From: Paolo Bonzini <pbonzini@redhat.com>
To: Ben Gardon <bgardon@google.com>,
Sean Christopherson <seanjc@google.com>,
Jim Mattson <jmattson@google.com>,
Junaid Shahid <junaids@google.com>, Peter Xu <peterx@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>
Subject: Re: Writable module parameters in KVM
Date: Wed, 26 May 2021 12:49:11 +0200 [thread overview]
Message-ID: <35fe7a86-d808-00e9-a6aa-e77b731bd4bf@redhat.com> (raw)
In-Reply-To: <CANgfPd_Pq2MkRUZiJynh7zkNuKE5oFGRjKeCjmgYP4vwvfMc1g@mail.gmail.com>
On 26/05/21 01:45, Ben Gardon wrote:
>
> At Google we have an informal practice of adding sysctls to control some
> KVM features. Usually these just act as simple "chicken bits" which
> allow us to turn off a feature without having to stall a kernel rollout
> if some feature causes problems. (Sysctls were used for reasons specific
> to Google infrastructure, not because they're necessarily better.)
>
> We'd like to get rid of this divergence with upstream by converting the
> sysctls to writable module parameters, but I'm not sure what the general
> guidance is on writable module parameters. Looking through KVM, it seems
> like we have several writable parameters, but they're mostly read-only.
Sure, making them writable is okay. Most KVM parameters are read-only
because it's much simpler (the usecase for introducing them was simply
"test what would happen on old processors"). What are these features
that you'd like to control?
> I also don't see central documentation of the module parameters. They're
> mentioned in the documentation for other features, but don't have their
> own section / file. Should they?
They probably should, yes.
Paolo
next parent reply other threads:[~2021-05-26 10:49 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CANgfPd_Pq2MkRUZiJynh7zkNuKE5oFGRjKeCjmgYP4vwvfMc1g@mail.gmail.com>
2021-05-26 10:49 ` Paolo Bonzini [this message]
2021-05-26 11:10 ` Writable module parameters in KVM Maxim Levitsky
2021-05-26 15:44 ` Sean Christopherson
2021-05-26 16:30 ` Paolo Bonzini
2021-05-26 20:09 ` Ben Gardon
2021-05-26 21:16 ` Sean Christopherson
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