From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Graf Subject: Re: [PATCH v4] KVM: PPC: BOOKE: Emulate debug registers and exception Date: Wed, 27 Aug 2014 13:23:13 +0200 Message-ID: <53FDBFA1.2060509@suse.de> References: <1407920984-27555-1-git-send-email-Bharat.Bhushan@freescale.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, scottwood@freescale.com, stuart.yoder@freescale.com To: Bharat Bhushan , kvm-ppc@vger.kernel.org Return-path: In-Reply-To: <1407920984-27555-1-git-send-email-Bharat.Bhushan@freescale.com> Sender: kvm-ppc-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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 Scott, could you please recheck whether you're ok with it now? :) Thanks, Alex