Re: How to rebuild Woody kernel (Newbie)
WARNING: Much text follows. CC'd to list for archival purposes.
Kent
DSC Siltec wrote:
I've installed Woody, but have discovered that I don't have
(a) ALSA for my sound (alternately ymfpci.o) or
(b) support for my USB (which I assume will be necessary if I want to
upload my digital camera pictures to my Linux box.)
So I found out I have to rebuild my kernel. Never having done this
before,
I went to the Linux Kernel HOWTO, and pulled up HOWTO Rebuild the
Kernel.
The stuff looks like greek to me.
For one thing, it starts a person out in BASH, switches to X [do you
really need X to rebuild the kernel???
No.
], loops out to telnet terminals,
and gets me completely lost in the process.
For another thing, I am not at all sure which modules I'll be needing,
and it looks like I'll have to know that. I can pick up my filesystem
from module okay, and I can figure out my chip, and I can probably
safely assume that I have a PCI motherboard. But most of these things
were bypassed in the initial woody installation.
Not sure I can help a lot here.
Ideally, it would be nice to get a list of the modules that I already
have and their installation values -- I am sure that they would be
listed somewhere in ETC, if I knew where to look.
"modules" that have been built/installed will be in
/lib/modules/[kernel-version]. But that doesn't account for the things
that are compiled in (ie not "modules"). You can also look in
/usr/src/[kernel-version]/.config for clues, assuming you're not running
a pre-compiled kernel (which I suspect you are, since you don't know how
to compile a kernel).
So I was wondering -- are there any better howtos out there, possibly
more in line with Woody? Or is there a newbie guide on rebuilding the
kernel?
Anyhow, this looks like a fairly scary process when I may wreck the
system and have no idea what I am doing (kid at the wheel of a
steamroller syndrome... what's this button do?).
You won't break anything permanently by trying different things in your
configuration, so feel free to experiment/learn. As long as you're
fairly conservative in your choices, you most likely won't hose the
system too badly. You should be able to always fall back to your
previous working kernel if necessary.
I make no claims to this being a "better howto", but it should be more
Debian-specific.
Kent's 10-Step Procedure to Compiling a Debian Kernel
(I may leave a step or two out, but this is the gist)
1. Run "dselect". Choose "Update". Choose "Select". "space bar" to get
out of the Help screens. Use "/" (without the quotes) to start search.
Search for "kernel-source". Mark for installation the 2.4.18 or so.
1b. Use "/" to search for "kernel-package". Mark it for installation
also. "Enter" to get back to the main dselect menu.
1c. Choose "Install". This will download a file in /usr/src with a .tgz
extension, as well as install "kernel-package".
2. "cd /usr/src"
3. "gunzip kernel-source-2.4.18.tar.tgz" (or whatever the file is
named). This will unzip (decompress) the file.
4. "tar -xvf kernel-source-2.4.18.tar". This will untar the file (x
means extract, v means "be verbose", f means "use the file named ...").
A new subdirectory named kernel-source-2.4.18 will be created with all
the untarred files under it. You can also do steps 3 and 4 in one tar
command, but I never do; habit is the only reason. I think you just add
the "z" switch to tar, such as "tar -xvzf 'filename'".
5. "ln -s kernel-source-2.4.18 linux". This will create a symbolic link
("alias" in Mac-speak; "shortcut" in Windows-speak, but more powerful
than either) to the directory "kernel-source-2.4.18"; the symlink is
named "linux". This step is not absolutely necessary, but it's the usual
way of doing things. "ls -l" will show you that "linux" is a "pointer"
to "/etc/src/kernel-source-2.4.18".
Pause and Breathe. You now have the kernel sources installed. You
haven't done anything with them yet, but they're installed.
6. "cd /usr/src/linux" (which because linux is a symlink, accomplishes
the same thing as "cd /usr/src/kernel-source-2.4.18").
