Knoppix Custom Kernel Howto - Revision history

Clinton: rd dea links

2008-10-16T12:24:48Z

rd dea links

Flamesrule89: /* FINAL NOTES */

2007-03-09T19:39:57Z

‎FINAL NOTES

Flamesrule89: 3MB ISO limit explained.

2007-03-09T19:38:52Z

3MB ISO limit explained.

Flamesrule89: /* ALTERNATIVE WAYS TO BOOT */

2007-03-09T19:16:20Z

‎ALTERNATIVE WAYS TO BOOT

Eadz: /* PREPARING YOUR DEVELOPMENT ENVIRONMENT */

2005-02-27T05:21:53Z

‎PREPARING YOUR DEVELOPMENT ENVIRONMENT

Eadz at 05:21, 27 February 2005

2005-02-27T05:21:26Z

Show changes

Dean thinker at 14:59, 21 February 2005

2005-02-21T14:59:43Z

New page

...hmm...shouldn't it be some text about customizing kernel here?
Did someone removed it?
I have looking for this article through out google for some time now...
Can someone please kindly post the article here?

^^ Thanks

@@ Line 18: / Line 18: @@
 The Linux kernel in Knoppix 3.1 (12/12/2002) is a vanilla 2.4.20 kernel with xfs and a patch included on the CD which extends the amount of boot parameters possible. The knoppix kernel patch also makes changes for the initial ramdisk, which I am not too sure of. What I am sure of is the kernel seems to expect an initrd image of a specific size, so any changes I have been successful with making have only been in a copy of the original miniroot image. I started with a vanilla 2.4.20 kernel as well, but it's possible the patch can be applied to a different kernel version, or to just read the patch file and apply the changes by hand. It's only about a six-line patch.
-[[Zug Schlus]] adds:
+Zug Schlus adds:
 The Linux Kernel in KNOPPIX 3.3 (2003-11-19) is a 2.4.22 with XFS patches. The command line buffer patch is included on the KNOPPIX CD in /usr/src and is the only patch that is really necessary. The later kernel seems to be able to cope with different miniroot sizes, as I have never had any problems with rebuilt miniroots.
@@ Line 29: / Line 29: @@
 == PREPARING YOUR DEVELOPMENT ENVIRONMENT ==
-[[Zug Schlus]] adds:
+Zug Schlus adds:
 The [[Knoppix Remastering Howto]] now contains a script that mounts and unmounts the boot floppy and the initrd image automatically. So you just need to invoke that script, and you're set to go without having to follow the detailed instructions below.
@@ Line 55: / Line 55: @@
 As linuxrc executes, it attempts to mount the base CD on /dev/hd'''1-99 and /dev/scd'''1-99, which means it has a pretty good chance of finding it. At this point the whole filesystem is still in ram, so the CD must first be mounted to get to the compressed /cdrom/KNOPPIX/KNOPPIX image file. Once the CD has been mounted, a second ramdisk is created with a dynamic size dependent on available and free memory which will be used for home directories and /var. Finally, cloop.o is loaded into the kernel and the compressed system image is mounted on /KNOPPIX, making all the symlinks work as part of the root filesystem. Next, more symlinks are created and important system files are copied to the ramdisk so they can be written to if need be. See the linuxrc script for specifics.
-[[Zug Schlus]] adds:
+Zug Schlus adds:
 KNOPPIX 3.3 supports the boot options "toram" and "tohd" which copies the cloop image to a RAM disk or to a physical disk, freeing the CD ROM drive in the process so that it can be used from KNOPPIX with other CDs. The linuxrc script in the miniroot takes care of that as well. The toram features needs at least a Gig of RAM, so it is most useful when used with a custom KNOPPIX version that has most of the packages removed. It is extremely handy to have a 50 MB text-only KNOPPIX as a rescue system that fits nicely on a business card CD. Just be sure to keep the ash package installed since linuxrc uses the presence of /KNOPPIX/bin/ash to determine whether this is a CD boot or a boot from a HD-installed KNOPPIX version.
@@ Line 67: / Line 67: @@
 Now that all your modifications have been made to the miniroot and boot image which contains it, you are safe to 'umount mroot' (unmount miniroot), 'gzip miniroot' (recompress it), 'rm -f boot/miniroot.gz' (delete the original from the boot image), and 'cp miniroot.gz boot' to replace it with your modified miniroot. Now you are free to edit the boot message in boot/boot.msg or any boot parameters in boot/syslinux.cfg. When you are done, just 'umount boot' and copy your new boot.img to master/KNOPPIX. You can still leave the original if you wish. The actual boot image the CD boots from is specified when you run mkisofs to create your new CD image.
-[[Zug Schlus]] adds:
+Zug Schlus adds:
 The script given in the [[Knoppix RemasteringHowto]] automatically re-builds the miniroot.gz after zeroing out the unused parts of the image. It will also automatically unmount both images and run syslinux on the new boot.img.

