linux-kernel - Re: [PATCH] KVM: deprecate KVM_WERROR in favor of general WERROR

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Message-ID: <20231009144944.17c8eba3@kernel.org>
Date:   Mon, 9 Oct 2023 14:49:44 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Sean Christopherson <seanjc@...gle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     pbonzini@...hat.com, workflows@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH] KVM: deprecate KVM_WERROR in favor of general WERROR

On Mon, 9 Oct 2023 12:33:53 -0700 Sean Christopherson wrote:
> > We do have sympathy for these folks, we are mostly volunteers after
> > all. At the same time someone's under-investment should not be causing
> > pain to those of us who _do_ build test stuff carefully.  
> 
> This is a bit over the top.  Yeah, I need to add W=1 to my build scripts, but that's
> not a lack of investment, just an oversight.  Though in this case it likely wouldn't
> have made any difference since Paolo grabbed the patches directly and might have
> even bypassed linux-next.  But again I would argue that's bad process, not a lack
> of investment.

If you do invest in build testing automation, why can't your automation
count warnings rather than depend on WERROR? I don't understand.

> > Rather than tweak stuff I'd prefer if we could agree that local -Werror
> > is anti-social :(
> > 
> > The global WERROR seems to be a good compromise.  
> 
> I disagree.  WERROR simply doesn't provide the same coverage.  E.g. it can't be
> enabled for i386 without tuning FRAME_WARN, which (a) won't be at all obvious to
> the average contributor and (b) increasing FRAME_WARN effectively reduces the
> test coverage of KVM i386.
> 
> For KVM x86, I want the rules for contributing to be clearly documented, and as
> simple as possible.  I don't see a sane way to achieve that with WERROR=y.

Linus, you created the global WERROR option. Do you have an opinion
on whether random subsystems should create their own WERROR flags?
W=1 warning got in thru KVM and since they have a KVM_WERROR which
defaults to enabled it broke build testing in networking.
Randomly sprinkled -Werrors are fragile. Can we ask people to stop
using them now that the global ERROR exists?