From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <luke.leighton@gmail.com>
Received: from mail-ua1-x92d.google.com (mail-ua1-x92d.google.com
 [IPv6:2607:f8b0:4864:20::92d])
 by sourceware.org (Postfix) with ESMTPS id 3F61F3851C24
 for <binutils@sourceware.org>; Tue, 31 May 2022 04:06:18 +0000 (GMT)
DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 3F61F3851C24
Received: by mail-ua1-x92d.google.com with SMTP id m10so702403uao.11
 for <binutils@sourceware.org>; Mon, 30 May 2022 21:06:18 -0700 (PDT)
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
 d=1e100.net; s=20210112;
 h=x-gm-message-state:mime-version:references:in-reply-to:from:date
 :message-id:subject:to:cc;
 bh=MYnI9VOB4JzJnoW6JsaYQ2SgodT6Yg5t3r4JWxHfsEA=;
 b=7MCP9R1VMQpChMFps+5NvN5UwLnEgGlb3MKa+CiXzxupV/vedUcpa9kImhVQf7iCLu
 HvzWV+l0ofipC2eegy/bdqXBZ15cXNq2spaTF/+A76HFn78vxfXMky9LwKefwob7RTTq
 2h+kB1nU3/bV6TtM2r786AhYstMS5agoS9lU5D1BB88reuHP8dR7UAXLoazA1wHoGavw
 z+ZjsNClQ6FW9ajjpuqhySZFOtKUO4+Ot4YFt3pPVjhrfWdGQwlSjFNO9EMWZkc0m9dG
 TTfV123wIqEEr1AgIIglBDIwS1cEMWX/mJywWc2WVAD7rI+2w7lT1+C8x2HSWI9VMX/F
 jH9g==
X-Gm-Message-State: AOAM533imvEqWPaHB0ATL0N7L4s8v+auB4OR+WzTT4AErcAhhakqfa1D
 J0s7wmCK9yf+3Z8+RogfO/7DKRaGLqRsZiLy1m4=
X-Google-Smtp-Source: ABdhPJzIyM6awsGF0nZkVkkWCEvNm798XeUlYeijycb71jzkITRtbkfsY7Env1psEb8cbmlBaNtCTXdP0CVXFGJgocA=
X-Received: by 2002:ab0:48c8:0:b0:369:3373:c05f with SMTP id
 y8-20020ab048c8000000b003693373c05fmr7748494uac.83.1653969977599; Mon, 30 May
 2022 21:06:17 -0700 (PDT)
MIME-Version: 1.0
References: <CAMqzjev3_z+uGbh-0_rdJ06+m5Fn0naeEn5jTpz9Va01JBYSKw@mail.gmail.com>
 <CAPweEDzRUQukJgnFKutun+xJpiPjvTeRSi9_irx=QrebFHg7sQ@mail.gmail.com>
 <YouFGavJxwKgUw6H@squeak.grove.modra.org>
 <CAMqzjeuUagZ3e0_uPWzopJBveUX9E6gDwu9KAOxbX_nrpibBhQ@mail.gmail.com>
 <17f6beb2-db1a-0bec-b022-168373c3921b@linux.ibm.com>
 <CAPweEDyv4T8S7m+1KjJcX8nE9EkyL_HhLAYjLoDyTDkpHXAeqQ@mail.gmail.com>
 <YpVZfBm3igJfDw2c@cleo>
In-Reply-To: <YpVZfBm3igJfDw2c@cleo>
From: lkcl <luke.leighton@gmail.com>
Date: Tue, 31 May 2022 05:06:06 +0100
Message-ID: <CAPweEDy=hF7JSK8hySZcZH-abGY+G9N-VX8=xFvsZ_kyap=fFA@mail.gmail.com>
Subject: Re: Plugin-based opcode table
To: Paul Mackerras <paulus@ozlabs.org>
Cc: Peter Bergner <bergner@linux.ibm.com>,
 Dmitry Selyutin <ghostmansd@gmail.com>, 
 Alan Modra <amodra@gmail.com>, binutils@sourceware.org, 
 Alain Williams <addw@phcomp.co.uk>
Content-Type: text/plain; charset="UTF-8"
X-Spam-Status: No, score=-0.2 required=5.0 tests=BAYES_00, DKIM_SIGNED,
 DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,
 SPF_HELO_NONE, SPF_PASS, TXREP,
 T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
 server2.sourceware.org
X-BeenThere: binutils@sourceware.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Binutils mailing list <binutils.sourceware.org>
List-Unsubscribe: <https://sourceware.org/mailman/options/binutils>,
 <mailto:binutils-request@sourceware.org?subject=unsubscribe>
List-Archive: <https://sourceware.org/pipermail/binutils/>
List-Post: <mailto:binutils@sourceware.org>
List-Help: <mailto:binutils-request@sourceware.org?subject=help>
List-Subscribe: <https://sourceware.org/mailman/listinfo/binutils>,
 <mailto:binutils-request@sourceware.org?subject=subscribe>
X-List-Received-Date: Tue, 31 May 2022 04:06:19 -0000

On Tue, May 31, 2022 at 1:14 AM Paul Mackerras <paulus@ozlabs.org> wrote:
>
> Just to clarify something below...

always appreciated, Paul.

> The problem Peter was describing was at the assembly level not the
> machine code level.  The lxvd2x instruction still exists in POWER9 and
> does the same thing that it does in POWER8.

ahh right. so an older program compiled prior to the assembler mnemonic
rename will still be binary-compatible.

> That is, the difference is in what bits you get out of the assembler
> when you write "lxvx", rather than a binary compatibility difference.

subtle, and annoying/quirky, but not something that breaks older
programs, thank goodness. important to have clarified because it
would give the false impression (to any future reader of the archives)
of an instability in the Power ISA, which would be bad.

l.