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Date:      Mon, 26 Sep 2016 10:51:29 +0300
From:      Konstantin Belousov <kostikbel@gmail.com>
To:        Colin Percival <cperciva@tarsnap.com>
Cc:        Bruce Evans <brde@optusnet.com.au>, src-committers@FreeBSD.org, svn-src-all@FreeBSD.org, svn-src-head@FreeBSD.org
Subject:   Re: svn commit: r306319 - head/sys/i386/i386
Message-ID:  <20160926075129.GD38409@kib.kiev.ua>
In-Reply-To: <0100015765538d1e-07598541-d22e-4eac-8382-b9bad08db716-000000@email.amazonses.com>
References:  <201609251839.u8PIdO7t050380@repo.freebsd.org> <0100015762ed107c-206ced2e-2389-462f-afe0-cec7d6c34fb8-000000@email.amazonses.com> <20160926164406.T806@besplex.bde.org> <0100015765538d1e-07598541-d22e-4eac-8382-b9bad08db716-000000@email.amazonses.com>

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On Mon, Sep 26, 2016 at 07:09:17AM +0000, Colin Percival wrote:
> Traditionally x86 CPUs would generate an invalid-opcode fault if redundant
> instruction prefixes resulted in an instruction exceeding 15 bytes.  This
> behaviour might have changed in the past two decades, but I doubt it.

It did not, 15 bytes is the current limit.  In fact, the longest AVX
VEX-encoded instructions are 11 bytes without prefixes, AFAIR.



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