Where is vmlinuz actually

Where is vmlinuz actually

Post by Robin Becke » Thu, 03 Oct 1996 04:00:00



Having accidentally moved vmlinuz to another filesystem I expected my
system to fail to boot even though I moved vmlinuz back to root. The
system continues to boot ok though. I'm using a simple multiple boot
sector based (I think) on an old DOS multiboot. I use lilo to install it
when I upgrade the kernel.
How is it that the system remains ok & will it remain so?
--
Robin Becker

 
 
 

Where is vmlinuz actually

Post by Neil Ricke » Thu, 03 Oct 1996 04:00:00



Quote:>Having accidentally moved vmlinuz to another filesystem I expected my
>system to fail to boot even though I moved vmlinuz back to root. The
>system continues to boot ok though. I'm using a simple multiple boot
>sector based (I think) on an old DOS multiboot. I use lilo to install it
>when I upgrade the kernel.
>How is it that the system remains ok & will it remain so?

When you moved vmlinuz, the old sectors were freed, but retained
their old contents.  Until those sectors are reused with new data, it
will boot.  Best rerun lilo, so it points to the current copy.

vmlinuz can actually be anywhere.  But you should either put a
symlink to in in '/', or change lilo.conf to have the correct path.
And then rerun '/sbin/lilo' whenever you move it, so that the boot
info correctly maps the sectors used for the kernel.

 
 
 

Where is vmlinuz actually

Post by Geoff Sho » Fri, 04 Oct 1996 04:00:00


: Having accidentally moved vmlinuz to another filesystem I expected my
: system to fail to boot even though I moved vmlinuz back to root. The
: system continues to boot ok though. I'm using a simple multiple boot
: sector based (I think) on an old DOS multiboot. I use lilo to install it
: when I upgrade the kernel.
: How is it that the system remains ok & will it remain so?

Lilo uses the physical location of vmlinuz on the disk to boot - so
renaming it, moving it to a different directory etc. will not make any
difference.  If you have deleted it from the disk, then that part of the
disk will become overwritten with time, and the boot will fail.  Also, when
you reinstall lilo, it won't find vmlinuz in /.

        Geoff
--
----------------------------------------------------------------------------


can't identify with that kind of work ethic. http://kipper.york.ac.uk/~geoff

 
 
 

Where is vmlinuz actually

Post by Robin Becke » Fri, 04 Oct 1996 04:00:00





>: Having accidentally moved vmlinuz to another filesystem I expected my
>: system to fail to boot even though I moved vmlinuz back to root. The
>: system continues to boot ok though. I'm using a simple multiple boot
>: sector based (I think) on an old DOS multiboot. I use lilo to install it
>: when I upgrade the kernel.
>: How is it that the system remains ok & will it remain so?

>Lilo uses the physical location of vmlinuz on the disk to boot - so
>renaming it, moving it to a different directory etc. will not make any
>difference.  If you have deleted it from the disk, then that part of the
>disk will become overwritten with time, and the boot will fail.  Also, when
>you reinstall lilo, it won't find vmlinuz in /.

>       Geoff
>--
>----------------------------------------------------------------------------


>can't identify with that kind of work ethic. http://kipper.york.ac.uk/~geoff

Actually as Robert Nicholls has already told me moving to another FS
doesn't neccessarily cause an immediate crash. This was what I was
observing. It took me 8 reboots to eventually find a nonbootable system.
As he points out
Quote:>The boot loader is still reading the old data in the disk sectors
>occupied by the old vmlinuz.  Those sectors are currently marked "free"
>in the file system.  When some of that space gets overwritten by a new
>file, you will be unable to boot.  I suggest that you re-run the Lilo
>installer before that happens.

Luckily I was aware of the situation and knew what was going on. The
real danger is that each time I rebooted and the system came up the disk
sectors could have contained partially valid data; since I use a
compressed kernel it's unlikely to decompress with bad data, but all
things are possible and a successful decompression would lead to a
highly unstable system which could do anything.
--
Robin Becker
 
 
 

Where is vmlinuz actually

Post by Robin Becke » Sat, 05 Oct 1996 04:00:00





>zum Thema "Re: Where is vmlinuz actually":


>> : Having accidentally moved vmlinuz to another filesystem I
>> expected my : system to fail to boot even though I moved vmlinuz
>> back to root. The : system continues to boot ok though. I'm using a
>> simple multiple boot : sector based (I think) on an old DOS
>> multiboot. I use lilo to install it : when I upgrade the kernel.
>> : How is it that the system remains ok & will it remain so?

>> Lilo uses the physical location of vmlinuz on the disk to boot - so
>> renaming it, moving it to a different directory etc. will not make
>> any difference.  If you have deleted it from the disk, then that
>> part of the disk will become overwritten with time, and the boot
>                          ^^^^^^^^^^^^^^^^^^^^^^^^^^!!!!

>Please pay your consideration to this VERY crucial point!

>In fact, you made my hair stand on end, when I read your posting.... ;-)

>Obviously, what you say, is perfectly correct.

>But please remember, here are beginners and newbies with us.

>And it is the best advice, never to be thoughtless with the
>location or the name of vmlinux.

>Even the following:

>> will fail.  Also, when you reinstall lilo, it won't find vmlinuz in
>> /.

>will lead to big problems.

>And: Moving vmlinuz to a different directory can lead to desastrous
>consequences, if this directory resides on another filesystem, even
>on the same disk. In this case, it would be not only the redirection
>of the physical link, but even more the file itself would be moved to
>another partition.

>Booting the first time after this operation may work, by chance.

>But at last, it will not be possible to reboot the system, and
>unexperienced users will get into great trouble.

>So, please be _very_ careful discussing those details, and always
>remember: There is only one thing, which is better than having
>a working bootdisk for Linux: To have two working bootdisks for
>Linux.

>Myself, I have two complete rootfilesystems on hard disk and a
>special boot configuration for new kernels which is based
>on a symbolic link /neu.kernel which is linked against
>/usr/src/linux/arch/i386/boot/bzImage. Thus, I can rerun lilo
>and test the new kernel after having recompiled my kernel and
>if I'm satisfied after a few tests, I copy my new kernel
>to the old one without destroying my test configuration.

>Thus I have always two working rootfilesystems and at least one,
>mostly two bootable kernels on hard disk.

>Regards

>Detlef

>--

>Bienroder Weg 79                                Tel.: +49 531 303383
>                                                D2:   +49 172 5208778
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>         >>>> PGP Public Key als Empfangsbestaetigung <<<<
>## CrossPoint v3.1 R ##

I agree completely which is why I posted originally. Seems real
dangerous that my system could boot 8 times without crashing & then
boom! Enschuldigen Sie mich bitte mea culpa.
--
Robin Becker
 
 
 

Where is vmlinuz actually

Post by Cornwall Business Cente » Sat, 12 Oct 1996 04:00:00


Hi Robin


Quote:> Having accidentally moved vmlinuz to another filesystem I expected my
> system to fail to boot even though I moved vmlinuz back to root. The
> system continues to boot ok though. I'm using a simple multiple boot
[snip]...
> How is it that the system remains ok & will it remain so?

As long as LILO knows which root of which device vmlinuz is found, the
system will boot no matter what.

Remember this isn't DOS we're talkin' about here ;)

Later...        Mike

 
 
 

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says...

I admire your passion, Chris..

The only issues which have kept myself from looking seriously at Linux
would be:

* It's Unix and the learning curve to start getting productive strikes me
as probably very steep

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--
Reuben King
Email: "reuben at texas dot net" (in plain english to foil spam-bots.
grrr!)

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