From: Scott Wood <scottwood@freescale.com>
To: Alexander Graf <agraf@suse.de>
Cc: Bharat Bhushan <Bharat.Bhushan@freescale.com>,
<kvm-ppc@vger.kernel.org>, <kvm@vger.kernel.org>,
<stuart.yoder@freescale.com>
Subject: Re: [PATCH v4] KVM: PPC: BOOKE: Emulate debug registers and exception
Date: Wed, 27 Aug 2014 21:30:53 -0500 [thread overview]
Message-ID: <1409193053.6510.155.camel@snotra.buserror.net> (raw)
In-Reply-To: <53FDBFA1.2060509@suse.de>
On Wed, 2014-08-27 at 13:23 +0200, Alexander Graf wrote:
>
> 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? :)
I'm OK with it.
-Scott
next prev parent reply other threads:[~2014-08-28 2:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-13 9:09 [PATCH v4] KVM: PPC: BOOKE: Emulate debug registers and exception Bharat Bhushan
2014-08-27 11:23 ` Alexander Graf
2014-08-28 2:30 ` Scott Wood [this message]
2014-08-28 8:44 ` Alexander Graf
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