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

learn more… | top users | synonyms

3
votes
3answers
32 views

How do I check the running kernel version?

While troubleshooting a problem with my ethernet card, I've found that the driver I'm currently using may have some issues with old kernel versions. What command can I use to check the kernel version ...
0
votes
0answers
10 views

Compiling FreeBSD on OSX

I currently have the source for the FreeBSD kernel. I want to compile it and create an iso image, on my OSX 10.9 computer. Can this be done? Do I need any other tools?
0
votes
0answers
19 views

4.2 kernel build, missing version.h

I have installed a 4.2 vanilla kernel on Kali Linux 2.0 and prepared the kernel source with make clean prepare I then copied the source to the /usr/src/linux-4.2 directory. And this is symlinked to ...
1
vote
2answers
29 views

On page fault, how does Unix determine if the faulting address is in swap space?

When a page fault occurs for a virtual address for any process how does the linux/unix operating system determine whether that page (of that virtual address) was swapped previously present in memory ...
0
votes
1answer
592 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
0answers
22 views

Is information security less hard in an open source system? [on hold]

In the excellent article Why Information Security is Hard - An Economic Perspective, Ross Anderson poses that: ... you can make the security critical part of the system small enough that the bugs ...
17
votes
4answers
10k views

What is the difference between the following kernel Makefile terms: vmlinux, vmlinuz, vmlinux.bin, zimage & bzimage?

While browsing through the Kernel Makefiles, i found these terms. So i would like to know what is the difference between vmlinux, vmlinuz, vmlinux.bin, zimage & bzimage?
4
votes
2answers
953 views

Benefiting of sched_autogroup_enabled on the desktop

I am running a 2.6.37 kernel with sched_autogroup_enabled set to 1. I am not certain that I am seeing the benefits of this patch since: I am launching my applications from the desktop; applications ...
1
vote
1answer
27 views

How to find out what distros are using particular Linux version?

Given a distribution and its version, I can find which version of kernel it uses, e.g. for Ubuntu they are listed here, and for currently supported versions of Fedora they are here. In general, ...
10
votes
1answer
9k views

How can I mount filesystems with > 4KB block sizes?

I have a 3TB hard disk pulled out of a WD Mybook Live NAS. The partition table is as follows: Model: ATA WDC WD30EZRS-11J (scsi) Disk /dev/sdb: 3001GB Sector size (logical/physical): 512B/4096B ...
1
vote
0answers
31 views

What does raw_spinlock mean? [closed]

I was studying struct raw_spinlock which is in the /usr/src/linux/include/linux/spinlock_types.h was like this: typedef struct raw_spinlock { arch_spinlock_t raw_lock; #ifdef ...
41
votes
2answers
20k views

Kernel inotify watch limit reached

I'm currently facing a problem on a linux box where as root I have commands returning error because inotify watch limit has been reached. # tail -f /var/log/messages [...] tail: cannot watch ...
3
votes
0answers
47 views

ABRT report says “irq 19: nobody cared”, but why?

Every couple weeks, I need to reboot my system. When I do, and enter as root in the terminal, the following message (in some variation) appears: ABRT has detected 3 problem(s). For more info run: ...
1
vote
0answers
10 views

Is there something like “make localmodconfig” that detects *all* your hardware?

I understand that Linux's "localmodconfig" target looks through all your loaded kernel modules and produces a .config file that enables those modules. This is nice, but what about hardware whose ...
0
votes
2answers
43 views

How to create (or modify) Linux distro? [closed]

I've read about this and I think that Linux From Scratch is good, however, I'm confused what part I should begin with. My intention is to modify Linux distro - adding or removing some features and ...
1
vote
2answers
169 views

What is “fs” short for in kernel function “get_fs()”?

