From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 2/7] KVM: arm: guest debug, define API headers
Date: Wed, 26 Nov 2014 14:14:30 +0100
Message-ID: <5475D236.1070305@redhat.com>
References: <1416931805-23223-1-git-send-email-alex.bennee@linaro.org> <1416931805-23223-3-git-send-email-alex.bennee@linaro.org> <5474B6BC.2060309@redhat.com> <CAFEAcA-ikeiciAh4RXpKQQ_pY9FRePxR7nEBUEjcaaxB0ZAAtA@mail.gmail.com> <5474BAD8.7010307@redhat.com> <87vbm2ksui.fsf@linaro.org>
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Cc: Peter Maydell <peter.maydell@linaro.org>,
	kvm-devel <kvm@vger.kernel.org>,
	arm-mail-list <linux-arm-kernel@lists.infradead.org>,
	"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
	Christoffer Dall <christoffer.dall@linaro.org>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Alexander Graf <agraf@suse.de>,
	"J. Kiszka" <jan.kiszka@siemens.com>,
	David Hildenbrand <dahi@linux.vnet.ibm.com>,
	Bharat Bhushan <r65777@freescale.com>, bp@suse.de,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	open list <linux-kernel@vger.kernel.org>
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On 26/11/2014 14:13, Alex Benn=C3=A9e wrote:
>=20
> Paolo Bonzini <pbonzini@redhat.com> writes:
>=20
>> On 25/11/2014 18:13, Peter Maydell wrote:
>>> On 25 November 2014 at 17:05, Paolo Bonzini <pbonzini@redhat.com> w=
rote:
>>>>> So there is no register that says "this breakpoint has triggered"=
 or
>>>>> "this watchpoint has triggered"?
>>> Nope. You take a debug exception; the syndrome register tells
>>> you if it was a bp or a wp, and if it was a wp the fault address
>>> register tells you the address being accessed (if it was a bp
>>> you know the program counter, obviously). The debugger is expected
>>> to be able to figure it out from there, if it cares.
>>
>> That's already good enough---do the KVM_DEBUG_EXIT_* constants match=
 the
>> syndrome register, or if not why?
>=20
> No they don't. I did consider it at the time but I was wary of pullin=
g
> too much over into the uapi headers wholesale. If your happy to do th=
at
> I'll include the change in my next version.
>=20
> I could also rationalise the exit handlers as they all pretty much do
> the same thing (save for the exit/syndrome related info). Again I was
> keeping things nicely separated in case any particular exception need=
ed
> excessive special case handling.
>=20
> Would you like those changes?

Yes, please.

Paolo