| 1 |
<?xml version="1.0" encoding="UTF-8"?> |
| 2 |
<!-- $Header: $ --> |
| 3 |
|
| 4 |
<!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> |
| 5 |
<guide link="kernel-upgrade.xml"> |
| 6 |
<title>Gentoo Linux Kernel Upgrade Guide</title> |
| 7 |
<author title="Author"> |
| 8 |
<mail link="dsd@gentoo.org">Daniel Drake</mail> |
| 9 |
</author> |
| 10 |
|
| 11 |
<abstract> |
| 12 |
This document describes the process of upgrading your kernel from one release |
| 13 |
to another. |
| 14 |
</abstract> |
| 15 |
|
| 16 |
<!-- The content of this document is licensed under the CC-BY-SA license --> |
| 17 |
<!-- See http://creativecommons.org/licenses/by-sa/2.0 --> |
| 18 |
<license/> |
| 19 |
|
| 20 |
<version>0.1.0</version> |
| 21 |
<date>November 1st, 2004</date> |
| 22 |
|
| 23 |
<chapter> |
| 24 |
<title>Introduction</title> |
| 25 |
<section> |
| 26 |
<body> |
| 27 |
|
| 28 |
<p> |
| 29 |
The kernel is one of the few package classes in portage that requires some |
| 30 |
manual intervention to complete the upgrade. Portage will download and |
| 31 |
install the kernel source for you, but then it is up to you to step in and |
| 32 |
compile the new kernel before any changes will take effect. |
| 33 |
</p> |
| 34 |
|
| 35 |
<p> |
| 36 |
Although this guide is targetted at users upgrading from one kernel release |
| 37 |
to another, it will also be useful for users migrating from one kernel |
| 38 |
package to another. |
| 39 |
</p> |
| 40 |
|
| 41 |
<p> |
| 42 |
<c>gentoo-dev-sources</c> is used as an example in this document, however, the |
| 43 |
instructions here also apply to the other packages present in our tree. |
| 44 |
</p> |
| 45 |
|
| 46 |
</body> |
| 47 |
</section> |
| 48 |
</chapter> |
| 49 |
|
| 50 |
<chapter> |
| 51 |
<title>Why upgrade kernel?</title> |
| 52 |
<section> |
| 53 |
<body> |
| 54 |
|
| 55 |
<p> |
| 56 |
Generally, upgrading from one minor kernel release to the next won't bring any |
| 57 |
major differences. Reasons for upgrading kernel are generally either to take |
| 58 |
advantage of a specific new feature or driver, to be protected against a |
| 59 |
security vulnerability, or just to maintain an up-to-date and healthy system. |
| 60 |
</p> |
| 61 |
|
| 62 |
<p> |
| 63 |
Even if you choose not to update to every new kernel revision, it is |
| 64 |
recommended that you at least upgrade from time to time. It is strongly |
| 65 |
recommended that you immediately upgrade to a new kernel if that new release |
| 66 |
solves a security problem. |
| 67 |
</p> |
| 68 |
|
| 69 |
</body> |
| 70 |
</section> |
| 71 |
</chapter> |
| 72 |
|
| 73 |
<chapter> |
| 74 |
<title>Obtaining the newer sources through Portage</title> |
| 75 |
<section> |
| 76 |
<body> |
| 77 |
|
| 78 |
<p> |
| 79 |
You upgrade the kernel sources like you would upgrade any other package - |
| 80 |
using the <c>emerge</c> utility. It will probably be the case that you want to |
| 81 |
upgrade your kernel when you see the upgrade appearing on your world updates |
| 82 |
list. For example: |
| 83 |
</p> |
| 84 |
|
| 85 |
<pre caption="New kernel sources appearing on update list"> |
| 86 |
# <i>emerge -Dup world</i> |
| 87 |
Calculating dependencies ...done! |
| 88 |
[ebuild U ] sys-kernel/gentoo-dev-sources-2.6.9-r2 [2.6.8-r5] |
| 89 |
</pre> |
| 90 |
|
| 91 |
<p> |
| 92 |
You can then go ahead and install the update, e.g.: |
