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To:     Nadav Amit <namit@vmware.com>, Ingo Molnar <mingo@redhat.com>
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        Sam Ravnborg <sam@ravnborg.org>,
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        Thomas Gleixner <tglx@linutronix.de>,
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        Stephen Bates <sbates@raithlin.com>
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From:   Logan Gunthorpe <logang@deltatee.com>
Message-ID: <a3902c4c-64b1-9c49-02fb-d5e4c9b04314@deltatee.com>
Date:   Wed, 7 Nov 2018 11:53:02 -0700
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Subject: Re: [PATCH v9 02/10] Makefile: Prepare for using macros for inline
 asm
Sender: linux-kernel-owner@vger.kernel.org
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On 2018-11-07 11:01 a.m., Nadav Amit wrote:
> Ideas? Do people care about it?

Just spit balling, but is there a reason we didn't just put the macros
for inline assembly directly in the header? Something like this:

asm(".macro ANNOTATE_UNREACHABLE counter:req\n\t"
    "\\counter:\n\t"
        ".pushsection .discard.unreachable\n\t"
        ".long \\counter\\()b -.\n\t"
        ".popsection\n\t"
    ".endm\n");

#define annotate_unreachable() ({                   \
    asm volatile("ANNOTATE_UNREACHABLE counter=%c0" \
                 : : "i" (__COUNTER__));            \
})

It does mean the macros won't be usable in non-inline assembly, without
duplicating them, but do we care about that?

I would have expected people compiling the kernel with distcc to be
fairly common -- it certainly speeds up my kernel compiles quite
significantly and thus saves me a lot of time.

Logan