for questions concerning Ubuntu's kernel, including compiling and questions relating to modules

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73
votes
5answers
37k views

Why is swap being used even though I have plenty of free RAM?

I thought the whole essence of swap was to act as a temporary storage safety net when RAM was full but my swap partition is constantly being used even though I sometimes have as much as 3GB free RAM. ...
64
votes
7answers
219k views

How can I install on a non-PAE CPU? (error “Kernel requires features not present on the CPU: PAE”)

After burning Ubuntu 12.04 to a CD, I tried booting and got the message: This kernel requires the following features not present on the CPU: pae Unable to boot - please use a kernel appropriate for ...
61
votes
6answers
10k views

How do we get this magic performance-boosting 200 line patch?

I read today on Phoronix that there is a 200 line patch to the Linux Kernel which dramatically improves desktop responsiveness. How can Ubuntu users get this in a way that's supported?
61
votes
10answers
81k views

Desktop does not show when I installed nvidia drivers!

The desktop does not show after I installed nvidia experimental drivers. I tried nvidia simple proprietary drivers, and they did not work either. Here is how it looks. This is not cropped or any ...
57
votes
8answers
153k views

What is the path to the kernel headers so I can install vmware?

I installed the VMware bundle on my Ubuntu 11.04 successfully but when I open it it gives me this window and I don't know the path to this C headers.
56
votes
2answers
37k views

Can't upgrade due to low disk space on /boot

I try to do do-release-upgrade but then I get: Not enough free disk space The upgrade has aborted. The upgrade needs a total of 25.7 M free space on disk '/boot'. Please free at least an ...
53
votes
9answers
53k views

Does Ubuntu support USB 3.0?

I have a Western Digital My Book 3.0 - 1 TB USB 3.0 Desktop External Hard Drive, and I wanted to know if it would work on Ubuntu 10.10 Maverick Meerkat.
43
votes
1answer
2k views

What is Ubuntu's policy on keeping old kernels

I've just run out of disk space on /. Looking into the situation I realised that since first installing 12.04, Ubuntu has upgraded the kernel ~23 times and has kept every old kernel, binaries and ...
42
votes
4answers
21k views

How do I install and use flashcache/bcache to cache HDD to SSD?

I want to know if there is anyone who has tried installing and running their kernel built with flashcache or bcache for SSD caching? How did you manage to do it?
36
votes
2answers
3k views

Does the removal of i386 from the kernel mean Ubuntu is dropping 32 bit support?

I saw recently that the i386 CPU is not going to be supported in the Linux Kernel 3.8 so does that mean that Ubuntu will only be available in the coming years in 64-bit?
34
votes
3answers
40k views

Can I install Linux kernel in Ubuntu appart of the default one?

Can we install the latest kernel 3.4 in Kubuntu or Ubuntu 12.04 LTS? If not then please clarify the reason.
32
votes
2answers
14k views

What is kernel panic?

I just completed an OS course. I heard the phrase "kernel panic" a lot. Can you explain What is a kernel panic? Why does it occur? How can I find out that a kernel panic occurred? What effect does ...
32
votes
1answer
24k views

Is “laptop-mode-tools” still relevant for 12.04 and the 3.x kernels?

I'm using Ubuntu 12.04 x64 and trying to choose power management software. Laptop-mode-tools have a lot of features, but the only reason why I'm worry about is that it's manual and config files are ...
31
votes
9answers
127k views

How to update kernel to the latest mainline version without any Distro-upgrade?

Currently I'm running Linux-3.0 and I want to update it to Linux-3.3.1 the latest stable kernel release as mentioned at http://www.kernel.org. Can I update to 3.3.1 in Ubuntu without any risk of ...
31
votes
5answers
22k views

Does Ubuntu have support for the TRIM command for use with SSD?

SSD drives need to be "cleared/reset" after the drive fills up to maintain performance. This is done through the TRIM command for new SSD drives. Does Ubuntu support the TRIM command (through hdparm ...
30
votes
4answers
22k views

How can I determine the version of the running kernel?

How can I determine the version of the running kernel?
30
votes
3answers
46k views

How do I add a kernel boot parameter?

