From: "Alex Bennée" <alex.bennee@linaro.org>
To: "Daniel P. Berrangé" <berrange@redhat.com>
Cc: "reviewer:Incompatible changes" <libvir-list@redhat.com>,
qemu-devel@nongnu.org, robhenry@microsoft.com,
aaron@os.amperecomputing.com, vilanova@imperial.ac.uk,
mahmoudabdalghany@outlook.com, minyihh@uci.edu, cota@braap.org,
stefanha@redhat.com, mohamad.gebai@gmail.com,
kuhn.chenqun@huawei.com, matheus.ferst@eldorado.org.br
Subject: Re: [PATCH v1 5/7] docs: mark intention to deprecate TCG tracing functionality
Date: Mon, 17 May 2021 11:47:11 +0100 [thread overview]
Message-ID: <87eee5eiua.fsf@linaro.org> (raw)
In-Reply-To: <YJJ41bUEY+Gfkw/Z@redhat.com>
Daniel P. Berrangé <berrange@redhat.com> writes:
> On Wed, May 05, 2021 at 11:41:46AM +0100, Alex Bennée wrote:
>>
>> Alex Bennée <alex.bennee@linaro.org> writes:
>>
>> > Daniel P. Berrangé <berrange@redhat.com> writes:
>> >
>> >> On Wed, May 05, 2021 at 10:22:57AM +0100, Alex Bennée wrote:
>> <snip>
>> >>> +TCG introspection features
>> >>> +--------------------------
>> >>> +
>> >>> +TCG trace-events (since 6.1)
>> >>> +''''''''''''''''''''''''''''
>> >>> +
>> >>> +The ability to add new TCG trace points has bit rotted and as the
>> >>
>> >> When you say this "has bit rotted", just how bad is the situation ?
>> >>
>> >> Is the TCG tracing still usable at all, or is is fully broken
>> >> already ?
>> >
>> > Well patches 6/7 got it working for generic TCG things. I haven't been
>> > able to get the architecture one working but I suspect that is some sort
>> > of interaction between the per-arch trace header generation that I
>> > haven't quite figured out yet.
>>
>> Ahh it's since 7609ffb919 (trace: fix tcg tracing build breakage) which
>> limited tcg/vcpu events to the root trace-events file.
>
> That commit is from release 2.10.0.
>
> The other commit mentioned in patch 6 (73ff061032) is from 2.12.0.
>
> So no one has been able to use this feature for 3+ years already.
>
> Is it actually worth fixing and then deprecating for 2 releases before
> deleting, as opposed to just deleting the broken code today on basis
> that it can't have any current users ?
Well I can get it up and running with the aforementioned patches and it
seems reasonable to give some notice. I'm happy to defer to Stefan here
though as it's his sub-system.
>
> Regards,
> Daniel
--
Alex Bennée
next prev parent reply other threads:[~2021-05-17 10:49 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-05 9:22 [PATCH v1 0/7] plugins/next (windows, leaks, tcg tracing) Alex Bennée
2021-05-05 9:22 ` [PATCH v1 1/7] plugins: Update qemu-plugins.symbols to match qemu-plugins.h Alex Bennée
2021-05-05 9:22 ` [PATCH v1 2/7] plugins: Move all typedef and type declaration to the front of the qemu-plugin.h Alex Bennée
2021-05-05 9:22 ` [PATCH v1 3/7] plugins/hotblocks: Properly freed the hash table values Alex Bennée
2021-05-05 9:22 ` [PATCH v1 4/7] plugins/hotpages: " Alex Bennée
2021-05-05 9:22 ` [PATCH v1 5/7] docs: mark intention to deprecate TCG tracing functionality Alex Bennée
2021-05-05 9:33 ` Daniel P. Berrangé
2021-05-05 10:35 ` Alex Bennée
2021-05-05 10:41 ` Alex Bennée
2021-05-05 10:52 ` Daniel P. Berrangé
2021-05-17 10:47 ` Alex Bennée [this message]
2021-05-17 13:44 ` Stefan Hajnoczi
2021-05-05 9:22 ` [PATCH v1 6/7] scripts/tracetool: don't barf validating TCG types Alex Bennée
2021-05-05 9:22 ` [PATCH v1 7/7] tcg: add trace events for [exit|goto]_tb and goto_ptr Alex Bennée
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