7. "make menuconfig". This will start a curses-based (text-based)
menu-driven application. There are a lot of choices here, and many of
them won't make sense to you at all. Take the time to look at most all
of them (some of them you'll know you don't need, like SCSI support if
you have an all-IDE system, or Amateur Radio Support if you're not a
ham) and read the HELP on them if they look relevant. A lot of the time
the HELP will suggest whether you should include it or not, and
generally when in doubt, leave things set the way they are. Some things
to check out:
* the correct processor for your system (AMD vs Pentium vs P4, etc)
* Symmetric Multi-Processing; "No" if you only have a single processor
* Loadable module support; "Yes" to all three sub-items.
* Parallel port support; "Yes" if you have a parallel printer. "No" to
keep things simple for now if you can live without the printer for a while.
* Plug-N-Play; "Yes"; ISA P-N-P; only if you have any ISA cards installed.
* Character devices; turn on Direct Rendering if your video card is
listed, and turn on agpgart if your video chipset is listed; mice if you
have a PS/2 mouse
* Sound - find the driver for your card
* Input core support (some USB stuff needs this, but I'm hazy on it -
use your best guess)
* USB support (make your best guesses; I'm hazy on it)
* You probably won't need to touch the following:
- General Setup
- Memory Technology
- Block devices
- Multi-device support
- Networking options
- Telephony support
- ATA/IDE/MFM/RLL support
- Fusion MPT device support
- I20 device support
- Amateur Radio support
- Infrared support
- ISDN subsystem
- Old CD-ROM drivers (unless you have a non-ATAPI CD-ROM drive
for now; wait till you've compiled a kernel or two)
- Multimedia devices (unless you have a tv tuner, etc; too
complicated for now; wait)
- File Systems (unless you'll be accessing a DOS/FAT/NTFS/etc
partition, or Windows shares via smb, etc)
- Console Drivers (play with different text modes at bootup)
- kernel hacking
It's by turning off unneeded stuff that the hackers get their kernels
down in size and up in efficiency. But you're not really worried about
either at this point.
7b. Exit and save your configuration. This will create a hidden file
named ".configure" in the "/usr/src/linux" directory. You could edit
this file directly to make changes to your configuration, but I
wouldn't. All that this step (7 and 7b)) has done is to set up this
configuration file. This file is read by the actual kernel compilation
process to compile the options you've specified.
Pause and breathe again. You have now configured your options for the
next kernel compilation, but you have not yet compiled it.
8. Compile the kernel: use the command "make-kpkg kernel_image". This
will cause a bunch of grinding and text; depending on the speed of your
computer and the options you chose, this could take minutes (fast
computer) to hours (slow computer). This step is a Debian-way of
compiling the kernel. The "other" way is to do it manually, which
consists of several steps such as "make dep" and "make modules" and
"make modules_install" and manually finding and moving the kernel to
where it needs to be and setting up symlinks and configuring lilo.conf
and running lilo. The Debian-way is much easier. The result will be a
file named something like "kernel-image-2.4.18_1.00.Custom_i386.deb",
one level up, in "/usr/src".
Pause and breathe. You have now compiled your kernel and made a .deb
file out of it for easy installation.
If you're (re)compiling a kernel with the same version number as your
current version, you'll probably want to run the command "mv
/lib/modules/2.[whateverversion] /lib/modules/2.[whateverversion].old"
to move the old modules out of the way in preparation for the creation
of new modules. I don't remember if this needs to be done before step 8
or before step 9, but it'll warn you that you need to do this before it
overwrites the old modules, and you can just open a new terminal and do
it then without canceling whichever step it concerns. This is only
applicable when (re)compiling the same version number of kernel as your
existing version.
9. Install the new .deb file. Use the command "dpkg -i
/usr/src/kernel-image-2.14.18*.deb". This will install the new kernel to
where it needs to be (and I believe configure /etc/lilo.conf) and run lilo.
Pause and breathe. You are ready for a reboot to start running your new
kernel. Make sure you have a backup method for getting into your box (a
Debian install CD, or boot floppy, etc) in case something goes wrong.
10. Reboot. After the reboot, you should be running the new kernel.
Typing "uname -a" will tell you what version of kernel you are running.
Test the machine and see if things work properly.
Pause, breathe, celebrate. You've successfully compiled and installed
your first kernel! You may not have a working sound card or USB stuff
yet, and other things may have broken, but now that you know the basic
procedure you can go back and try again.
Have fun!
Kent
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