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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68F01C433C1 for ; Sun, 28 Mar 2021 21:59:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2E6F661585 for ; Sun, 28 Mar 2021 21:59:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231461AbhC1V6d (ORCPT ); Sun, 28 Mar 2021 17:58:33 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:51004 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229656AbhC1V6N (ORCPT ); Sun, 28 Mar 2021 17:58:13 -0400 Received: (from willy@localhost) by pcw.home.local (8.15.2/8.15.2/Submit) id 12SLw7ZK026449; Sun, 28 Mar 2021 23:58:07 +0200 Date: Sun, 28 Mar 2021 23:58:07 +0200 From: Willy Tarreau To: Andy Shevchenko Cc: Thomas Gleixner , Mateusz Jonczyk , "linux-kernel@vger.kernel.org" Subject: Re: Testers wanted: Atom netbooks with x86_64 disabled by BIOS Message-ID: <20210328215807.GA26428@1wt.eu> References: <20210327203218.119372-1-mat.jonczyk@o2.pl> <20210327211322.121708-1-mat.jonczyk@o2.pl> <20210327232551.GA20783@1wt.eu> <87lfa8cchf.ffs@nanos.tec.linutronix.de> <20210328061837.GA22710@1wt.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Mar 28, 2021 at 11:14:05PM +0300, Andy Shevchenko wrote: > On Sunday, March 28, 2021, Willy Tarreau wrote: > > > Hi Thomas, > > > > On Sun, Mar 28, 2021 at 03:07:24AM +0200, Thomas Gleixner wrote: > > > On Sun, Mar 28 2021 at 00:25, Willy Tarreau wrote: > > > > On Sat, Mar 27, 2021 at 10:13:22PM +0100, Mateusz Jonczyk wrote: > > > > FWIW I tested on my ASUS 1025C which runs on an Atom N2600 forced to > > > > 32-bit. I had already tried in the past but wanted to give it a try > > > > again in case I'd have missed anything. Sadly it didn't work, I'm > > > > still getting the "requires an x86-64 CPU" message. > > > > > > > > Given these machines were really cheap, I've always suspected that they > > > > employ cheaper, low-grade CPUs, possibly having been subject to reduced > > > > tests where x86_64-specific parts were not even verified and might be > > > > defective. This may explain why they forcefully disable long mode > > there, > > > > but that's just speculation. > > > > > > There are some of these '32bit only' CPUs out there in the wild which > > > actually support long mode. Some of them even do not have the long mode > > > CPUID bit fused out. > > > > Yes, I'm aware of this as well. We might even have talked to the same > > "victim" :-) > > > > > But whether it works is a different story: > > > > > > - If the CPUID bit is on, then the chance is high, but it runs out of > > > spec (guarantee wise) > > > > > > - If it's off is still might work by some definition of work as they > > > might have fused off more or there are actual defects in some 64bit > > > only area which are irrelevant when in 32bit mode. > > > > > > Even if it could work perfectly fine, the BIOS/SMM/ucode can prevent > > > switching to long mode. > > > > > > It's a lost cause. > > > > I agree. While I bought this netbook to have a 64-bit CPU and was extremely > > disappointed, > > > Where did you get an idea that it had 64-bit SoC from? It's an N2600, and I bought this laptop because N2600 supports 64-bit (and do have another mini-itx motherboard at work with the same CPU on it working pretty well in 64-bit): https://ark.intel.com/content/www/us/en/ark/products/58916/intel-atom-processor-n2600-1m-cache-1-6-ghz.html > Atom Based 64-bit ones are Bay Trail, Cherry Trail, Tangier (Merrifield), > Anniedale (Moorefield) and all based on Skylake family (Apollo Lake, > Broxton, Gemini Lake, ...). Well, to be honest, I've never been able to remind (nor sort) all these totally crazy names. The day someone gives me a mnemotechnic hint to remind them and their ordering, that will make me reconsider them. For now they're all "something lake", and I find it particularly difficult to map them to SKUs. Cheers, Willy