I need to add the boot parameter foo=bar to my kernel. How can I do this once for testing, and permanently if testing was a success?
29
votes
9answers
58k views

Error: kernel headers not found. (But they are in place)

I'm trying to install the Guest Additions in VirtualBox 4.04. Host OS is Ubuntu desktop 11.04 64bit, guest OS is Ubuntu server 11.10 64bit. $ sudo ./VBoxLinuxAdditions.run After some output this ...
29
votes
4answers
58k views

How can I upgrade the Ubuntu LTS kernel to newer?

I just installed Ubuntu 12.04.2 64-bit on my desktop PC and I see the kernel in System Monitor is 3.5.0-23 but in Ubuntu 12.04.2 in my laptop the kernel is 3.2.0-38. I have already tried to run the ...
28
votes
6answers
53k views

VirtualBox doesn't load after 12.04 upgrade

After upgrading from 11.10 to 12.04, virtual box stopped working. I've run the following to try to fix it: sudo aptitude update sudo aptitude install dkms sudo /etc/init.d/vboxdrv setup but when ...
27
votes
3answers
46k views

What does the kernel boot parameter “set acpi_osi=Linux” do?

I am facing an issue with brightness control in my laptop which has Intel HD graphics and Ubuntu 10.10 64-bit. So when I searched for a fix I found that a common suggestion is to edit the GRUB file ...
27
votes
5answers
4k views

Why does Ubuntu need to update its kernel so often?

What are the advantages for updating so often?
26
votes
5answers
21k views

Will Linux Kernel 3.5 be coming to 12.04?

I'm wondering if Kernel 3.5 or 3.6 will be available for Ubuntu 12.04 when the Kernel is officially released?
26
votes
4answers
48k views

Why to choose low latency kernel over generic or realtime ones?

After installing Ubuntu Studio 12.04, I found that it uses a low latency kernel. I searched why and how to change back to realtime or generic ones. But, looks like this part of Linux hasn't been ...
26
votes
1answer
14k views

Should I upgrade to the “mainline” kernels?

Newer "mainline" versions of the kernel are available from the Ubuntu kernel team, e.g. 3.4 and 3.5, while Ubuntu 12.04 is on 3.2. What are the mainline kernels? Are they better than my existing ...
26
votes
6answers
17k views

High temperature in a AMD Radeon HD4000/3000 series after upgrade

I was running 12.04 with Unity 3D for 6 months; my laptop ran almost silently and cool enough to hold on my lap with ~4 hours of battery life. I updated to 12.10 and switched to the Gnome 3 Shell. Now ...
25
votes
3answers
2k views

What are the differences between the Ubuntu shipped kernel and the upstream kernel?

What are the differences in feature set between the main Linux kernel and the kernel being used by Ubuntu? Why is Ubuntu branched off of the main kernel instead of using the main kernel directly?
24
votes
3answers
36k views

How to restore a system after accidentally removing all kernels?

I was trying to delete old kernels, but I must have deleted all of the kernels on my Ubuntu 11.04 laptop. Is there any way to fix this via USB boot or mounting hard drive on another system?
24
votes
3answers
29k views

What is the safest way to clean up /boot partition?

I've got 200 MB assigned for the /boot partition. Everytime I try to update the kernel I get an error message that basically says the size of /boot is full. What can I do to cleanup /boot and ...
12
votes
2answers
9k views

How can I tell if I am out of inotify watches?

I use an application that consumes inotify watches. I've already set fs.inotify.max_user_watches=32768 in /etc/sysctl.conf but last night the application stopped indexing unless I ran it manually, ...
8
votes
2answers
11k views

How to skip kernel update?

I am running Ubuntu 12.04.1 LTS i686 on VirtulBox. Every time I check the updates, there's a new Linux kernel. If I install the new kernel, I have to install the Virtulbox Guest Additions again and ...
5
votes
2answers
112 views

Why doesn't apt-get autoremove remove my old kernels?

My boot partition is on a SSD, so it doesn't have room for more than about 8 installed kernel versions, and eventually some kernel update will fail to install because my boot partition is full of old ...
3
votes
4answers
11k views

How long does it take to compile a kernel (linux 3.2.5)? [closed]

How long does it take to install kernel (linux 3.2.5) on 12.04 using make install -j 4 command? My terminal is displaying this for around 40 minutes now. root@user-desktop:/usr/src/linux-3.2.5# make ...
2
votes
1answer
30 views

Update all software with update manager XUbuntu 12.04.1 without updating kernel

I'm running a laptop with mobility radeon hd 4330 and I have to run kernel <= 3.2 for the proprietary legacy drivers to work. How can I update the packages on my system using the update manager ...
2
votes
0answers
23 views

kernel panic on boot

I'm having some trouble booting ubuntu 14.04. The most weird thing is that after the kernel panic error shows up, if I restart the laptop, grub appears (not showing up when the panic occurred), and ...
1
vote
1answer
47 views

How to verify zswap running?

