscribe to? Specifically I want to know: Start and end times of a user session Start and end of the ...
-1
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1answer
69 views

MIC not working due to USB bandwidth

Using debian and centos, i get the same error when plugging my USB mic in. In Windows (xp thru 8.1) it works fine. [ 304.237543] usb 2-1.6.2: USB disconnect, device number 6 [ 305.220785] usb ...
4
votes
1answer
51 views

What causes /proc/<pid>/* resources to become owned by root, despite the procs being launched as a normal user?

I've noticed that some procs, such as bash, have their entire /proc/<pid>/ resources readable by the user who created that proc. However other procs, such as chrome or gnome-keyring-daemon, have ...
1
vote
2answers
317 views

Kernel freezes on loading ramdisk. How to find out what's wrong?

I'm using an Ubuntu Server (13.04) Minimal installation (with the Xubuntu Metapackage as a desktop environment, if that matters) on x86_64 on my Samsung notebook. I'm currently forced to use the ...
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2answers
90 views

How do I enable kernel option MMC_UNSAFE_RESUME

I am trying sleep and wake up my Kobo Mini ebook reader manually by using the command rtcwake. The reader is using busybox. cat /proc/version gives me this output: Linux version 2.6.35.3-850-gbc67621+ ...
1
vote
0answers
24 views

Adding IPVS to the kernel

I am trying to setup keepalived on a pair of VPS load balancer servers. I have hit the road block of IPVS not being included with the kernal. IPVS: Can't initialize ipvs: Protocol not available I ...
2
votes
0answers
19 views

Intel Xeon stuck at 800mhz CPU Freq on RHEL 6.5 [duplicate]

Currently running into a headache trying to figure out why my CPU speed is stuck as such a low frequency. After doing some research, I found that cpuspeedutil does actually control the state of the ...
0
votes
2answers
90 views

Porting jvm into the kernel space?

Currently I am playing with the idea of a jvm running in the kernel space, as a (maybe linux) kernel module. I see a lot of advantage of the idea. Of course the biggest advantage of a such system ...
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vote
0answers
34 views

Get log from kernel while loading

There is a arm/omap2-based device without ethernet, UART ports. It has usb connection with host, numeric keyaboard, LCD display. There is working U-Boot and kernel images for this. I'm trying to ...
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vote
3answers
849 views

How to install kernel on debian with no internet connection

I'm trying to install a newer kernel version on my Debian (squeeze) machine as I need it to get my wireless card working. I have Debian on one partition of my hard drive, Fedora on the other. I'm ...
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0answers
41 views

How to check and set “rhash_entries” parameter?

I'm reading this article, and it says: rhash_entries is the size of the hash table. If you don't specify it on the kernel command line, it is computed dynamically based on the memory available on ...
3
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1answer
132 views

Library routines in linux kernel

In the linux kernel, there is a section "Library routines" with a snippet shown below: Library routines ---> <M> CRC-CCITT functions <M> CRC ITU-T V.41 functions <M> CRC7 ...
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0answers
59 views

ftdi_sio not pre-installed

I have recently recompiled my Ubuntu's kernel to Linus' most recent one. After rebooting, I tried to connect my computer to a development board via an FTDI FT232 USB-to-Serial converter. It used to ...
0
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0answers
46 views

How to set sctp_nodelay to enable piggybacking while replying back

Problem: We are hosting a telecom application that receives traffic from the network at > 500 TPS. The packets are piggybacked so each sctp packet contains multiple application layer packets lets say ...
1
vote
1answer
81 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 ...
2
votes
2answers
234 views

Where does make defconfig get its configuration in OpenWrt?

I am compiling an image for wifi devices using OpenWrt. Following the instruction I copy a simple .config file to TOP-DIR. CONFIG_TARGET_ar71xx=y CONFIG_TARGET_ar71xx_generic=y ...