linux-kernel - Re: [PATCH v4 01/17] x86/common: Align cpu_caps_cleared and cpu_caps

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Message-ID: <20190304124433.GE32477@hirez.programming.kicks-ass.net>
Date:   Mon, 4 Mar 2019 13:44:33 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        H Peter Anvin <hpa@...or.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Ravi V Shankar <ravi.v.shankar@...el.com>,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        x86 <x86@...nel.org>, kvm@...r.kernel.org
Subject: Re: [PATCH v4 01/17] x86/common: Align cpu_caps_cleared and
 cpu_caps_set to unsigned long

On Mon, Mar 04, 2019 at 11:48:18AM +0100, Paolo Bonzini wrote:
> True that.  On the other hand btsl/btrl is also one byte smaller if no 
> operand is %r8-%r15.

Because then we loose the REX prefix, right. Now _that_ might actually
be a reason to do that :-)

> In any case, /me wonders if we should have a macro like
> 
> #define DECLARE_LE_BITMAP(name,bits) \
>         u32 name[DIV_ROUND_UP(bits, 32)] __aligned(sizeof(unsigned long))

 s/u32/__le32/

To go in bitops/le.h, sure, if there's enough users.