From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Gavin Shan <gshan@redhat.com>
Cc: kvm@vger.kernel.org, pbonzini@redhat.com, rkrcmar@redhat.com,
paulus@ozlabs.org, jhogan@kernel.org, drjones@redhat.com,
Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH 3/3] kvm/arm: Standardize kvm exit reason field
Date: Mon, 16 Dec 2019 10:14:16 +0100 [thread overview]
Message-ID: <87r214aazb.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <b7b6b18c-1d51-b0c2-32df-95e0b7a7c1e5@redhat.com>
Gavin Shan <gshan@redhat.com> writes:
> On 12/13/19 8:47 PM, Marc Zyngier wrote:
>> On 2019-12-13 00:50, Gavin Shan wrote:
>>>
>>> Yeah, I think it is ABI change unfortunately, but I'm not sure how
>>> many applications are using this filter.
>>
>> Nobody can tell. The problem is that someone will write a script that
>> parses this trace point based on an older kernel release (such as
>> what the distros are shipping today), and two years from now will
>> shout at you (and me) for having broken their toy.
>>
>
> Well, I would like to receive Vitaly's comments here. Vitaly, it seems it's
> more realistic to fix the issue from kvm_stat side according to the comments
> given by Marc?
>
Sure, if we decide to treat tracepoints as ABI then fixing users is
likely the way to go. Personally, I think that we should have certain
freedom with them and consider only tools which live in linux.git when
making changes (and changing the tool to match in the same patch series
is OK from this PoV, no need to support all possible versions of the
tool).
Also, we can be a bit more conservative and in this particular case
instead of renaming fields just add 'exit_reason' to all architectures
where it's missing. For ARM, 'esr_ec' will then stay with what it is and
'exit_reason' may contain something different (like the information why
the guest exited actually). But I don't know much about ARM specifics
and I'm not sure how feasible the suggestion would be.
--
Vitaly
next prev parent reply other threads:[~2019-12-16 9:14 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-12 2:45 [PATCH 3/3] kvm/arm: Standardize kvm exit reason field Gavin Shan
2019-12-12 9:23 ` Marc Zyngier
2019-12-13 0:50 ` Gavin Shan
2019-12-13 9:47 ` Marc Zyngier
2019-12-13 23:14 ` Gavin Shan
2019-12-16 9:14 ` Vitaly Kuznetsov [this message]
2019-12-16 9:35 ` Marc Zyngier
2019-12-17 2:03 ` Gavin Shan
2019-12-17 10:56 ` Paolo Bonzini
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