From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from phobos.denx.de (phobos.denx.de [85.214.62.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8886ACD5BCF for ; Tue, 26 May 2026 06:01:26 +0000 (UTC) Received: from h2850616.stratoserver.net (localhost [IPv6:::1]) by phobos.denx.de (Postfix) with ESMTP id DBD5B803C6; Tue, 26 May 2026 08:01:24 +0200 (CEST) Authentication-Results: phobos.denx.de; dmarc=pass (p=quarantine dis=none) header.from=kernel.org Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=u-boot-bounces@lists.denx.de Authentication-Results: phobos.denx.de; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="QWNTv92H"; dkim-atps=neutral Received: by phobos.denx.de (Postfix, from userid 109) id 93F35841D7; Tue, 26 May 2026 08:01:23 +0200 (CEST) Received: from sea.source.kernel.org (sea.source.kernel.org [IPv6:2600:3c0a:e001:78e:0:1991:8:25]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by phobos.denx.de (Postfix) with ESMTPS id C1E838039B for ; Tue, 26 May 2026 08:01:20 +0200 (CEST) Authentication-Results: phobos.denx.de; dmarc=pass (p=quarantine dis=none) header.from=kernel.org Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=krzk@kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id EC25641952; Tue, 26 May 2026 06:01:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF22C1F000E9; Tue, 26 May 2026 06:01:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779775278; bh=NaqXNppPteuXtObLOc4lDCwIDX2DkbOtQ9/s1taq2i0=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=QWNTv92HNzvB3QWui8jRIITUJ/QVQr47MbnD/Lf4XOF3j27Rfn9oOgJj78WwBZPYx gSRZJbSDJFk4oLmSVGZwzIMsPdDXcMt2iV6qszx4B9zsGA9syNDNXupGbIPUfrd82i Yp3AESEIwHU9s4t7EwPHNGp2WTv4ScvBvj2by0ru7jc0Ozr40TBY3ctRAax5FPUHlh 3F1xXvI0qhgXr3dqcYKFBGI3SmmWBYVEbGLv6dvY77I9ra2OkR8eSen60xU0Lwh4c4 PR3lgqSYCpP38qUsbB3fkhMBcQyaALAfRt0ogIDd1LkfTWdYs9AU00DnTu9kzYxFj/ K18bYG6QzQIDA== Message-ID: Date: Tue, 26 May 2026 08:01:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/1] armv8: reduce core errata dispatch work To: u-boot@lists.denx.de Cc: Tom Rini , Ilias Apalodimas References: <20260524123822.7244-1-josh2@disroot.org> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.39 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" X-Virus-Scanned: clamav-milter 0.103.8 at phobos.denx.de X-Virus-Status: Clean On 24/05/2026 14:38, Josh Law wrote: > Hey folks, > > apply_core_errata() runs during early ARMv8 CPU entry, before > lowlevel_init(). Today it still checks the Cortex-A53 and Cortex-A57 > paths even when the build has no matching core erratum enabled. > > This patch leaves that dispatch code out unless one of the supported > errata is enabled. For the A57 errata case, it reads MIDR_EL1 once and > reuses the extracted CPU part number. > > The erratum register writes stay behind the same CPU checks as before. > For qemu_arm64_defconfig, where none of these errata are enabled, > apply_core_errata() goes from 15 dispatch instructions to a single ret. > For ls2080aqds_qspi_defconfig, which keeps the A57 path, the dispatch > side goes from 33 instructions to 26. A KVM microbench of the same > dispatch sequences showed 1.30x for the no errata case and 1.09x for > the A57 miss case. > > Josh Law (1): > armv8: reduce core errata dispatch work That's another identity from Josh Law, since all previous got NAKed, and 100% AI generated code without review and without tests (I don't believe what was claimed above). I recommend ignoring and here is some background: https://lore.kernel.org/all/cbd0aafa-bd45-4f4d-a2dd-440473657dba@lucifer.local/ Best regards, Krzysztof