Re: [Qemu-arm] [PATCH v1 0/2] Fix kvm guest debugging of AA32 guests on AA64

[Mark Rutland]

Hi Alex,

On Thu, Dec 13, 2018 at 11:55:01AM +0000, Alex Bennée wrote:
> Hi,
> 
> This is an attempt to fix debugging of AArch32 binaries when running
> under KVM on AArch64 hardware. There are two parts to this, the first is
> a handling the possibility of AArch32 software breakpoints with a
> heuristic based on the current execution mode. The second part is
> delaying the setup of aarch64 debugging until the shared arm_cpu_realize
> function is run by which point we have parsed and decoded the actual
> execution mode of the guest. This doesn't solve the problem of split
> mode guests which switch between an AA64 EL1 and an AA32 EL0 though.
> 
> I still ran into a problem with single-step. Even with Mark's
> single-step fixup series:
> 
>   To: address@hidden
>   Cc: address@hidden,
>   Subject: [PATCH 0/2] kvm/arm: make singlestep behaviour consistent
>   Date: Fri, 9 Nov 2018 15:07:09 +0000
>   Message-Id: <address@hidden>
> 
> some instructions do single-step but sometimes the single-step doesn't
> return leading to a runaway until it hits a breakpoint. I'm not sure why
> this is the case because the SS state machine shouldn't be instruction
> sensitive.

Could you please give an example sequence where this occurs? I'd be
happy to take a look.

Thanks,
Mark.