| 93 |
</p> |
| 94 |
|
| 95 |
<pre caption="Upgrading your kernel sources"> |
| 96 |
# <i>emerge -u gentoo-dev-sources</i> |
| 97 |
</pre> |
| 98 |
|
| 99 |
<p> |
| 100 |
The kernel sources will then be installed into a subdirectory of |
| 101 |
<path>/usr/src</path>. In the above example, my new kernel sources will be |
| 102 |
installed at <path>/usr/src/linux-2.6.9-gentoo-r2</path>. |
| 103 |
</p> |
| 104 |
|
| 105 |
</body> |
| 106 |
</section> |
| 107 |
</chapter> |
| 108 |
|
| 109 |
<chapter> |
| 110 |
<title>Updating the /usr/src/linux symbolic link</title> |
| 111 |
<section> |
| 112 |
<body> |
| 113 |
|
| 114 |
<p> |
| 115 |
Gentoo requires you to maintain a symbolic link, located at |
| 116 |
<path>/usr/src/linux</path>. This should point to the sources of the |
| 117 |
kernel you are running. |
| 118 |
</p> |
| 119 |
|
| 120 |
<p> |
| 121 |
In this case, we need to update the symbolic link to point at the kernel |
| 122 |
sources that we are about to upgrade to. Continuing our example: |
| 123 |
</p> |
| 124 |
|
| 125 |
<pre caption="Updating the /usr/src/linux softlink"> |
| 126 |
# <i>cd /usr/src</i> |
| 127 |
# <i>ln -sf linux-2.6.9-gentoo-r2 linux</i> |
| 128 |
</pre> |
| 129 |
|
| 130 |
</body> |
| 131 |
</section> |
| 132 |
</chapter> |
| 133 |
|
| 134 |
<chapter id="install"> |
| 135 |
<title>Configuring, compiling and installing the new kernel</title> |
| 136 |
<section> |
| 137 |
<body> |
| 138 |
|
| 139 |
<p> |
| 140 |
For either of these options, you should refer to the instructions given in the |
| 141 |
<uri link="http://www.gentoo.org/doc/en/handbook/index.xml">Gentoo |
| 142 |
Handbook</uri> relating to <e>Configuring the Kernel</e> and <e>Configuring |
| 143 |
the Bootloader</e>. A quick summary is provided here. |
| 144 |
</p> |
| 145 |
|
| 146 |
</body> |
| 147 |
</section> |
| 148 |
<section> |
| 149 |
<title>Option 1: Automatic kernel setup with Genkernel</title> |
| 150 |
<body> |
| 151 |
|
| 152 |
<p> |
| 153 |
If you are a genkernel user, you just need to repeat the stages you went |
| 154 |
through when installing your kernel for the first time. |
| 155 |
</p> |
| 156 |
|
| 157 |
<p> |
| 158 |
Simply run genkernel in the normal way: |
| 159 |
</p> |
| 160 |
|
| 161 |
<pre caption="Invoking genkernel"> |
| 162 |
# <i>genkernel all</i> |
| 163 |
</pre> |
| 164 |
|
| 165 |
<p> |
| 166 |
You can also use extra parameters for other genkernel functionality. For |
| 167 |
example, if you wish to configure some extra kernel options using |
| 168 |
<c>menuconfig</c> and you wish genkernel to automatically update your grub |
| 169 |
bootloader config, then invoke genkernel as follows: |
| 170 |
</p> |
| 171 |
|
| 172 |
<pre caption="Invoking genkernel with some common arguments"> |
| 173 |
# <i>genkernel --menuconfig --bootloader=grub all</i> |
| 174 |
</pre> |
| 175 |
|
| 176 |
<p> |
| 177 |
For more info, follow the |
| 178 |
<uri link="http://www.gentoo.org/doc/en/genkernel.xml">Gentoo Linux Genkernel |
| 179 |
Guide</uri>, or refer to the handbook. |
| 180 |
</p> |
| 181 |
|
| 182 |
</body> |
| 183 |
</section> |
| 184 |
<section> |
| 185 |
<title>Option 2: Manual configuration</title> |
| 186 |
<body> |
| 187 |
|
| 188 |
<p> |
| 189 |
To begin, open the <c>menuconfig</c> utility in the kernel source tree: |
| 190 |
</p> |
| 191 |
|
| 192 |
<pre caption="Invoking menuconfig"> |
