1 Gentoo:Kernel Cleanup
2 =====================
3 :author: Aaron Ball
4 :email: nullspoon@iohq.net
5 :revdate: October 30, 2015
6
7
8 Gentoo is a source-based Linux distribution. Moreover it's aimed at more
9 advanced users with the intent of not forcing anything on them, as much as is
10 possible with so many packages.
11
12 Normally, whenever you get a kernel update on a distro, say from 4.2.0 to
13 4.2.5, the system does several things.
14
15 * Download the new kernel (pre-compiled)
16 * Install the new kernel
17 * Update the initramfs
18 * Update the bootloader
19 * Clean up the unused kernels
20
21 Gentoo requires that their users to each of those items. I'm fairly new to
22 Gentoo and, coming from Arch Linux, already knew for the most part how to do
23 all of those steps, except for the last one. That said, lets talka bout how to
24 clean up unused kernels on your system.
25
26 == TL;DR Summary
27
28 Here are the locations that need to be cleaned up, in case you want to skip to
29 that section or already know what you're doing but just need the list.
30
31 * emerge -C <sys-kernel/<type>-sources-<version> _(This is specific to Gentoo)_
32 * Files
33 * /usr/src/linux-<versions>
34 * /lib/modules/<versions>
35 * /boot/*-<versions>
36
37
38 == Inventory
39
40 The first step is to take an inventory. The largest part of a kernel in Gentoo
41 is its source code, so we'll look at that for the inventory (there are other
42 ways and we'll look into those as well).
43
44 Gentoo stores its kernel source at _/usr/src/linux-*_. In there, you can see
45 multiple versions of the linux source code. In my case, I have linux-4.2.0 all
46 the way up to linux 4.2.5.
47
48 NOTE: In my case, I'm using vanilla-sources for my kernel, so the directory
49 names for you might be a tad different. Despite though, they should still start
50 with _linux-x.x.x*_.
51
52
53 == Clean Up the Source
54
55 Now that we have an inventory, let's clean up the source. This is very simple.
56 Once you know what versions you want to keep, we can issue an emerge command
57 that will clean up the files for the source. For my example, we'll say we want
58 to remove anything before 4.2.4
59
60 emerge -Cp <sys-kernel/vanilla-sources-4.2.4
61
62 That command will delete any files installed by emerge if they belong to kernel
63 versions 4.2.3 or less. However, it doesn't clean up any files created by the
64 compile process, so we still need to remove those.
65
66 To see where we are first, here's an ls example of my src directory.
67
68 0 [nullspoon@null ~]$ ls /usr/src/
69 linux linux-4.2.0 linux-4.2.1 linux-4.2.2 linux-4.2.3 linux-4.2.4 linux-4.2.4-gentoo linux-4.2.5 linux-4.2.5-gentoo
70
71 Now for a simple but gratifying rm command. Since rm has no knowledge of the
72 kernel versioning scheme, we can't say "less than version 4.2.4" and it'll
73 clean up. In this case, we'll use a simple bash sequence.
74
75 rm -rf /usr/src/linux-4.2.{0,1,2,3}
76
77 NOTE: If you are worried about running that command and what it'll do, run it
78 with echo before it to see what it will output without actually deleting
79 anything.
80
81
82 == Clean up Installed Modules
83
84 The Linux kernel stores its modules in */lib/modules* (fun fact: /lib is
85 usually a symlink to /lib64 if you're running a 64 bit system, or /lib32 if
86 you're running a 32 bit system).
87
88 Similar to cleaning up the sources, we will clean up the moduels with a simple
89 but gratifying _rm -rf_ command.
90
91 rm -rf /lib/modules/4.2.{0,1,2,3}
92
93 That will clean up all the installed modules for the specified old kernel
94 versions (in this case, 4.2.0, 4.2.1, etc).
95
96
97 == Clean up Old Installed Kernels
98
99 The Linux Kernel installs itself to _/boot_. To see what you have for the
100 given version set (again, using the one from previous examples, run the
101 following command...
102
103 ls /boot/*-4.2.{0,1,2,3}
104
105 Again, a simple rm command will clean up these files.
106
107 rm -f /boot/*-4.2.{0,1,2,3}
108
109
110 And with that, you're done. All clean!
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115 [role="datelastedit"]
116 Last edited: {revdate}
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118 // vim:set syntax=asciidoc:
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