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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 E0F1DC433DB for ; Sat, 27 Mar 2021 21:14:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9C3846196C for ; Sat, 27 Mar 2021 21:14:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230224AbhC0VNs (ORCPT ); Sat, 27 Mar 2021 17:13:48 -0400 Received: from mx-out.tlen.pl ([193.222.135.158]:21542 "EHLO mx-out.tlen.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230015AbhC0VNf (ORCPT ); Sat, 27 Mar 2021 17:13:35 -0400 Received: (wp-smtpd smtp.tlen.pl 40850 invoked from network); 27 Mar 2021 22:13:32 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=o2.pl; s=1024a; t=1616879612; bh=6XmFuodXSwp/ahPWGzc07JUgMKXhdAiUWCGT3utXIz8=; h=From:To:Cc:Subject; b=VcwuxU4kkulEtKXK9k3zTge4AI8VbDODz8TlZ0g7+2ovjTU3RJ0kax9w7LR2dcbu3 Sl+ismmdQSWH+PmN8H2O8Jl6BPgMq0S+6x5eQseOO2GBL0CDFxT8/+f3U0czl8z2gI 8w81T/DS0AramsgYkEfYYB9mx3oRebDQxklJ4jgA= Received: from aclp172.neoplus.adsl.tpnet.pl (HELO localhost.localdomain) (mat.jonczyk@o2.pl@[83.10.117.172]) (envelope-sender ) by smtp.tlen.pl (WP-SMTPD) with SMTP for ; 27 Mar 2021 22:13:32 +0100 From: =?UTF-8?q?Mateusz=20Jo=C5=84czyk?= To: linux-kernel@vger.kernel.org Cc: =?UTF-8?q?Mateusz=20Jo=C5=84czyk?= Subject: Re: Testers wanted: Atom netbooks with x86_64 disabled by BIOS Date: Sat, 27 Mar 2021 22:13:22 +0100 Message-Id: <20210327211322.121708-1-mat.jonczyk@o2.pl> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210327203218.119372-1-mat.jonczyk@o2.pl> References: <20210327203218.119372-1-mat.jonczyk@o2.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-WP-DKIM-Status: good (id: o2.pl) X-WP-MailID: 4154caa4a390fb312713de6c19cca6ab X-WP-AV: skaner antywirusowy Poczty o2 X-WP-SPAM: NO 0000000 [kbOE] Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org W dniu 27.03.2021 o 21:32, Mateusz Jończyk pisze: > Hello, > > There are some netbooks with Intel Atom processors that have 64-bit > support disabled by BIOS. Theoretically, the processor supports 64-bit > operation, but BIOS allows only 32-bit code to run. > > I wonder whether the 64-bit mode is really disabled in the CPU or only > hidden in the CPUID flags. If the latter, the computer could be made to > run a 64-bit kernel. > > Similarly, there are some Pentium M processors that support PAE > (Physical Address Extensions), but do not show this in CPUID. They could > be made to run distributions that require PAE with the "forcepae" kernel > command line parameter. > > I would like to ask people with such netbooks to try to run a 64-bit kernel > with this patch applied. > > When a patched 64-bit kernel is run in `qemu-system-i386`, the virtual > machine restarts instantly. Without this patch in such a case a 64-bit > kernel hangs indefinitely (inside .Lno_longmode in head_64.S). I have made two mistakes: - I left commented out code, - I have commented out lines with '#'. The code compiled though. Attaching corrected patch, please excuse me. Greetings, Mateusz Signed-off-by: Mateusz Jończyk --- arch/x86/boot/compressed/head_64.S | 2 -- 1 file changed, 2 deletions(-) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index e94874f4bbc1..a9f0415da7c2 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -111,8 +111,6 @@ SYM_FUNC_START(startup_32) leal rva(boot_stack_end)(%ebp), %esp call verify_cpu - testl %eax, %eax - jnz .Lno_longmode /* * Compute the delta between where we were compiled to run at -- 2.25.1