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Date:      Fri, 24 Dec 2021 16:31:29 +0100
From:      "Julian H. Stacey" <jhs@berklix.com>
To:        Kyle Evans <kevans@freebsd.org>
Cc:        "freebsd-hackers@freebsd.org" <hackers@freebsd.org>
Subject:   Re: /boot/loader.conf debuging traces come out jumbled
Message-ID:  <202112241531.1BOFVTKv003800@fire.js.berklix.net>
In-Reply-To: Your message "Mon, 13 Dec 2021 18:17:52 -0600." <CACNAnaHiWfMOv35EPJoGsAv%2B93ymdS_wNyyKpQ_Y=YsMBtZUcg@mail.gmail.com>

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Hi, Reference:
> From:		Kyle Evans <kevans@freebsd.org>
> Date:		Mon, 13 Dec 2021 18:17:52 -0600

Kyle Evans wrote:
> On Mon, Dec 13, 2021 at 6:07 PM Julian H. Stacey <jhs@berklix.com> wrote=
:
> >
> > Debugging my /boot/loader.conf on 12.2-STABLE (with a 12.2-RELEASE ker=
nel,
> >
> >   (as 12.2-STABLE & 12.3-RELEASE & 13.0-RELEASE GENERIC kernels crash =
during
> >    boot on one machine here (To be subject of later analysis &
> >    posting)...  I got distracted onto debugging boot options, after
> >    output from booting screen rolled off the top), So I concentrated
> >    first on identifying & hashing out noisey boot options , before
> >    next searching how to capture boot text (maybe to a serial port ?) =
)
> >
> > I tried adding markers to loader.conf create deliberate visible error =
texts to
> > mark around lines I wanted to study the effect of, eg
> > fuse_load=3D"YES" etc ...
> >
> > I added this in the middle of /boot/loader.conf :
> >         ZZZZZZZZZ00000000_load=3D"YES"
> >         ZZZZZZZZZ00001111_load=3D"YES"
> >         ZZZZZZZZZ00002222_load=3D"YES"
> >         ZZZZZZZZZ44440000_load=3D"YES"
> >         ZZZZZZZZZ44441111_load=3D"YES"
> >         ZZZZZZZZZ44442222_load=3D"YES"
> >
> > & next boot showed a weirdly disordered:
> >
> >         Loading configured modules...
> >         can't find 'ZZZZZZZZZ00000000_load'
> >         can't find 'ZZZZZZZZZ00002222_load'
> >         can't find 'ZZZZZZZZZ44442222_load'
> >         can't find 'ZZZZZZZZZ44440000_load'
> >         can't find 'ZZZZZZZZZ44441111_load'
> >         can't find 'ZZZZZZZZZ00001111_load'
> >         /etc/hostid size=3D0x25
> >
> > its not even just a reverse order that one might have expected from
> > a forth unstacker or some such. Makes it harder to trace what output
> > lines come from which loader.conf lines.
> >
>
> To my knowledge, we've never guaranteed module load order beyond
> kernel-first then everything else. You'll have a much better time with
> _before/_after though; something like this should work:
>
> hostid_before=3D"echo before hostid"
> hostid_after=3D"echo after hostid"

Thanks Kyle for your _before & _after, it set me on course,
though there's no hostid_load=3D in 12.2 src/, these worked:
	usb_quirk_load=3D"YES"
	usb_quirk_before=3D"echo Before usb_quirk"
	usb_quirk_after=3D"echo After usb_quirk"

& I found lots of useful debugging stuff in /boot/defaults/loader.conf
& man loader.conf loader boot.  My next use will be boot -p or
boot_pause=3D""       # -p: Pause after each line during device probing

& then maybe some of:
#boot_ddb=3D""        # -d: Instructs the kernel to start in the DDB debug=
ger
#boot_gdb=3D""        # -g: Selects gdb-remote mode for the kernel debugge=
r
#boot_multicons=3D""  # -D: Use multiple consoles
#boot_serial=3D""     # -h: Use serial console
#boot_verbose=3D""    # -v: Causes extra debugging information to be print=
ed
#debug.kdb.break_to_debugger=3D"0" # Allow console to break into debugger.

Looking forward to debugging now screen doesnt roll off :-)

Cheers,
-- =

Julian Stacey  http://berklix.com/jhs/  http://stolenvotes.uk
Reduce contacts, vax & pass insufficient.   Dump UK's prime liar.



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