loader(8) not loading ?!? -> top not working

Giorgos Keramidas keramida at ceid.upatras.gr
Mon May 12 17:05:41 PDT 2003

On 2003-05-12 22:46, Thomas Weber <thomas at youngarts.org> wrote:
> Hi,
> yesterday i installed a new server with FreeBSD4.8-RELEASE. Unfortunately
> now top doesn't work, when i call it i get the error "top: nlist failed".
> I saw in the handbook, that this is happening if /boot/loader is not used
> for booting, "but doing it directily from boot2".

Actually it's the FAQ[1] that describes this in the "Troubleshooting"
section.  But this is not the whole story.  Not booting through
loader(8) is one of the two things listed there:

: 5.22. Why do I get the error ``nlist failed'' when running, for
: example, top or systat?
: The problem is that the application you are trying to run is looking
: for a specific kernel symbol, but, for whatever reason, cannot find
: it; this error stems from one of two problems:
:     * Your kernel and userland are not synchronized (i.e., you built a
:       new kernel but did not do an installworld, or vice versa), and
:       thus the symbol table is different from what the user
:       application thinks it is. If this is the case, simply complete
:       the upgrade process (see /usr/src/UPDATING for the correct
:       sequence).
:     * You are not using /boot/loader to load your kernel, but doing it
:       directly from boot2 (see boot(8)). While there is nothing wrong
:       with bypassing /boot/loader, it generally does a better job of
:       making the kernel symbols available to user applications.

Have you by any chance rebuilt & installed your kernel only lately?

> Uhm....... how can i change to loader(8)?

That depends on what this computer has installed, but in general you can
install the BootEasy loader using:

	# boot0cfg -v ad0


If you're running Windows NT, 2000 or XP I'm not sure if this is a good
idea.  These OSes tend to be rather picky and insist on using their
special "loader".  *ALWAYS* make sure you take backups of your MBR
before installing a new boot loader.

- Giorgos

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