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 A1B601E5B64 for ; Tue, 24 Mar 2026 04:24:44 +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=1774326286; cv=none; b=aKYPezDn59fpDZ8TrDCZgfDWrQmeSnUj9jvGYDgs4bch36LlzEJzHruCZQU2/+0kkEcl9QxT0AKR/HXeyc2X6FLSRRRssh75hq/iW8uvniFNOx6vauO0w/imCbDbUHpTw6wu8OSX/9ZrfvKUXsskzPf76D1AkOaDYmwa2u1zIvQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774326286; c=relaxed/simple; bh=6vTiqdyaNSSfFfZtq/DdO3121ZvSIJLzrWgWwW4vCaA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=sHy4dNaCKcXnf9iaNhAnA0trlsjpL7cCjJ3M/Z+RzaFgzIFkrNVAHpNYwJcwWcfEpvfaGNfXfaTUBRFERmeA3pQYXraYICf/7Fm3xNZj2n/7YyROhNmbON+yUrOSe7+BTF+FhH64RfneIWV4Ekte75L8rX3yMy4pW7dYXmhq1Aw= 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=TIji5/AB; 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="TIji5/AB" Received: from [IPV6:2601:646:8081:9481:bc37:8e28:7f8f:c5ea] ([IPv6:2601:646:8081:9481:bc37:8e28:7f8f:c5ea]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 62O3qFXD3847723 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Mon, 23 Mar 2026 20:52:15 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 62O3qFXD3847723 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2026022301; t=1774324336; bh=x/2BP9sGp/uy/xS0Q3w0pZIrg1SG9k0N53PunjCfI1E=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=TIji5/ABlo1H39AqjAQAaVouHo19FyLodbZfbUkuf09rKjDVtHZeX9eDB7KDHljD0 7KpCUltRnr0DqpU2si55PTdyLGL/DBMGI/XgoXEwp+Uc3TN2oS+QkCNj6LqymBZdGH asCeS5q5KLlCcrhOlqL/hj6YwhrVNA/81qbkk4rwLTYhrOdrAmppD+6zdpaFf9y9Ec fV+41d67/W2YDbqojqsKCz69iJGiHwR/FZVnYzpsbOrx0rMI6MyXeKJdAN75SHTRW/ u2zqMKDCqznX1ZnNypnuyYh6pLxoZeIqfoZiiTIa0IQQWbZVH0eWaTCvQi3EjvUn6F wxnGomESUWkHw== Message-ID: <763cbc92-fda0-454e-a2dd-919671db15c3@zytor.com> Date: Mon, 23 Mar 2026 20:52:10 -0700 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 0/2] x86/fred: enable FRED by default To: Xin Li , Sohil Mehta Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "Peter Zijlstra (Intel)" , Kees Cook , "Ahmed S. Darwish" , linux-kernel@vger.kernel.org References: <20260323201510.1537333-1-hpa@zytor.com> <84489fd4-aa23-4ba1-b5a1-c1baafb6718d@intel.com> <927AE575-3C10-427E-9C4B-0238CBF8301E@zytor.com> Content-Language: en-US, sv-SE From: "H. Peter Anvin" In-Reply-To: <927AE575-3C10-427E-9C4B-0238CBF8301E@zytor.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 2026-03-23 20:05, Xin Li wrote: > > >> On Mar 23, 2026, at 6:01 PM, Sohil Mehta wrote: >> >>> @@ -1746,7 +1746,7 @@ static void __init cpu_parse_early_param(void) >>> >>> /* Minimize the gap between FRED is available and available but disabled. */ >>> arglen = cmdline_find_option(boot_command_line, "fred", arg, sizeof(arg)); >>> - if (arglen != 2 || strncmp(arg, "on", 2)) >>> + if (arglen > 0 && (arglen != 2 || strncmp(arg, "on", 2))) >>> setup_clear_cpu_cap(X86_FEATURE_FRED); >> >> Nit: Would it be better to compare with "off" rather than not on? > > +1 :) > It would change the meaning of something like "fred=0" though. -hpa