Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760576Ab0KRVQQ (ORCPT ); Thu, 18 Nov 2010 16:16:16 -0500 Received: from smtp-out.google.com ([74.125.121.35]:30558 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757178Ab0KRVQP (ORCPT ); Thu, 18 Nov 2010 16:16:15 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version:content-type; b=xPlzOhanwVzhBRMgttXgEINmAamRjQqfZ93+/tBY6cabxr5fq/tvlLFEvWQhzhCSIB VikWKeMA5BjSR7JSlbLg== Date: Thu, 18 Nov 2010 13:16:07 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Shaohui Zheng cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, haicheng.li@linux.intel.com, lethal@linux-sh.org, ak@linux.intel.com, shaohui.zheng@linux.intel.com, Yinghai Lu , Haicheng Li Subject: Re: [1/8,v3] NUMA Hotplug Emulator: add function to hide memory region via e820 table. In-Reply-To: <20101118092052.GE2408@shaohui> Message-ID: References: <20101117020759.016741414@intel.com> <20101117021000.479272928@intel.com> <20101118092052.GE2408@shaohui> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2633 Lines: 69 On Thu, 18 Nov 2010, Shaohui Zheng wrote: > > > Index: linux-hpe4/arch/x86/kernel/e820.c > > > =================================================================== > > > --- linux-hpe4.orig/arch/x86/kernel/e820.c 2010-11-15 17:13:02.483461667 +0800 > > > +++ linux-hpe4/arch/x86/kernel/e820.c 2010-11-15 17:13:07.083461581 +0800 > > > @@ -971,6 +971,7 @@ > > > } > > > > > > static int userdef __initdata; > > > +static u64 max_mem_size __initdata = ULLONG_MAX; > > > > > > /* "mem=nopentium" disables the 4MB page tables. */ > > > static int __init parse_memopt(char *p) > > > @@ -989,12 +990,28 @@ > > > > > > userdef = 1; > > > mem_size = memparse(p, &p); > > > - e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1); > > > + e820_remove_range(mem_size, max_mem_size - mem_size, E820_RAM, 1); > > > + max_mem_size = mem_size; > > > > > > return 0; > > > } > > > > This needs memmap= support as well, right? > we did not do the testing after combine both memmap and numa=hide paramter, > I think that the result should similar with mem=XX, they both remove a memory > region from the e820 table. > You've modified the parser for mem= but not memmap= so the change needs additional support for the latter. > > > early_param("mem", parse_memopt); > > > > > > +#ifdef CONFIG_NODE_HOTPLUG_EMU > > > +u64 __init e820_hide_mem(u64 mem_size) > > > +{ > > > + u64 start, end_pfn; > > > + > > > + userdef = 1; > > > + end_pfn = e820_end_of_ram_pfn(); > > > + start = (end_pfn << PAGE_SHIFT) - mem_size; > > > + e820_remove_range(start, max_mem_size - start, E820_RAM, 1); > > > + max_mem_size = start; > > > + > > > + return start; > > > +} > > > +#endif > > > > This doesn't have any sanity checking for whether e820_remove_range() will > > leave any significant amount of memory behind so the kernel will even boot > > (probably should have a guaranteed FAKE_NODE_MIN_SIZE left behind?). > > it should not be checked here, it should be checked by the function who call > e820_hide_mem, and truncate the mem_size with FAKE_NODE_MIN_SIZE. > Your patchset doesn't do that, I'm talking specifically about the amount of memory left behind so that the kernel at least still boots. That seems to be a function of e820_hide_mem() to do some sanity checking so we actually still get a kernel rather than the responsibility of the command-line parser. -- 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/