Re: What do you use for kernel debugging?

On 9/29/14, 9:35 AM, Garrett Cooper wrote:
>> On Sep 28, 2014, at 17:51, "José Pérez Arauzo" <fbl_at_aoek.com> wrote:
>>
>> Hi Benjamin,
>>
>> On Sun, 28 Sep 2014 15:54:36 -0400 (EDT), Benjamin Kaduk wrote
>>> On Sun, 28 Sep 2014, José Pérez Arauzo wrote:
>>>
>>>> Hello,
>>>> I am trying to track down a (deadlock?) issue in CURRENT via DDB. The
>> kernel does
>>>> not complete hw probes on my Acer V5.
>>>>
>>>> I get stuck on apic_isr looping which leads nowhere.
>>>>
>>>> So I thought maybe things improve if I debug from another machine.
>>>>
>>>>
>>>> What do you use for kernel debugging? According to the handbook kgdb over
>> serial
>>>> is a good option, do you agree? I'm on a netbook with no ethernet and no
>> option
>>>> for firewire: can I have a USB / nullmodem setup to work?

with hardware related debugging it's always hard.. in the past I used 
serial and firewire
but they are getting hard to find.

if it wasn't hardware related then using bhyve with it's gdb debugger 
hook works fine.

Unfortunately you can't use a USB serial as it requires the USB stack 
be  working before it can be used..
similar with ethernet connected debugging which requires that the 
driver for the ethernet hardware support it.
(which why we don't have it in the tree though it has been done 
several times in the past).


>>> You cannot.
>> Oh, what a shame. Why not? Is it because you need hardware probe to
>> be over to use it?
>>
>> Today I bought a shining USB to USB thingy made by Hama, and guess what?
>> It's not supported on FBDS, altought uplcom(4) reports support for
>> Hama USB to RS232 brother.
> The bootloader doesn't support USB debugging and I'm pretty sure the devices don't support local/remote debugging :(.. I'll do some poking around. I'll talk to some SMEs and see if I can write up a TODO list for a wiki page.
>
> Cheers!
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