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

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71
votes
5answers
35k 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. ...
63
votes
7answers
216k 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?
59
votes
10answers
80k 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
149k 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.
53
votes
9answers
52k 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.
51
votes
2answers
35k 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 ...
43
votes
1answer
1k 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 ...
41
votes
4answers
20k 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
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
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 ...
31
votes
9answers
124k 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
21k views

How can I determine the version of the running kernel?

How can I determine the version of the running kernel?
29
votes
3answers
43k 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
4answers
57k 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
9answers
56k 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 ...
28
votes
6answers
52k 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
45k 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
47k 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
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
34k 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
26k 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 ...
24
votes
1answer
13k 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 ...
23
votes
4answers
89k views

How do I install kernel header files?

i want to write a device driver but not able to find the header file can someone please help me find them?Also if someone can point out some important site links that would be really appreciated
23
votes
0answers
5k views

How to remove old kernel versions automatically? [duplicate]

I know number of ways to remove old kernel versions manually. Is there any way to remove old kernel versions automatically? Automatically, in the sense i don't have to do the same thing each time the ...
22
votes
3answers
14k views

What's the meaning of “-pae” at the end of kernel version?

Last time I installed Ubuntu there was a "-pae" at the end of the kernel version in the boot screen. Now that I've reinstalled Ubuntu from the same disk instead of "-pae" there is a "-generic" at the ...
22
votes
1answer
5k views

What is hardware enablement (HWE)?

I see the linux-hwe-generic package as part of the kernels you can install in Ubuntu 12.04. What is hardware enablement (HWE)?
22
votes
1answer
9k views

Quantal backported kernel in 12.04.2? What's going on there?

I'm sure that I'm not the first and/or only one to notice that 12.04.2, released earlier this year, installs by default a backported 3.5 kernel from the Quantal (12.10) release. I'm surprised to see ...
21
votes
8answers
33k views

What is a “Asking for cache data failed” warning?

I'm installing Ubuntu server 12.04 on Dell laptop and I frequently get an message as below: 3256.362200] sd 5:0:0:0: [sdb] Asking for cache data failed [3256.362200] sd 5:0:0:0: [sdb] Assuming drive ...
21
votes
4answers
37k views

How can I install a realtime kernel?

I have read a lot of threads with similar questions, but after reading the answers, I am very confused. I have found in them lots of url's with repositories but people discusses about which ...
21
votes
2answers
26k views

How to force installation of kernel updates when using apt-get upgrade?

To update my server I use apt-get upgrade. But when there are kernel updates I always need to do apt-get install linux-.... because apt-get update does not install them. Is there a way I can tell it ...
21
votes
2answers
13k views

What is the linux-image-extra package for and do I need it?

Good day everyone. I occasionally update my kernel from this web site http://kernel.ubuntu.com/~kernel-ppa/mainline/ I have been always downloading 3 deb files for installing linux header all, ...
20
votes
4answers
1k views

What has Ubuntu contributed to the Linux Kernel?

This question is similar to this one: What unique enhancements and features has Ubuntu brought to the Linux Community but in this case it is directed towards what has Ubuntu contributed to the ...
20
votes
2answers
5k views

Compile 32bit kernel on 64bit machine

I'm trying to compile a kernel for a 32bit single-core Intel Atom machine. Needless to say, the compile is taking inordinate amounts of time. It's been going for 2 hours and it's still only halfway ...
20
votes
2answers
15k views

How do I disable the blank console “screensaver” on Ubuntu Server?

How to disable blank screensaver on Ubuntu Server? There's no desktop or X, only console (command-line interface).
20
votes
1answer
6k views

What are the differences between linux-generic, linux-server and linux-virtual kernel packages?

I'm getting new VMs built for development and staging environments, and was wondering whether there are compelling reasons for or against using the linux-virtual package on all of these images. Do ...
19
votes
4answers
13k views

What is the meaning of 'i686' in Ubuntu?

To check whether I am using 32bit or 64bit Ubuntu. I looked in How do I check if I have a 32-bit or a 64-bit OS? and found this answer uname -a. If it is shown as i386, it will be 32bit and amd64, it ...
19
votes
2answers
24k views

vmplayer problem - VMWare Kernel Module Updater doesn't run since 13.04 upgrade

When I run vmplayer, it detects that the kernel has changed, and as usual prompts compile and load the required modules. However, it never gets any further. When you choose install, it just quits ...
19
votes
2answers
3k views

What's the fairest way to monitor total CPU time - per user?

On a multi user system, I want to measure each user's CPU usage in seconds of cpu time. For the purpose of this measurement, I assume that if a PID belongs to a user, this user is causing the CPU time ...
19
votes
0answers
40k views

How to remove kernels from previous release? [duplicate]

Possible Duplicate: Is there a way to remove/hide old kernel versions? I upgraded my Ubuntu 11.10 system to 12.04 using a CD. After upgrading I try to remove old version kernels that ...
18
votes
8answers
63k views

Unable to start VMWare Workstation after upgrade to 13.04

After upgrading to 13.04 I am unable to start VMWorkstation. I get the following message: Before you can run VMware, several modules must be compiled and loaded into the running kernel. ...
18
votes
4answers
39k views

get rid of kvm: disabled by bios

I'm getting a message: kvm:disabled by bios after upgrading my kernel to 3.8.x. I've never installed kvm package.neither I can enable virtualization from my bios, because of a bios bug. I wish I ...
18
votes
3answers
15k views

Can I update the kernel of my 10.04 LTS to the latest kernel?

I want to update the kernel version of my current 10.04 LTS to at least 2.6.37 (because the drivers for my eth0 and wlan0 interfaces are included in the said kernel). If it is possible, how do I do ...
17
votes
6answers
42k views

Kernel Panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

Upon trying to upgrade from 10.10 to 11.04 all seemed to go well until the restart. This error message is what comes up: Kernel Panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0) ...