[Lguest] Loading Lguest guest - Unhandled trap 256 at x100000

[Eviatar Khen]

You are wrong, the interrupt was not delivered to the guest because it in
invalid. An unhanded interrupt makes the host crash the guest.
It is hard to understand something from the screenshot. dSend to the
mailing list the config file and the system.map.


On Sat, Apr 27, 2013 at 1:04 AM, Naman Muley <naman.g.muley at gmail.com>wrote:

> Hey Eviatar,
>
> Thank you so much. I understand what i was doing.
> I've attached a screenshot of the disassembly. But i did not understand
> "it is very interesting to understand who generated it". how can you figure
> that out from the binary disassembly?
>
> Also, i did try read up on the unhandled trap, i found this:
> http://wiki.debian.org/Lguest
> and I understand why 256 is kind of odd because that interrupt number is
> not covered by the host and so we send it as a valid number to the guest.
> But the guest doesnt know how to handle this one.
> But i have no idea what is causing this and how to remove this.
>
> Any idea?
>
> Naman
>
>
> On Fri, Apr 26, 2013 at 4:33 PM, Eviatar Khen <eviatarkhen at gmail.com>wrote:
>
>>  Hi Naman,
>>
>> I think what Ron meant was to disassembly of the kernel's image
>> (vmlinux), not the Lguest binary (which is user space and does not generate
>> directly interrupts).
>> The guest crashes because the host got an invalid interrupt number, and
>> it is very interesting to understand who generated it.
>>
>> Good luck,
>>
>> Eviatar
>>
>>
>> On 04/26/2013 08:34 PM, Naman Muley wrote:
>>
>> Hey Ron,
>>
>>  Thanks for reaching out. I did the following( i am not sure if that's
>> what you wanted me to do) :
>>
>>  objdump -D -b binary -m i386 Documentation/virtual/lguest/lguest  >
>> /home/ngm7/disassembly.txt
>> Following is the screenshot: Does that make sense ?
>>
>>  I had to take a screenshot because the disassembly.txt is inside the
>> virtual machine. I'm working on ways to get that file out of the virtual
>> machine.
>>
>> NOTE: the last line in the file was 6a1d. In the meanwhile, if you want
>> to look at any specific line, let me know.
>> I apologize for the raw kind of feedback.
>>
>>  Naman
>>
>>
>>
>>
>> On Fri, Apr 26, 2013 at 11:45 AM, ron minnich <rminnich at gmail.com> wrote:
>>
>>> you might want to do a quick disassembly of the binary to see what's
>>> at 0x100000. The 256 is (to me) kind of odd. So what's the start of
>>> that image look like? Sorry, I'm rusty on lguest (i.e. I'm not Rusty)
>>> so I'm not going to be as useful. But I would be curious to see the
>>> disassembly.
>>>
>>> ron
>>>
>>
>>
>>
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>>
>>
>>
>
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