From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.31 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794402251; b=Hm6jlH2qVGfvqfRdZKLqlM6PSqawD5NOfTgQ/D0frNj4ig4W+i6EYvTgqyQ6VJU5/vKA ADzrX4UmsQFgwoh44jfGLP8tR5NHHcFVSBcL2Hx3wu2aoStjj3EAgT7wA004+avgNdVRT wp8W5j/jZ3W38Pu3I5uBxyeQd7zpwqbbQHYDPhsjPheuwArFOvvfDvFNmAkdn6j7hryG9 eLKMaQ+5SfXU8WnljbTESVdC26u7evmly9mTGcFRrIN9LsC6+j6UhPsjTPLiSrw4IMqrg WKk9Lx0xi7PuG534D/CU/baiCT8tKliTBt12Z8/HNDaTE84AXXP0QkEbumHgWD5nmxA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794402251; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-ID: X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=+ibl+xs66yD86wh5INakXzfw8v0V7RfphGaR6jB5XrI=; b=kkNE1gjamYcogjW6232Tairc+kiDh5Jsar6j0rKm+PGS8M/CS4WfnNrMpws7wyrJ0WFy GW88+Ult1ui0KlxQoCPTFd1XZD8dEDbXADfwO7invToIhFkzXWkjZmsfeo0rfJ4nhUIZl c/eu5XKrynKuV5abHEtnUorVchWLZiOgNAWhZkW7rKTghXmaLZm1sBVnb6f+8/9qZ78h9 5e9vO3nFiTJx17yTi1DHsb4e6giXEENCYR2SZBlGhxp5u/LjJRW2ELJFEfybWL3GahVI4 g5mtGef8MvX9r3WObP1Idbn4Km8wHY71PRVEpoBWHr9LYr5l+3iz49+MLs8C9NlY2Lg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=ULpQmAld; arc=none smtp.remote-ip=95.215.58.31 Received: from mta1.migadu.com (unknown [95.215.58.31]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 35F46606A32E for ; Wed, 11 Nov 2026 13:04:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 35F46606A32E Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=ULpQmAld X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=PNo9eQqUCQ0H6xEIxoWm0pGinAn55h2xXAqO/yeQE58=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794402248; v=1; x=1795007048; b=ULpQmAldDNEGQPEemmARZ/j2g2idpw6brjJcB7CsGqeZtC3PDHwc2vFJXumhZ7p2nwa0S7GY 9jE3EdmcW3i/FKCI0CQ8LrPfERXOOUKGEHGFkV7WX7KWZa8bMKswXehGY++PXgCcDuJ9Y5500Pn KVnbc+de6aVQIV2EHRA5wXQ4= X-Envelope-To: linux-kernel@vger.kernel.org Received: by mta12.migadu.com with ESMTPS id 42f504bcf6d2e3ca; Wed, 11 Nov 2026 13:04:07 +0000 X-Mizu-Trace-ID: 42f504bcf6d2e3ca X-Migadu-Flow: FLOW_OUT From: Usama Arif To: Linus Torvalds Cc: Usama Arif , david.laight.linux@gmail.com, bp@alien8.de, dave.hansen@linux.intel.com, dsterba@suse.com, hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@redhat.com, terrelln@fb.com, tglx@kernel.org, x86@kernel.org, kas@kernel.org, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, kernel-team@meta.com Subject: Re: [PATCH v2] x86/lib: Use REP MOVSB for large memcpy() on ERMS CPUs without FSRM Date: Wed, 11 Nov 2026 05:04:03 -0800 Message-ID: <20261111130404.2662582-1-usama.arif@linux.dev> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Tue, 10 Nov 2026 09:53:07 -0800 Linus Torvalds wrote: > On Wed, 4 Nov 2026 at 14:28, Usama Arif wrote: > > > > + ALTERNATIVE __stringify(cmpq $0x20, %rcx; jb .Lhandle_tail), \ > > + __stringify(rep movsb; RET), X86_FEATURE_FSRM > > Let's not do that. > > Putting magic things like RET in alternatives is just a bad bad idea. I will send v3 today with RET in ordinary text. Thanks! Usama > > Linus >