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Is it true that the following shows that two versions of the kernel are being used? (Is the bold face -- the one enclosed in ** showing what is currently loaded / used). Basically, I just created a VM using VMWare Fusion on a Macbook Pro, downloaded Fedora (the current one, which is 17), installed it and did the upgrade it prompted me to do in a window.

(The ones I see are kernel.x86_64 3.3.4-5.fc17 and kernel.x86_64 3.6.10-2.fc17, so 3.3.4 and 3.6.10 are both running? How come the other kernel parts like headers, modules, or tools don't need to be running?)

$ yum list kernel-*
Loaded plugins: langpacks, presto, refresh-packagekit
(1/2): fedora/primary_db                                 |  14 MB     00:13     
(2/2): updates/primary_db                                | 7.3 MB     00:06     
Installed Packages
**kernel.x86_64**                       3.3.4-5.fc17    @koji-override-0/$releasever
**kernel.x86_64**                       3.6.10-2.fc17   @updates                    
Available Packages
kernel-debug.x86_64                 3.6.10-2.fc17   updates                     
kernel-debug-devel.x86_64           3.6.10-2.fc17   updates                     
kernel-debug-modules-extra.x86_64   3.6.10-2.fc17   updates                     
kernel-devel.x86_64                 3.6.10-2.fc17   updates                     
kernel-doc.noarch                   3.6.10-2.fc17   updates                     
kernel-headers.x86_64               3.6.10-2.fc17   updates   
kernel-modules-extra.x86_64         3.6.10-2.fc17   updates                     
kernel-tools.i686                   3.3.4-5.fc17    fedora                      
kernel-tools.x86_64                 3.6.10-2.fc17   updates 

  [...]
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Yes, you have two kernels installed. For future reference, this may come in useful if after an update you find bugs under the newer kernel. Then you can select the older one manually (e.g. in GRUB you have to press a key - say, Shift, during machine bootup to get the menu to choose the kernel from). It is always a good practice to keep at least two (sometimes three, if you don't spot the bug right away) kernel versions handy. –  Deer Hunter Jan 5 '13 at 5:50
    
I usually try to keep three. 1. The kernel the distribution was installed with. 2. The most recent known working kernel. 3. The updated version being tested and run. When a new #3 is released and the existing #3 kernel has been working properly, I will remove #2 and the existing #3 becomes the #2 kernel. –  Rob Gibson Jan 5 '13 at 17:25
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2 Answers 2

Yum is not showing the running kernel(s)... You cannot have multiple kernels running simultaneously in a single userspace.

Yum is showing you the installed kernels. Most likely, you are running the 3.6.10 kernel, although checking on it is as simple as running uname -a.

The additional lines are supplementary packages which add additional capabilities to the system. For example, the kernel -devel package is the entire kernel source. This allows you to rebuild the kernel or to build a custom module against that kernel.

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Fedora tries to keep several kernels around (by default 3), in case some boot fails horribly and you have to go back to an older one.

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