From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f72.google.com (mail-pa0-f72.google.com [209.85.220.72]) by kanga.kvack.org (Postfix) with ESMTP id ED85B828E1 for ; Wed, 6 Jul 2016 12:02:27 -0400 (EDT) Received: by mail-pa0-f72.google.com with SMTP id ts6so463752120pac.1 for ; Wed, 06 Jul 2016 09:02:27 -0700 (PDT) Received: from blackbird.sr71.net (www.sr71.net. [198.145.64.142]) by mx.google.com with ESMTP id m69si4770179pfc.279.2016.07.06.09.02.26 for ; Wed, 06 Jul 2016 09:02:26 -0700 (PDT) Subject: Re: [PATCH 3/4] x86: disallow running with 32-bit PTEs to work around erratum References: <006001d1d5a8$dd26e1f0$9774a5d0$@alibaba-inc.com> <006401d1d5ab$5e154070$1a3fc150$@alibaba-inc.com> From: Dave Hansen Message-ID: <577D2B91.2030007@sr71.net> Date: Wed, 6 Jul 2016 09:02:25 -0700 MIME-Version: 1.0 In-Reply-To: <006401d1d5ab$5e154070$1a3fc150$@alibaba-inc.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Hillf Danton , Dave Hansen Cc: linux-kernel , linux-mm@kvack.org On 07/03/2016 09:20 PM, Hillf Danton wrote: ... >> When we have 64-bit PTEs (64-bit mode or 32-bit PAE), we were able >> to move the swap PTE format around to avoid these troublesome bits. >> But, 32-bit non-PAE is tight on bits. So, disallow it from running >> on this hardware. I can't imagine anyone wanting to run 32-bit >> on this hardware, but this is the safe thing to do. > > > > Isn't this work from Mr. Tlb? I have no idea what you mean. >> + if (!err) >> + err = check_knl_erratum(); >> >> if (err_flags_ptr) >> *err_flags_ptr = err ? err_flags : NULL; >> @@ -185,3 +188,32 @@ int check_cpu(int *cpu_level_ptr, int *r >> >> return (cpu.level < req_level || err) ? -1 : 0; >> } >> + >> +int check_knl_erratum(void) > > s/knl/xeon_knl/ ? Nah. I mean we could say xeon_phi_knl, but I don't think it's worth worrying too much about a function called in one place and commented heavily. >> + puts("This 32-bit kernel can not run on this processor due\n" >> + "to a processor erratum. Use a 64-bit kernel, or PAE.\n\n"); > > Give processor name to the scared readers please. Yeah, that's a pretty good idea. I'll be more explicit. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org