| 193 |
# <i>cd /usr/src/linux</i> |
| 194 |
# <i>make menuconfig</i> |
| 195 |
</pre> |
| 196 |
|
| 197 |
<p> |
| 198 |
Select the options required for your hardware and operating environment. Refer |
| 199 |
to the <e>Gentoo Handbook</e> for additional guidance on this. |
| 200 |
</p> |
| 201 |
|
| 202 |
<p> |
| 203 |
Next, compile your kernel and copy it over to your boot partition. Again, |
| 204 |
follow the handbook instructions here, but don't forget to mount your /boot |
| 205 |
partition first! In the initial installation, you would have already mounted |
| 206 |
this at a much earlier stage. |
| 207 |
</p> |
| 208 |
|
| 209 |
<pre caption="Compiling and installing the new kernel"> |
| 210 |
# <i>make && make modules_install</i> |
| 211 |
# <i>mount /boot</i> |
| 212 |
# <i>cp arch/i386/boot/bzImage /boot/bzImage-2.6.9-gentoo-r2</i> |
| 213 |
# <i>cp System.map /boot/System.map-2.6.9-gentoo-r2</i> |
| 214 |
</pre> |
| 215 |
|
| 216 |
<p> |
| 217 |
Finally, you should update your bootloader config, adding an entry for the |
| 218 |
new kernel (don't delete the old one just yet!) and unmount the |
| 219 |
<path>/boot</path> partition. Again, refer to the handbook for instructions |
| 220 |
here. |
| 221 |
</p> |
| 222 |
|
| 223 |
</body> |
| 224 |
</section> |
| 225 |
</chapter> |
| 226 |
|
| 227 |
<chapter> |
| 228 |
<title>Reinstalling external modules</title> |
| 229 |
<section> |
| 230 |
<body> |
| 231 |
|
| 232 |
<p> |
| 233 |
If you use any kernel modules that are not included in the kernel source tree |
| 234 |
but are provided elsewhere in portage (e.g. Nvidia or ATI graphics drivers), |
| 235 |
then you must reinstall these on every kernel upgrade. This is as simple as |
| 236 |
re-merging the packages involved. Refer again to the |
| 237 |
<uri link="http://www.gentoo.org/doc/en/handbook/index.xml">Gentoo |
| 238 |
Handbook</uri> <e>Configuring the Kernel</e> chapter for more info here. |
| 239 |
Re-merging these packages will ensure they build against the source tree at |
| 240 |
<path>/usr/src/linux</path> - therefore they will actually being installed |
| 241 |
for the kernel we just compiled. |
| 242 |
</p> |
| 243 |
|
| 244 |
</body> |
| 245 |
</section> |
| 246 |
</chapter> |
| 247 |
|
| 248 |
<chapter> |
| 249 |
<title>Rebooting into the new kernel</title> |
| 250 |
<section> |
| 251 |
<body> |
| 252 |
|
| 253 |
<p> |
| 254 |
Next, close all applications and reboot your system. If you followed the above |
| 255 |
instructions correctly, you will see an entry for your new kernel on your |
| 256 |
bootloader. Select the new kernel and let the system boot. |
| 257 |
</p> |
| 258 |
|
| 259 |
<p> |
| 260 |
Hopefully, your system will boot without problem and you can log in and start |
| 261 |
working as usual. If everything is working, then the upgrade is complete at |
| 262 |
this stage. |
| 263 |
</p> |
| 264 |
|
| 265 |
<p> |
| 266 |
If you have made a mistake and your system will not boot into the new kernel, |
| 267 |
then you can simply reboot and boot into your previous working kernel. You can |
| 268 |
then restart from the <uri link="#install">Configuring, compiling, and |
| 269 |
installing the new kernel</uri> stage - making the appropriate changes to |
| 270 |
correct your mistake. In some cases (e.g. you just missed a network driver) |
| 271 |
