Re: [Qemu-devel] [RFC PATCH 00/17] reverse debugging

[Ciro Santilli]

On Sat, Apr 28, 2018 at 10:27 AM, Pavel Dovgalyuk <address@hidden> wrote:
>
>
>> -----Original Message-----
>> From: Ciro Santilli [mailto:address@hidden
>> Sent: Saturday, April 28, 2018 11:13 AM
>> To: Pavel Dovgalyuk
>> Subject: Re: [RFC PATCH 00/17] reverse debugging
>>
>> Forgetting about debugging, I belive there is a deadlock in the replay
>> at 63d426dfa4fbfac3d50cda3f553cd975de2b85ea , but it is rare.
>>
>> I have only reproduced it on ARM so far, and I haven't checked pre-patch.
>>
>> The setup is https://github.com/cirosantilli/qemu-
>> test/tree/6a3497f0d84e7c86ef80f7322e24e8a149b93214
>> with images-ab21ef58deed8536bc159c2afd680a4fabd68510.zip
>>
>> Then try to run it several times with:
>>
>> i=0; while true; do date; echo $i; ../qemu-test/arm/rr; i=$(($i+1)); done
>>
>> I think the deadlock can happen in a few different places, but the
>> most common is when the kernel is doing disk related stuff, the last
>> messages before getting stuck are:
>
> It usually happens when there is some bugs in the implementation of the 
> virtual devices.
> Our customers mostly emulates x86-based systems, therefore most of
> the ARM hardware is untested.
>

Hi Pete, do you know anything about this? Traces at:
http://lists.nongnu.org/archive/html/qemu-devel/2018-04/msg05218.html
command at: 
https://github.com/cirosantilli/qemu-test/blob/6a3497f0d84e7c86ef80f7322e24e8a149b93214/arm/rr

@Pavel: I recommend always replying to both me and to qemu-devel to
preserve a better history of our talk on the tracker.

>> [   11.530325] ALSA device list:
>> [   11.531451]   No soundcards found.
>>
>> and what would follow on a normal replay would be:
>>
>> [   11.551904] EXT4-fs (vda): couldn't mount as ext3 due to feature
>> incompatibilities
>> [   11.619238] EXT4-fs (vda): mounted filesystem without journal. Opts: 
>> (null)
>>
>> I then attach GDB with:
>>
>> gdb -q ./arm-softmmu/qemu-system-arm `pgrep qemu`
>
>
>
>
> Pavel Dovgalyuk
>