From Newsgroup: muc.lists.freebsd.stable

Hi,

I got my first kernel panic in ten years! (Was attempting to add a 32nd zvol-backed drive to a bhyve guest.)

This host didn't have kernel debug symbols. I went to install them and discovered my host needed updates. Thoughtlessly, I grabbed the new
kernel and the new symbols.

Oops. You can't debug a 15.0 kernel on 15.0p3.

bucket/var/crash;kgdb -n 0
kgdb: couldn't find a suitable kernel image

I have a 15.0 boot environment I could boot into, if there's a way to
install the debugging symbols? Or is there a way to pull the old
kernel and debug symbols down on the current BE?

On dch's advice I tried setting the pkg.conf URL:
url: "pkg+https://cloudfront.aws.pkgbase.freebsd.org/FreeBSD:15:amd64/base_release_ 0/"
but got:
pkg: No SRV record found for the repo 'FreeBSD-base'


Thanks,
==ml

PS: I shoulda just done make world, that way I'd have /boot/kernel.old. ;-)
--
Michael W.(Warren) Lucas https://mwl.link/



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From Newsgroup: muc.lists.freebsd.stable

On Tue, Feb 17, 2026 at 12:37rC>PM Michael W. Lucas <mwl@mwl.io> wrote:

Hi,

I got my first kernel panic in ten years! (Was attempting to add a 32nd zvol-backed drive to a bhyve guest.)

This host didn't have kernel debug symbols. I went to install them and discovered my host needed updates. Thoughtlessly, I grabbed the new
kernel and the new symbols.

Oops. You can't debug a 15.0 kernel on 15.0p3.

bucket/var/crash;kgdb -n 0
kgdb: couldn't find a suitable kernel image

I have a 15.0 boot environment I could boot into, if there's a way to
install the debugging symbols? Or is there a way to pull the old
kernel and debug symbols down on the current BE?

On dch's advice I tried setting the pkg.conf URL:
url: "pkg+https://cloudfront.aws.pkgbase.freebsd.org/FreeBSD:15:amd64/base_release_
0/"
but got:
pkg: No SRV record found for the repo 'FreeBSD-base'

Thanks,
==ml

PS: I shoulda just done make world, that way I'd have /boot/kernel.old. ;-)

--
Michael W.(Warren) Lucas https://mwl.link/

You can probably install the symbols from the DVD image. They're in
the kernel-dbg.txz dist set. That should work for you, since your
crash happened in 15.0. But the same technique wouldn't work if you
had crashed at, say, 15.0-p1.
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From Newsgroup: muc.lists.freebsd.stable

On 2/17/26 11:37, Michael W. Lucas wrote:

Hi,

I got my first kernel panic in ten years! (Was attempting to add a 32nd zvol-backed drive to a bhyve guest.)

This host didn't have kernel debug symbols. I went to install them and discovered my host needed updates. Thoughtlessly, I grabbed the new
kernel and the new symbols.

Oops. You can't debug a 15.0 kernel on 15.0p3.

bucket/var/crash;kgdb -n 0
kgdb: couldn't find a suitable kernel image

I have a 15.0 boot environment I could boot into, if there's a way to
install the debugging symbols? Or is there a way to pull the old
kernel and debug symbols down on the current BE?

On dch's advice I tried setting the pkg.conf URL:
url: "pkg+https://cloudfront.aws.pkgbase.freebsd.org/FreeBSD:15:amd64/base_release_
0/"
but got:
pkg: No SRV record found for the repo 'FreeBSD-base'

Thanks,
==ml

PS: I shoulda just done make world, that way I'd have /boot/kernel.old. ;-)

Going in somewhat of a different direction, these days you should be
explicit about how the 15.0 kernel came to be in place for asking such questions:

) pkgbase (with what packages installed)?
) distribution sets (with which installed)?
) source build and install (with what built and installed)?

The proper activity to get symbols in place likely depends on such. If
pkgbase is involved, then there are more considerations related to
ending up failing its self checks if the system is modified via other
than pkg. Also pkgbase has a non-git /usr/src/ tree (if one has had it installed).

I've never seen anything explicit about how to deal with debugging for
pkgbase installs, much less for when symbols and/or source was not
installed up front.

Whatever the case for such, well identifying the installation technique
when asking questions is appropriate.
--
===
Mark Millard
marklmi at yahoo.com


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From Newsgroup: muc.lists.freebsd.stable

On Feb 18, 2026, at 4:17 AM, Colin Percival <cperciva@tarsnap.com> wrote:

On 2/17/26 11:41, Alan Somers wrote:

On Tue, Feb 17, 2026 at 12:37rC>PM Michael W. Lucas <mwl@mwl.io> wrote:

This host didn't have kernel debug symbols. I went to install them and
discovered my host needed updates. Thoughtlessly, I grabbed the new
kernel and the new symbols.

Oops. You can't debug a 15.0 kernel on 15.0p3.

bucket/var/crash;kgdb -n 0
kgdb: couldn't find a suitable kernel image

I have a 15.0 boot environment I could boot into, if there's a way to
install the debugging symbols? Or is there a way to pull the old
kernel and debug symbols down on the current BE?

On dch's advice I tried setting the pkg.conf URL:
url:
"pkg+https://cloudfront.aws.pkgbase.freebsd.org/FreeBSD:15:amd64/base_release_
0/"
but got:
pkg: No SRV record found for the repo 'FreeBSD-base'

That isn't going to work because pkg+https says "look up SRV records" and the cloudfront.aws.pkgbase.freebsd.org endpoint is *what the SRV record points at*. You could have used pkg+https://pkg.freebsd.org/, but that wasn't going to work anyway since the repo will give you the latest packages (aka the -p3 kernel).

The older packages are actually still there, but there's no way for you to find them.

You can probably install the symbols from the DVD image. They're in
the kernel-dbg.txz dist set. That should work for you, since your
crash happened in 15.0. But the same technique wouldn't work if you
had crashed at, say, 15.0-p1.

The DVD image is the way to go. Either from kernel-dbg.txz or from the pkgbase repo on the DVD image. But as Alan notes, this only works because you crashed on the original release.

We should probably consider creating a separate stash of kernel debug packages
,about this until now.c
Oh, a third option is to boot up an EC2 15.0-RELEASE-p1 image ("base" or "cloud-init"; "small" doesn't have debug symbols). But I'm guessing you'd prefer to look at your panic locally.

I keep all ZFS snapshots of old releases, and retrieve the old kernel and debug symbols
from them.
Often users report issues with old releases and developers have limited bandwidth and
probably have newer release while looking into the issue.
I sometime wonder if it is possible to install a base version into a jail, then update it to
required patched version? Say install 14.3-RELEASE, and update to 14.3-RELEASE-p1 ?

--
Colin Percival
FreeBSD Release Engineering Lead & EC2 platform maintainer
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid

Best regards,
Zhenlei
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