There are two Linux kernel functions: get_ds() and get_fs() According to this article, I know ds is short for data segment. However, I cannot guess what "fs" is short for. Any explanations?
1
vote
2answers
75 views

What causes the ata exceptions in my syslog and how to solve them

I have a new system with debian (omv) a SSD hard drive for the OS and a software RAID 6 for the data. I only saw now that I have very regular exceptions in my syslog. I'm worried now, what could ...
0
votes
0answers
19 views

Kernel config for HP Stream 13 (booting from emmc disk)

I'm trying to install gentoo on hp stream 13 device and i am unable to boot up system from the emmc hard drive. Before trying gentoo on this device i have successfully installed debian, which clearly ...
0
votes
0answers
7 views

tRecompile the kernel changing only one option

I've already built a custom kernel based on the mainline 4.1.6. Now I want to disable CONFIG_ACPI_I2C_OPREGION The kernel build doesn't take very short, so I'd like to rebuild only the parts affected ...
50
votes
11answers
4k views

What's the philosophy behind delaying writing data to disk?

In Linux, a finished execution of a command such as cp or dd doesn't mean that the data has been written to the device. One has to, for example, call sync, or invoke the "Safely Remove" or "Eject" ...
1
vote
1answer
15 views

Why is debug_putstr() not being printed during boot?

I'm asking myself why debug_putstr() in arch/x86/boot/compressed/misc.c is not being printed during x86 boot phase, though it is configured to do so with GRUB_CMDLINE_LINUX_DEFAULT="". On other ...
0
votes
1answer
14 views

How can I update the kernel and initrd images in EFI boot loader?

I have successfully installed the EFI boot loader (using ELILO) but I am unsure how to actually keep the kernel images up to date. Can you help me understand the process please? Thanks. ...
0
votes
0answers
17 views

check-config errors on Linux 3.19.0 kernel, configured under Ubuntu 15.04 x86-64

I'm new to configuring Linux kernels, and am receiving the following errors when running config-check: check-config: /tmp/tmp.tnqExc0fHn/CONFIGS/amd64-config.flavour.generic: loading config ...
0
votes
0answers
18 views

scripts/checkpatch.pl: Warning: consider using a completion

I'm currently writing a kernel driver that involves moving large amounts data from userspace to or from a peripheral, via a ring of bounce buffers. The buffer completion callback ups a semaphore, and ...
1
vote
0answers
13 views

Best way to approach HID_MAX_USAGES kernel errors?

This is an issue I have for the second time now: basically, an USB based device reports some wrong numbers for "HID_MAX_USAGES", resulting in the kernel giving an error message and the device not ...
22
votes
5answers
5k 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 ...
2
votes
0answers
9 views

What is “state-object” in cgroups

I am gathering some idea about lxc, kernel name spaces and cgroups. While reading man lxc-cgroup, i find : lxc-cgroup gets or sets the value of a state-object (e.g., 'cpuset.cpus') in the ...
5
votes
3answers
4k views

ulimit & rlimit in Linux, are they the same thing?

I see people use the terms ulimit & rlimit interchangeably, can I say they are referring to the same thing?
0
votes
0answers
18 views

Stack pointer of the interrupt stack

Linux kernel has separate stacks for user mode and kernel mode process and also some special stacks. One of this special stacks is interrupt stack with the size 16 kilobytes placed in the ...
74
votes
13answers
11k views

What is the benefit of compiling your own linux kernel?

What benefit could I see by compiling a Linux kernel myself? Is there some efficiency you could create by customizing it to your hardware?
3
votes
3answers
943 views

Set default kernel in GRUB

How can I pick which kernel GRUB2 should load by default? I recently installed a the linux realtime kernel and now it loads by default. I'd like to load the regular one by default. So far I only ...
0
votes
1answer
25 views

Does MySQL processes run in user or kernel modes?

I try to count IOPS and I/O size with SystemTap script and use MySQL to be workload. I found mysqld doesn't call systemcall but mysqld has read/write on VFS. So, do MySQL processes run in user or ...
0
votes
1answer
39 views

Linux modules take a lot of space [closed]

I'm using the 4.1.2 mainline kernel. The package with image and all modules has 207 MB of installed size. I built a patched 4.1.6 kernel, taking the config from the current kernel and now the drivers ...
0
votes
0answers
82 views

Error while trying to compile/install kernel, 4.1.6 on Ubuntu 15.04

I'm trying kernel compilation in Linux for the first time. I'm using the guide here to learn the basics. I'm able to pull the source code from the git repository, and can compile it. However, I run ...
4
votes
1answer
3k views

