Re: boot hd0a:/bsd.sp query

On 11/30/25 5:00 AM, Avon Robertson wrote:
> My home router hangs while booting /bsd.sp at the following line:
>
> root on sd0a (cd6f434607620efd.a) swap on sd0b dump on sd0b
>
> The router does not hang while booting if:
>
>>boot hd0a:/bsd.sp -c
> and then
> disable amdgpu
> is specified in UKC followed by
> quit
>
> However; as
>
> $ cat /etc/bsd.re-config
> disable amdgpu
>
> has been as above for 10 weeks and during that time /bsd has booted
> daily without errors occurring, my question is:
>
> what am I misunderstanding in the bsd.re-config(5) description below?
>
> DESCRIPTION
> The bsd.re-config file contains kernel modification commands in
> config(8) format. If present, it is used during system startup to
> configure the kernel that will be running at the next boot. It can
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> be used to enable or disable specific devices in the kernel.
>
> The router was sysupgrade'd -s this morning to:
>
> OpenBSD 7.8-current (GENERIC.MP) #127: Sat Nov 29 10:44:59 MST 2025
> deraadt@amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC.MP
>
> OpenBSD 7.8-current (GENERIC) #126: Sat Nov 29 10:32:29 MST 2025
> deraadt@amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC
>
> TIA for your input.
>

I do believe you understand the words a bit differently than intended.

Remember: OpenBSD relinks the kernel every boot. Sequence of events:
1) boot a kernel
2) kernel is running, multi-user, and in control of the hardware.
3) System startup takes place ... including
3a) daemons
3...)
3k) /bsd is relinked (KARL -- Kernel Address Randomization Link)
3...)
4) System is fully on-line and devoted to your tasks
5) ...time goes by, you do stuff...
6) you reboot
1) boot a kernel (relinked in step 3a above)

Now read the description again...
"If present, it is used during system startup [step 3!!] to configure the
kernel that will be running at the next boot [step 6 and later]"

So... your file impacts the NEXT /bsd that will boot...not the one
you happen to tell it to boot at the boot> prompt.
I suspect you (and I, initially) took "system startup" to mean "kernel
loading" -- no, kernel config is done during relinking, NOT during load,
and is part of the operation AFTER the system is multi-user, but not
before you can say it is finished starting.

BUT -- you aren't booting /bsd -- you override and booted /bsd.sp --
which a simple "ls -l /bsd*" will show you has NOT been modified:

$ ls -l /bsd*
-rwx------ 1 root wheel 32283298 Nov 22 01:03 /bsd*
-rwx------ 1 root wheel 32271586 Nov 21 23:42 /bsd.booted*
-rw------- 1 root wheel 4804509 Oct 13 08:07 /bsd.rd
-rwx------ 1 root wheel 32162643 Oct 13 08:07 /bsd.sp*
$ uptime
8:26PM up 8 days, 20:23, 3 users, load averages: 0.00, 0.01, 0.00


Though keep in mind, sometimes my role in life is to provide a wrong
answer so the smart people will have an opportunity to jump up and
down and point out how stupid I am, and provide the right answer. :)


As for your actual problem -- SOME video systems really don't like to
boot or run if a monitor is not attached. There are "cheater plugs"
("HDMI Dummy Plugs") made that will plug into an HDMI port and
convince the GPU a monitor is attached. Apparently, they are often
used in cryptomining, maybe AI, using GPUs as processors rather than
displays. Pretty cheap, under $10ea. I've got a few machines that
need these to do sysupdates, bsd.rd will not work without an attached
monitor, the full kernels will.

Nick.