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Date:   Wed, 8 Nov 2017 22:13:16 -0800
From:   Ricardo Neri <>
To:     Linus Torvalds <>
Cc:     Denys Vlasenko <>,
        Paolo Bonzini <>,
        Peter Anvin <>, Borislav Petkov <>,
        Vlastimil Babka <>,
        Tony Luck <>,
        Fenghua Yu <>,
        Josh Poimboeuf <>,
        Borislav Petkov <>,
        Brian Gerst <>,
        Jonathan Corbet <>,
        "Ravi V. Shankar" <>,
        Chris Metcalf <>,
        Andrew Morton <>,
        Paul Gortmaker <>,
        Masami Hiramatsu <>,
        Andrew Lutomirski <>,
        Dave Hansen <>,,
        "Michael S. Tsirkin" <>,
        Linux Kernel Mailing List <>,
        Peter Zijlstra <>,
        Chen Yucong <>, Ingo Molnar <>,
        Jiri Slaby <>, Shuah Khan <>,
        Thomas Gleixner <>,
Subject: Re: [tip:x86/asm] x86/umip: Add emulation code for UMIP instructions

On Wed, Nov 08, 2017 at 08:34:45AM -0800, Linus Torvalds wrote:
> On Wed, Nov 8, 2017 at 8:14 AM, Denys Vlasenko <> wrote:
> >
> > Can we avoid maintain emulation of these isns, by asking Wine to remove
> > their use instead?
> If we ask the Wine people to remove the instruction use, that may mean
> that we can avoid the emulation in four or five _years_ once everybody
> has updated.
> But it wouldn't mean that we could avoid it today.
> We *do* probably want to print a warning about these instructions,
> whether emulated or not. If emulated, we want to print a warning about
> the emulation being expensive (as a nudge to the Wine people to not do
> that), and if _not_ emulated, we'd want to print a warning about why
> people suddenly got a SIGSEGV in case there are programs that use
> those instructions that people didn't even think of.

I am preparing a set of complementary patches now that the series made it
to the tip tree. I can include these updates as well.
> But make it ratelimit the warning (perhaps at most once every few
> minutes or whatever), so that people won't flood message logs just
> because they have old stupid programs that use those things.

Will do.

Thanks and BR,

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