Setting up HDMI output from Linux console

I am currently running Debian Wheezy on a HP Microserver N54L with an AMD Radeon 5450 video card. I would like to be able to play audio from the console through the HDMI port of my video card and ...
0
votes
1answer
24 views

how to set i2c bus to soc audio codec

I'm working on an audio codec driver for cs4245 device. It's controlled by i2c. I have 2 hardwares (devel-board), one of the them has the codec attached to i2c-1 and another to i2c-2. The first one is ...
1
vote
3answers
338 views

Log message “Disabling IRQ”: what does it mean?

This message appears in my dropdown terminal at seemingly random times when no processes is running in that terminal: andreas@debianator:~$ Message from syslogd@debianator at Feb 24 18:57:58 ... ...
0
votes
0answers
17 views

X stopped working after a kernel update

My system is a laptop with Ubuntu 14.04, with an Intel CPU and Intel + Nvidia GPU combo. After one automatic kernel update, the GUI stopped working. It shows a blue loading screen with a spinner, up ...
3
votes
2answers
2k views

running kernel on QEMU

I face this message: Failed to execute /initKernel panic - not syncing: no init found. Try passing init=option to kernel. I am using this command line: qemu-system-x86_64 -hda disk.img -kernel ...
27
votes
8answers
3k 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
1k views

Scaling issues of i7 3520M with intel_pstate module on Kernel 3.10.0

Few days ago I updated my openSUSE 12.3 system from Kernel 3.9.8-1.gf3348a8-desktop to 3.10.0-1.g3dcd746-desktop and since then, turbo mode of my i7 3520M is enabled by default and it does not ...
0
votes
2answers
161 views

How to add a system call in linux kernel 4.x

I'm trying to add a system call using linux kernel 4.1.6 but all the documentation I can find is for older versions. Does anyone know how it's done in the newer kernels or have any good references? ...
1
vote
0answers
21 views

how practical the number of cores in Android

I've often wondered how practical the cores usage in Android smartphone. I'm asking here because Android is based on Linux. I'm looking from technical perspective. The articles that I've read so far ...
0
votes
1answer
487 views

How do you install the FreeBSD10 kernel sources?

I am trying to run an update of freebsd10 and I am being asked for the kernel sources ===>>> Launching child to update lsof-4.89.b,8 to lsof-4.89.d,8 ===>>> All >> ...
1
vote
0answers
28 views

Does this bug indicate an error in my btrfs filesystem of simply a bug in the 4.2.0-RC5 kernel?

I'm not sure this is the right place to ask this... I have been running a pre-release kernel (4.2.0-rc5) and yesterday had a possible disk error on my 6-disk raid-1 btrfs filesysystem. While trying ...
1
vote
0answers
22 views

Retrieve parent pid [migrated]

I am new to kernel module progrmming. In my program I need to display the process name and its parent's pid. The following is my simple_init() function int simple_init(void){ printk(KERN_INFO ...
0
votes
0answers
19 views

How do I track down why my system is unstable?

I am experiencing a problem where I use Chrome on my X220 with CentOS 7 (kernel 3.10.0-229.el7.x86_64). It begins when I've been surfing Chrome for a bit and have a few tabs open. Chrome may just ...
3
votes
2answers
691 views

What are the concepts of “kernel ring buffer”, “user level”, “log level”?

I often saw the words "kernel ring buffer", "user level", "log level" and some other words appear together. e.g. /var/log/dmesg Contains kernel ring buffer information. /var/log/kern.log ...
1
vote
1answer
21 views

What module in the kernel that inform the DHCP client to start DHCP negotiation?

DHCP client is a process instead of kernel code. How the DHCP client know when to start sending DHCP discover message? Is it the IP module in the kernel that inform the DHCP client?
0
votes
1answer
726 views

psmouse sync issues!

I have Compaq CQ61-420US (64-bit AMD) laptop with Synaptics touchpad checked using $ egrep -i 'synap' /proc/bus/input/devices N: Name="SynPS/2 Synaptics TouchPad" But recently after Arch Linux ...