Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932104Ab2BJAAs (ORCPT ); Thu, 9 Feb 2012 19:00:48 -0500 Received: from mail-bk0-f46.google.com ([209.85.214.46]:34916 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758487Ab2BJAAr convert rfc822-to-8bit (ORCPT ); Thu, 9 Feb 2012 19:00:47 -0500 MIME-Version: 1.0 In-Reply-To: <20120209080648.GI18387@elte.hu> References: <1328209817-18913-1-git-send-email-bp@alien8.de> <20120202193702.GA9502@elliptictech.com> <20120202202427.GA2234@x1.osrc.amd.com> <20120203191801.GA2846@x1.osrc.amd.com> <20120207095746.GH15359@elte.hu> <20120208101956.GA1772@x1.osrc.amd.com> <20120209080648.GI18387@elte.hu> Date: Thu, 9 Feb 2012 20:00:45 -0400 Message-ID: Subject: Re: MCE, AMD: Hide smp-only code around CONFIG_SMP From: Kevin Winchester To: Ingo Molnar Cc: Borislav Petkov , Nick Bowler , Randy Dunlap , "H. Peter Anvin" , Thomas Gleixner , LKML Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1753 Lines: 48 On 9 February 2012 04:06, Ingo Molnar wrote: > > * Borislav Petkov wrote: > >> +++ b/arch/x86/include/asm/smp.h >> @@ -33,8 +33,15 @@ static inline bool cpu_has_ht_siblings(void) >> >> ?DECLARE_PER_CPU(cpumask_var_t, cpu_sibling_map); >> ?DECLARE_PER_CPU(cpumask_var_t, cpu_core_map); >> -/* cpus sharing the last level cache: */ >> + >> +#ifdef CONFIG_SMP >> +/* CPUs sharing the last level cache: */ >> ?DECLARE_PER_CPU(cpumask_var_t, cpu_llc_shared_map); >> +#else >> +static DECLARE_BITMAP(cpu_llc_shared_bits, NR_CPUS) __read_mostly = { [0] = 1UL }; >> +static struct cpumask *const cpu_llc_shared_map = to_cpumask(cpu_llc_shared_bits); >> +#endif > > Why not just expose it like on SMP? > > We want to *reduce* the specialness of UP, not increase it - one > more word of .data and .text does not matter much - UP is > becoming more and more an oddball, rarely tested config. By the > time these changes hit any real boxes it will be even more > oddball. > It seems that cpu_llc_shared_map is actually defined in arch/x86/kernel/smpboot.c, which is not compiled/linked for UP builds. Is there an equivalent file for UP that could be used instead, or could the: DEFINE_PER_CPU(cpumask_var_t, cpu_llc_shared_map); be moved to some other file? Generally, it sounds like you might approve of an eventual merging of the boot paths for SMP and UP. Is that true? I wonder how much work that would be. That would really reduce the specialness of UP. -- Kevin Winchester -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/