From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EE7493C0C for ; Wed, 7 Jan 2026 03:57:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767758275; cv=none; b=Nd+1kGsZIJ5xGfciDh7t7W12BEdes1L+/OUS63f+I9pufI4U09JU6A4bo4Tn3oRk+yNy6+BHR3SRzKMIBtamTHLEnD23HcsxW1nvEJymT+oLfO2D3HcYss5W52syF09TSMZ0Qmt3VxR44vzboZUNdMvtskTgqCg/SDYLqdpaYss= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767758275; c=relaxed/simple; bh=Je98NeZ64TWtnaovnVyoWoswxPs/9tZ3P0laUQcKycQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eS59sNEn/CqA8LvaWXjNstbrD5by7gRa8l4Z+Fggq/XuRUBO6SwQ6ZhO3chwuttYZhwnuecHIHC0ecseAjW1y7/R2ry9JUEKxjfQjUd6dd/XpZSoZbP2Nf0/fScV/RZaFdc0ksBIdZWHBssrUyrgE6qI9R6X4mc7EVl0hZjvg9s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=dtBf0uId; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="dtBf0uId" Received: from [IPV6:2601:646:8081:9483:178c:dccb:2d71:85fe] ([IPv6:2601:646:8081:9483:178c:dccb:2d71:85fe]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 6073vMwB658358 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Tue, 6 Jan 2026 19:57:22 -0800 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 6073vMwB658358 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2025122301; t=1767758243; bh=1jQ6fdkCwZxVseyBoqw5NBARKOCbLX2eXz76XoXv4hE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=dtBf0uIdh4oGVA8/ovB96LbnjaIaKVysyDFaojONXNbWRyyjkWx8IM5DNQCjKDuE5 haycZdo8Hw1Sua1lrR11HEzNSR+hWzM9nllIiQom8C4/XxDRLkEnnMbBFT13DXQ08q lfoMflczOCttyd3InBBqivIfvPjcsmJDhmqCw+llD9aeF9YgImBzB2Uc+fNmKqcymx IMCEcV92UHNtBcPDaWrCtsIjR9l2l+AQj/lZeyf85WowYOJIVnLV9or+aQegWQHHxL yO020MSNY09OdPBfRkG3UVYxSnMi9+Esv41UdCRw6PpWhNFn9DSAo2aN91DOWUGV6H ZD+QKkwYdEn0Q== Message-ID: <8cb799cb-a3ff-4257-b03d-661b893a2663@zytor.com> Date: Tue, 6 Jan 2026 19:57:22 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH -v3 0/15] x86: Remove support for TSC-less and CX8-less CPUs To: Borislav Petkov , "Ahmed S. Darwish" Cc: Brian Gerst , Ingo Molnar , linux-kernel@vger.kernel.org, Andrew Cooper , Ard Biesheuvel , Arnd Bergmann , Dave Hansen , John Ogness , Linus Torvalds , Peter Zijlstra , Thomas Gleixner References: <20251214084710.3606385-1-mingo@kernel.org> <20260104130803.GDaVpmM7vNwP-k0Z0a@fat_crate.local> Content-Language: en-US, sv-SE From: "H. Peter Anvin" In-Reply-To: <20260104130803.GDaVpmM7vNwP-k0Z0a@fat_crate.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2026-01-04 05:08, Borislav Petkov wrote: > On Mon, Dec 15, 2025 at 02:55:27PM +0100, Ahmed S. Darwish wrote: >> If it does, then we can also remove X86_FEATURE_CPUID from word 3: >> >> --- linux.orig/arch/x86/include/asm/cpufeatures.h >> +++ linux/arch/x86/include/asm/cpufeatures.h >> @@ -94,3 +94,3 @@ >> #define X86_FEATURE_NONSTOP_TSC ( 3*32+24) /* "nonstop_tsc" TSC does not stop in C states */ >> -#define X86_FEATURE_CPUID ( 3*32+25) /* "cpuid" CPU has CPUID instruction itself */ >> +/* Reserved ( 3*32+25) */ > > s/Reserved/Free/ > > so that it gets reused. > Please DON'T do this. I have been cleaning up the boot code and it turns out that having this flag available makes the error message generating code in the boot stub a lot nicer. -hpa