Re: Loading splash ok -> <reset>, how to debug?

On Sun, 8 Jun 2025, Warner Losh wrote:

> On Sun, Jun 8, 2025 at 11:46 AM Bjoern A. Zeeb
> <[email protected]> wrote:
>>
>> On Sun, 8 Jun 2025, Warner Losh wrote:
>>
>>> On Sun, Jun 8, 2025, 10:08 AM Tomek CEDRO <[email protected]> wrote:
>>>
>>>> On Sun, Jun 8, 2025 at 5:10 PM Bjoern A. Zeeb
>>>> <[email protected]> wrote:
>>>>> Hi,
>>>>> is there any good way to debug early kernel kabooms (or maybe efi loader
>>>>> handover) without JTAG in place?
>>>>> I have a SoC using U-Boot and often after a cold start it goes like
>>>>> this:
>>>>> ------------------------------------------------------------------------
>>>>> Hit [Enter] to boot immediately, or any other key for command prompt.
>>>>> Booting [/boot/kernel/kernel]...
>>>>> Using DTB provided by EFI at 0x3e6c3000.
>>>>> Loading splash ok
>>>>> <reset>
>>>>> ------------------------------------------------------------------------
>>>>> Once it's been looping for a few iterations eventually it starts
>>>>> booting.
>>>>> Given there is zero output of the error, is there aything one could try
>>>>> to do to debug this (remotely)?
>>>>> I can netboot it and change laoder/kernel.
>>>>
>>>> DDB?
>>>> https://docs.freebsd.org/en/books/developers-handbook/kerneldebug/#kerneldebug-online-ddb
>>>>
>>>> KGDB?
>>>> https://docs.freebsd.org/en/books/developers-handbook/kerneldebug/#kerneldebug-online-gdb
>>>>
>>>> over the Serial Port? :-)
>>>>
>>>
>>> I think he's not even getting to the handoff. Best to toss out all
>>
>> hmm..
>>
>>> graphical things that are configured and see if that gets us to the handoff
>>> point... get rid of the splash screen first of all..
>>
>> How?  I do not have boot_mute="YES" set.
>
> By not configuring the splash screen. We wouldn't be loading it if it
> wasn't configured.

Then it's done because it's in defaults/loader.conf ?

I set splash="" now, which seems to make a difference;  magic not
working correctly enabling it automatically?


>> I tried setting console to just efi manually; that didn't help. Also on
>> first attempt I got an error, typing it again worked (but I didn't
>> re-validate).
>
> OK. efi is the default console, so it's not surprising it didn't
> change anything.
>
>> I have the following in loader.conf and I tried various combinations without
>> success to see ... I also tried to fdt ls to make sure fdt is all right
>> and there...
>>
>> ----------------------------------------
>> boot_verbose="-v"
>> debug.kdb.alt_break_to_debugger=1
>> beastie_disable="YES"
>> ----------------------------------------
>>
>> Do we have a way to validate in loader if a kernel loaded into memory is
>> correct?  I was wondering if the kernel was corrupted...
>
> It's not. Or rather, the data you've given doesn't show the kernel
> loading in the detail that should be there. But yea, if the kernel is
> corrupt, all bets are off.
>
> Can you just post the entire log from when the boot loader starts to
> the error? That will end all ambiguity.

Had to hard reset it;  with splash="" the error seems to have shifted:

------------------------------------------------------------------------
Consoles: EFI console
     Reading loader env vars from /efi/freebsd/loader.env
FreeBSD/arm64 EFI loader, Revision 3.0
(Thu Jun  5 10:57:09 UTC 2025 bz@somearm64)

    Command line arguments: loader.efi
    Image base: 0x3e5ee000
    EFI version: 2.110
    EFI Firmware: Das U-Boot (rev 8229.1024)
    Console: efi,comconsole (0)
    Load Path: /\exports\foo01\boot\loader.efi
    Load Device: ...
    BootOrder: 0000
Setting currdev to net0:


cLoading kernel...
/boot/kernel/kernel text=0x318 text=0x9be4e8 text=0x2d7260 data=0x181168 data=0x0+0x371000 0x8+0x1721a0+0x8+0x1a2cf5-
Loading configured modules...
can't find '/boot/entropy'
can't find '/etc/hostid'

Hit [Enter] to boot immediately, or any other key for command prompt.
Booting [/boot/kernel/kernel] in 9 seconds...


Using DTB provided by EFI at 0x3e6c3000.
\
------------------------------------------------------------------------


-- 
Bjoern A. Zeeb                                                     r15:7