Re: [Qemu-devel] [PATCH v14 00/21] Deterministic replay core

[Paolo Bonzini <pbonzini@redhat.com>]

On 25/05/2015 14:07, Pavel Dovgalyuk wrote:
> This set of patches is related to the reverse execution and deterministic 
> replay of qemu execution. This implementation of deterministic replay can 
> be used for deterministic debugging of guest code through gdb remote
> interface.
> 
> Core set of patches does not include support for reverse debugging commands
> of gdb, block devices' operations, USB replay support.
> 
> These patches include only core function of the replay,
> excluding the support for replaying serial, audio, network, and USB devices'
> operations. Reverse debugging and monitor commands were also excluded to
> be submitted later as separate patches.
> 
> Execution recording writes non-deterministic events log, which can be later 
> used for replaying the execution anywhere and for unlimited number of times. 
> It also supports checkpointing for faster rewinding during reverse debugging. 
> Execution replaying reads the log and replays all non-deterministic events 
> including external input, hardware clocks, and interrupts.
> 
> Full version of deterministic replay has the following features:
>  * Deterministically replays whole system execution and all contents of the memory,
>    state of the hadrware devices, clocks, and screen of the VM.
>  * Writes execution log into the file for latter replaying for multiple times 
>    on different machines.
>  * Supports i386, x86_64, and ARM hardware platforms.
>  * Performs deterministic replay of all operations with keyboard and mouse
>    input devices.
>  * Supports auto-checkpointing for convenient reverse debugging.
> 
> Usage of the record/replay core:
>  * First, record the execution, by adding the following string to the command line:
>    '-icount shift=7,rr=record,rrfile=replay.bin -net none'. 
>    Block devices' images are not actually changed in the recording mode, 
>    because all of the changes are written to the temporary overlay file.
>  * Then you can replay it for the multiple times by using another command
>    line option: '-icount shift=7,rr=replay,rrfile=replay.bin -net none'
>  * '-net none' option should also be specified if network replay patches
>    are not applied.
>  * Do not add any disk images to VM, because they are not supported by
>    the core patches.

Hi Pavel,

this series has reached a point where I need help from other
maintainers, particularly (but not exclusively) regarding their own
code.  I don't see anything that stands out (that's why I asked you to
remove the disks part), but it's a huge change and I don't feel
comfortable "just including it" in a pull request like I did with all
the preparatory changes so far.

Thanks for your understanding!

Paolo