Re: [GSoC] Remote kernel debugging over Ethernet

[George Georgalis <george%galis.org@localhost>]

On Wed 25 Mar 2009 at 05:38:11 PM -0400, Thor Lancelot Simon wrote:
>On Wed, Mar 25, 2009 at 11:01:21PM +0200, Jordan Gordeev wrote:
>>
>> One important question to ask is what the *goal* of kernel debugging  
>> over Ethernet is. There are virtualization solutions that can be used to  
>> debug a kernel without hangs and crashes. Some of them can offer access  
>> to kernel memory while the kernel is in a very "crashed" state. What  
>> can't be debugged with virtualization is only 1) device drivers for real  
>> hardware, and 2) SMP bugs that, due to timing, are only exhibited on  
>> real hardware.
>
>Unfortunately, these are pretty much the only cases in which I ever
>want a remote debugger of any kind -- otherwise, DDB suffices.
>
>That makes virtualization not-very-useful for solving the same problem
>a resuscitated IPKDB would solve.

Jordan- A few years ago (5?) FreeBSD supported remote kernel
debugging over firewire (don't think it's still supported). it was
really cool since firewire has direct DMA access. if some broken
code locked up the cpu, not only was debugging an option but the
firewire interface could be used to fix the problem, reset the cpu
and enable the host to continue operation. (maybe not for every
crash but I have seen the process demonstrated)

I don't know if there was any reason the 1394 debugger stopped
being supported but I suspect was just a matter of no maintainer
as freebsd went to 6.0.

Seems like an ideal interface for debugging since no software
is required on the remote host, not even a 1394 driver. This
is a newer revision of the presentation I saw:

http://www.lemis.com/grog/Papers/Debug-tutorial/tutorial.pdf

Since I see reference to freebsd 6 in the man pages... I wonder if
it is still supported there?

regards, George


-- 
George Georgalis <george%galis.org@localhost>, Information Systems <IXOYE><
SEEKING EMPLOYMENT OPPORTUNITIES, specialties: BSD/Linux, HPC,
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