linux-kernel - Re: [PATCH v2 16/17] x86/insn: remove pcommit

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Date:	Tue, 12 Jul 2016 16:57:57 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Dan Williams <dan.j.williams@...el.com>
Cc:	linux-nvdimm@...1.01.org,
	Xiao Guangrong <guangrong.xiao@...ux.intel.com>,
	Josh Poimboeuf <jpoimboe@...hat.com>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	x86@...nel.org, Adrian Hunter <adrian.hunter@...el.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>, hch@....de,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Ingo Molnar <mingo@...hat.com>,
	Andy Lutomirski <luto@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>, linux-fsdevel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...e.de>,
	Ross Zwisler <ross.zwisler@...ux.intel.com>
Subject: Re: [PATCH v2 16/17] x86/insn: remove pcommit

On Sat, Jul 09, 2016 at 08:25:54PM -0700, Dan Williams wrote:
> The pcommit instruction is being deprecated in favor of either ADR
> (asynchronous DRAM refresh: flush-on-power-fail) at the platform level, or
> posted-write-queue flush addresses as defined by the ACPI 6.x NFIT (NVDIMM
> Firmware Interface Table).

>  arch/x86/include/asm/cpufeatures.h                 |    1 
>  arch/x86/include/asm/special_insns.h               |   46 --------------------
>  arch/x86/lib/x86-opcode-map.txt                    |    2 -
>  tools/objtool/arch/x86/insn/x86-opcode-map.txt     |    2 -
>  tools/perf/arch/x86/tests/insn-x86-dat-32.c        |    2 -
>  tools/perf/arch/x86/tests/insn-x86-dat-64.c        |    2 -
>  tools/perf/arch/x86/tests/insn-x86-dat-src.c       |    4 --

Just deprecated, or is it completely eradicated, removed from history,
will never ever happen and we'll reissue the opcode for something else?

Because if its only deprecated then removing it from the instruction
decoders seems wrong, old binaries might still contain the opcode.