How can I check to verify that zswap is enabled and working on my system?
1
vote
1answer
244 views

Beep at resuming from suspend

Since the upgrade from Precise to Quantal, the kernel beeps (quite loud) when waking from suspend. Is there a way to disable the beep?
1
vote
0answers
14 views

How do I load a module that has no signature in ubuntu 12.04?

I've got a custom module for a Mightex camera that has been tested for ubuntu 12.04 which I'm using. I have installed it however something is not working. I think it has to do with this dmesg output: ...
1
vote
0answers
456 views

“ERROR: Kernel configuration is invalid”

I have been stuck on this issue for two days now and couldnt find a fix for this. I installed a realtime kernel with sudo apt-get install linux-rt because KauNet (which is an ipfw extension) ...
1
vote
1answer
4k views

How can I revert to the previous kernel version w/out dependency issues?

Since ubuntu updated my install to 3.2.0-37-generic, my laptop fan constantly runs. I never had this issue with the previous kernel versions. To fix this problem, I would like to revert back to the ...
0
votes
1answer
26 views

Where is kernel/user.c?

I am doing some changes on ubuntu linux source code. I used find / -name user.c command to locate user.c but failed. Where is it? My working environment is ubuntu14.04.
0
votes
0answers
8 views

install openstack Juno on Ubuntu 12.10 or 13.04

i have Vlan issues with Ubuntu Trusty 14.04 since its using kernel 3.13 i need linux kernel 3.3 or higher (according to https://github.com/openvswitch/ovs/blob/master/FAQ.md Q: VLANs don't work.) ...
0
votes
1answer
4 views

Why am I getting “trusty” in a path while running ubuntu 12.04?

I'm running ubuntu 12.04 and on a different partition there is a ubuntu 14.04 distribution. When running dmesg one entry is the following: [ 3161.519138] WARNING: CPU: 1 PID: 4782 at ...
0
votes
1answer
9 views

Where can i find linux 3.8.11 kernel image in order to build wacom drivers for Samsung Chromebook 2

New to Ubuntu/Linux, so please bare with me. My setup: Samsung Chromebook 2 -> running Ubuntu via crouton (trusty with KDE). Im in the process of installing the Wacom Intuos drawing tablet, and i ...
0
votes
1answer
43 views

Unable to boot Ubuntu 14.04 after installing systemd-services and changing the init parameter on boot

I tried two different methods but could not install systemd 1st method from here, 2nd method from here Confirmation that systemd is not installed: edward@computer:~$ file /lib/systemd/systemd ...
0
votes
1answer
19 views

Right way to completely clean up old kernels in terminal

I have been going through various questions about how to clean up old Linux kernels. They all seem to have different answers and they are old, so someone is bound to say the question is too old and ...
0
votes
0answers
193 views

kworker/0:2 high cpu usage

I just install Ubuntu 14.04 on a brand new Toshiba Satellite and notice high usage of one of the cores on th cpu (over 95%), running a perf record I found this: 20,69% swapper ...
0
votes
0answers
45 views

How do you rebuild and apply a portion of the kernel?

I was following the steps here to build my own kernel, which worked great, then I wanted to make a small tweak to the setup file (/arch/x86/kernel/setup.c) and rebuild it to see my message printed in ...
0
votes
0answers
147 views

VMPlayer does not flush all outputs to serial port

I am debugging a Linux kernel in the VMPlayer on Ubuntu 12.04 configured a serial port to a file to see the debug information. However, each time when the kernel panics, only the backtrace stack were ...
-1
votes
0answers
35 views

Ubuntu not returning from suspend after kernel 3.13.0-36-generic

The latest kernel I have now is 3.13.0-40-generic but since upgrading from 3.13.0-36-generic none of the kernels have allowed my system to resume from suspend. I have to power cycle to get back in. ...