[Qemu-devel] Debugging on HAXM

[Alexandro Sanchez Bach]

Hello,

 

A bit of context: I'm working on a QEMU fork adding support for PlayStation
4 hardware. It's still in development and debugging kernel drivers has
become everyday work. While TCG supports debugging, it cannot handle various
extensions like AVX/AVX2 that are extensively used by the guest applications
and performance has become quite a problem. This system is closed source and
wasn't built with kernel debugging support, so debugging it "from the
outside" is the only possibility and hence why debugging on accelerators
(specially HAXM/WHPX) has become absolutely necessary for my project.

 

I've noticed that `gdb_breakpoint_insert` only considers KVM so far. My
question is: Has anyone planned adding debugging support to HAXM? Or is
anyone actively working on QEMU's HAXM frontend at all? If not, I would like
to work on it myself. Are there any guidelines or things I should take into
consideration to work on this accelerator (pinging Anthony and Glauber)?
Would it be more reasonable to add debugging support to HAXM [1] directly
instead of trying to use the existing APIs from QEMU to achieve the same
thing  (I was thinking in patching memory, e.g. with `hlt` instructions, to
trigger VM exits)?

 

Just want to hear your thoughts on the matter. :-)

 

Cheers,

Alexandro Sanchez

 

[1] https://github.com/intel/haxm/