then you might not even need to reboot to do this. |
| 272 |
</p> |
| 273 |
|
| 274 |
</body> |
| 275 |
</section> |
| 276 |
</chapter> |
| 277 |
|
| 278 |
<chapter> |
| 279 |
<title>Running multiple kernels</title> |
| 280 |
<section> |
| 281 |
<body> |
| 282 |
|
| 283 |
<p> |
| 284 |
You may have noticed, that when installing the sources for your newer kernel, |
| 285 |
the sources for your existing kernel were not removed. This is by-design and |
| 286 |
allows you to easily switch between running different kernels. |
| 287 |
</p> |
| 288 |
|
| 289 |
<p> |
| 290 |
Switching between multiple kernels is as simple as leaving the kernel sources |
| 291 |
under <path>/usr/src/</path> and leaving the <path>bzImage</path> binaries on |
| 292 |
your <path>/boot</path> partition (referenced by entries in your bootloader |
| 293 |
config). Every time you boot up, you will be presented with a choice of which |
| 294 |
kernel to boot into. |
| 295 |
</p> |
| 296 |
|
| 297 |
</body> |
| 298 |
</section> |
| 299 |
</chapter> |
| 300 |
|
| 301 |
<chapter> |
| 302 |
<title>Removing older kernels</title> |
| 303 |
<section> |
| 304 |
<body> |
| 305 |
|
| 306 |
<p> |
| 307 |
Continuing on from the last section, you may be happy with your new kernel and |
| 308 |
not have any need to keep older kernel versions around. To easily remove all |
| 309 |
sources for a particular kernel except for the newest one, you can take |
| 310 |
advantages of emerge's <e>prune</e> option. Continuing the example using |
| 311 |
gentoo-dev-sources: |
| 312 |
</p> |
| 313 |
|
| 314 |
<pre caption="Pruning old versions"> |
| 315 |
# <i>emerge -P gentoo-dev-sources</i> |
| 316 |
</pre> |
| 317 |
|
| 318 |
<p> |
| 319 |
In most cases, temporary files used during compilation will still remain under |
| 320 |
the appropriate source directory under <path>/usr/src</path>. It is safe to |
| 321 |
remove these using <c>rm</c>. |
| 322 |
</p> |
| 323 |
|
| 324 |
<p> |
| 325 |
You can also safely delete any modules that were used by this kernel. This can |
| 326 |
be done by removing the appropriate directories under <path>/lib/modules/</path> |
| 327 |
that relate to the kernel versions you are removing. Be careful not to delete |
| 328 |
modules belonging to kernels that you still use! |
| 329 |
</p> |
| 330 |
|
| 331 |
<p> |
| 332 |
Finally, you can mount your <path>/boot</path> partition and remove the |
| 333 |
<path>bzImage</path> and <path>System.map</path> files for the kernel(s) |
| 334 |
you are pruning. You should also edit your bootloader config so that it |
| 335 |
no longer references this kernel. |
| 336 |
</p> |
| 337 |
|
| 338 |
</body> |
| 339 |
</section> |
| 340 |
</chapter> |
| 341 |
|
| 342 |
<chapter> |
| 343 |
<title>Problems after a kernel upgrade?</title> |
| 344 |
<section> |
| 345 |
<body> |
| 346 |
|
| 347 |
<p> |
| 348 |
With the rapid development of the Linux kernel, it is inevitable that some |
| 349 |
changes made from one kernel release to another may cause some problems. If |
| 350 |
you have any issues with the latest versions of |
| 351 |
<uri link="http://www.gentoo.org/doc/en/gentoo-kernel.xml#doc_chap2"> |
| 352 |
Gentoo-supported kernels</uri> then please do report the issues to us. |
| 353 |
</p> |
| 354 |
|
| 355 |
</body> |
| 356 |
</section> |
| 357 |
</chapter> |
| 358 |
|
| 359 |
</guide> |
Parent Directory
| 
Revision Log