From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Travis Date: Fri, 25 Apr 2008 12:50:49 +0000 Subject: Re: [2.6 patch] ia64: let NUMA select SMP Message-Id: <4811D3A9.4060602@sgi.com> List-Id: References: <1FE6DD409037234FAB833C420AA843EC012F9EF0@orsmsx424.amr.corp.intel.com> <20080425001652.GD18854@cs181133002.pp.htv.fi> <1FE6DD409037234FAB833C420AA843EC012F9F55@orsmsx424.amr.corp.intel.com> <20080425004139.GE18854@cs181133002.pp.htv.fi> In-Reply-To: <20080425004139.GE18854@cs181133002.pp.htv.fi> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Adrian Bunk Cc: "Luck, Tony" , torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, Russ Anderson Adrian Bunk wrote: > On Thu, Apr 24, 2008 at 05:25:06PM -0700, Luck, Tony wrote: >>>> Build fix for CONFIG_NUMA=y && CONFIG_SMP=n >>>> ... >>> Why is this an allowed configuration on ia64? >> It shows up in allnoconfig ... probably because some >> bit of Kconfig forces NUMA=y. > > allnoconfig results in CONFIG_IA64_GENERIC=y, which in turn selects NUMA. > > What about the patch below instead? > >> I can't imagine that it is ever a useful combination ... except to >> find places in the code where people have: Though highly unlikely, it is possible to have multiple memory nodes without having multiple cpus -- at least in theory. In this specific case it's nonsensical because the scheduler is grouping cpus by node. Thanks, Mike >> >> #if defined(CONFIG_SMP) >> ... >> #else >> >> #if defined(CONFIG_NUMA) // !!! SMP=n, NUMA code??? >> ... >> #endif >> #endif >> >> >> Which is what happened, and is being fixed, here. > > If it isn't a useful combination such code makes no sense. > >> -Tony > > cu > Adrian > > > <-- snip --> > > > CONFIG_NUMA=y, CONFIG_SMP=n isn't a useful combination, so let NUMA > select SMP. > > Signed-off-by: Adrian Bunk > > --- > a94d43a82a3c5a95c82b9688e5adebca6dcb7acb diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig > index cd13e13..19e8167 100644 > --- a/arch/ia64/Kconfig > +++ b/arch/ia64/Kconfig > @@ -387,6 +387,7 @@ config NUMA > bool "NUMA support" > depends on !IA64_HP_SIM && !FLATMEM > default y if IA64_SGI_SN2 > + select SMP > select ACPI_NUMA if ACPI > help > Say Y to compile the kernel to support NUMA (Non-Uniform Memory >