Re: [PATCH v4] KVM: PPC: BOOKE: Emulate debug registers and exception

[Alexander Graf <agraf@suse.de>]

On 13.08.14 11:09, Bharat Bhushan wrote:
> This patch emulates debug registers and debug exception
> to support guest using debug resource. This enables running
> gdb/kgdb etc in guest.
> 
> On BOOKE architecture we cannot share debug resources between QEMU and
> guest because:
>     When QEMU is using debug resources then debug exception must
>     be always enabled. To achieve this we set MSR_DE and also set
>     MSRP_DEP so guest cannot change MSR_DE.
> 
>     When emulating debug resource for guest we want guest
>     to control MSR_DE (enable/disable debug interrupt on need).
> 
>     So above mentioned two configuration cannot be supported
>     at the same time. So the result is that we cannot share
>     debug resources between QEMU and Guest on BOOKE architecture.
> 
> In the current design QEMU gets priority over guest, this means that if
> QEMU is using debug resources then guest cannot use them and if guest is
> using debug resource then QEMU can overwrite them.
> 
> Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>

Scott, could you please recheck whether you're ok with it now? :)


Thanks,

Alex