@@ Line 115: / Line 115: @@
 MB limit explained:
-  [http://syslinux.zytor.com/iso.php link ISOLINUX] explains why there is a 3MB limit (technically it's 2.88 mb) on the boot size. In short: A floppy can have a maximum size of 2.88 MB (if formatted accordingly). The El Torito standard allows booting from a CDROM by emulating a floppy or a hard drive. A floppy emulation must have an exact size. Some BIOSes (my guess is mostly older ones) do not support hard drive emulation. So if you want to avoid the 2.88 MB limit, use ISOLINUX. Depending on the age of your BIOS, this will work fine.
+  [http://syslinux.zytor.com/iso.php link ISOLINUX]
 Update explanation to apply to 3.6 and beyond. The quick notes listed are just that.

@@ Line 112: / Line 112: @@
 TODO
 Research miniroot a bit more and see what kernel mods may be necessary to change it's size. Creating one that is anything but the original 3MB seems to end badly for me.
 Update explanation to apply to 3.6 and beyond. The quick notes listed are just that.

@@ Line 76: / Line 76: @@
 In your master folder, create a folder called 'isolinux' and copy the contents of the boot image file (mounted in the boot folder) to master/isolinux. Now, all your boot files are easily accessed in the isolinux folder and you will not need to loop-mount a floppy image any more. It's good to keep a boot.img file somewhere on your CD though, in case somebody has trouble with isolinux. However, I have not seen any issues with isolinux on any relatively modern (or even older) hardware. Put isolinux.bin in the master/isolinux folder and remove ldlinux.sys. That's all you need to change as far as CD layout. Now the boot message and options can easily be tweaked without the constant mounting and unmounting of the floppy image.
-ISOLINUX can be downloaded from the syslinux package at [http://syslinux.zytor.com/iso.php.]  Using the latest versions the configuration file needs to be called isolinux.cfg not syslinux.cfg:
+ISOLINUX can be downloaded from the syslinux package at [http://syslinux.zytor.com/iso.php]  Using the latest versions the configuration file needs to be called isolinux.cfg not syslinux.cfg:
 mv isolinux/syslinux.cfg isolinux/isolinux.cfg
@@ Line 87: / Line 87: @@
 That's it! Now your boot environment is a bit easier to maintain, and your kernel can be any size you like. Now the only thing you have to mount with the loop device is miniroot when you need to change things in it. If you don't need the scsi modules, chances are you will only need to replace the cloop module after kernel replacements.
 == FINAL NOTES ==

@@ Line 30: / Line 30: @@
 [[Zug Schlus]] adds:
-The [[[Knoppix RemasteringHowto]]] now contains a script that mounts and unmounts the boot floppy and the initrd image automatically. So you just need to invoke that script, and you're set to go without having to follow the detailed instructions below.
+The [[Knoppix Remastering Howto]] now contains a script that mounts and unmounts the boot floppy and the initrd image automatically. So you just need to invoke that script, and you're set to go without having to follow the detailed instructions below.
 At this point you should already have Knoppix copied off of your CD and in source and master directories on a hard drive. In addition to making the source and master partitions (from now on I'll just call them source and master directories because I just made two directories on one partition: /mnt/hda1/source and /mnt/hda1/master.) you will also want to make two folders on the root of this partition: boot and mroot.  This will leave you with a partition having four folders: master, source, boot, and mroot. The first two you should already be familiar with. 'boot' will be where we will mount the boot.img file, and 'mroot' is where we will mount miniroot.gz, which is contained within the boot.img file. Are you with me so far? Good! Let's get started..
@@ Line 39: / Line 39: @@
 Now we have the boot floppy with the original kernel, miniroot.gz, and config files in the boot folder. I suggest copying any other files you wish to modify to the root of your dev partition as well, or maybe make a bak or tmp folder to store your backups in. From here on, I will just assume you are backing up all original files and not bug you any more about it. Just be aware of what exactly you have modified on your boot floppy, and don't forget to unmount it before copying it back to your master folder.
 == PREPARING YOUR KERNEL ==