Chapter 3. After LFS ... Issues - Creating a custom bootdisk

James Robertson jameswrobertson at
Fri Jun 13 05:20:06 PDT 2003

Bill's LFS Login wrote:
> Folks,
> Just remade my custom bootdisk using the 20030603 CVS book. I don't use
> devfs, so I don't know if this applies. But since I have some experience
> with booting, I thought I would mention this, and make an offer too.

I saw that hint come up.  I did not read the whole thing, but it looks good.

> The command "rdev /dev/floppy/0 /dev/floppy/0" seems to me to not do the
> right thing. The first "/dev/floppy/0" is correct, I guess. On my system
> I use "/dev/fd0", the normal /dev entry in a non-devfs system. But the
> second entry says to set the root device to the floppy, IIRC. Since the
> floppy in the drive at that time is not a file system, it should not
> work, if I understand these things correctly. But if I specify 0,0 in
> place of the second floppy specification, the root device defaults to
> the ram disk just loaded. This is as it should be, again, if my under-
> standing is correct.

I am not sure either here.  I am not a devfs user either.

> Tested and works *just fine*. BTW, this is with a 2.4.20 kernel, which I
> know has changed the boot process slightly since 2.4.18.
> Now, as to my offer. I'm thinking two things. First, since LFS default
> build is a "static" /dev directory, I think we should offer a few
> commands for that scenario. If there is agreement that it should be
> included, I'll be glad to cobble something together and sub some patched
> sections for y'all to peruse and include if appropriate.

I would agree here.  The more LFS teaches the better.

> A couple last notes. It seems to me that it is rediculous for LFS to
> help one create a basic platform without some kind of backup/recovery
> tool - especially one as basic and critical as a recovery or boot
> floppy. I feel strongly that we should lobby to get a basic boot
> diskette into LFS book. Am I off base? Is it worth bringing that up on
> the LFS dev list? I really don't feel like using a lot of bandwidth just
> to start a thread that may be known doomed to failure at the outset.

I agree here to.  There are no many n00bs on the support list now.  Many
don't take the time to read a lot of the pre-reading sugessted in the
book.  Most don't even look at the FAQ first!

> Another suggestion is that we tell the user to make an edited fstab (and
> any other files that will vary from what's on their box) *before* copying
> it to the new FS. The process of editing "in place" will cause some
> additional i-nodes to become non-zero and leave some "holes" in the FS
> that will reduce compression ratio, albeit slightly. Every little bit
> helps.
> Along the line of space, mention that in most case 2000 i-nodes will be
> excessive. I used 1600, still have about 400 or so left and gained about
> 45K, IIRC, of additional free space. That's enough room for 1.5 mke2fs
> binaries. By playing with that value, a *substantial* amount of space can
> be made available. Of course, when compression of binaries is
> considered, the gain on the initrd is not as substantial as we might
> like, but every little bit...
> Last, I think the addition of some verbiage about including an
> appropriate *fsck capability on the diskette should be included. I know
> this requires the recompilation of, for instance, e2fsck to be
> re-installed dynamically (possibly just for the diskette) so it can fit,
> but what good is a nice floppy if you can't at least run fsck on your
> FS? Further, a mk*fs should be recommend along the same lines. You might
> have great backups of partitions/data, but if you can't make an FS,
> and your FS is *gone*, what's the point of the backup? This is
> especially on my mind as I just finished my first hint contribution
> (booting related) and, while thinking critically about what to include,
> realized that between LFS and BLFS, very little direction/suggestion
> about these issues are given to the rapidly growing (and
> less-experienced?) community.
> I know that one valid response is that anybody that has progressed to
> the point of BLFS should be aware of, and know how to do, these things.
> But if you watch the lists, you will see that many people move quickly
> from LFS to BLFS without the background to even be aware of these basic
> issues. My feeling is that giving a point in the right direction, beyond
> just "copy any other binaries and libraries you need..." would be a
> useful expenditure of time.
> What'chall think?

As noted above, I think some steps to create a book disk are a good
idea.  I would place them near the end of the book, in the wrap up
section.  All the distros have a function to create a bookdisk during
their installers.  I don't see why LFS should not have a good boot disk
as well.

James Robertson | jameswrobertson at
Reg. Linux User: #160424
Reg. LFS User:   #6981

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