Re: [Qemu-discuss] Incomplete '-d exec' traces?

[Evan Driscoll]

On 01/09/2015 06:03 PM, Peter Maydell wrote:
> You're likely seeing the results of QEMU's TB chaining optimization.
> Basically, if a jump target (or conditional jump target) is to a
> known TB that we have already translated, we will patch it so that
> we jump directly from one TB to the next without coming back out
> to the inner loop. When we do this we won't log the execution of
> the second and subsequent TBs in a chain, because the logging happens
> in the cpu-exec loop.
>
> You can check whether this is the issue by commenting out the call
> to tb_add_jump() in cpu-exec.c, which will disable the optimization.
That appears to be it. Thank you very much!

Evan



> (I did at one point have some patches that logged the creation of the
> chains (which would let you reconstruct execution from the log) but
> they were a bit hacky because they didn't log when we unlinked a
> chain again.)
>
> -- PMM