Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754892Ab0KUApU (ORCPT ); Sat, 20 Nov 2010 19:45:20 -0500 Received: from smtp-out.google.com ([216.239.44.51]:6795 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753445Ab0KUApS (ORCPT ); Sat, 20 Nov 2010 19:45:18 -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=DZ+I+RcpBX2z24IIgAs62PcMbBsFCN9r0v+H02D6hSAZZ69cYnY68MPaDjX+J4HOTb TO4/68vDxtk/JvyV36Iw== Date: Sat, 20 Nov 2010 16:45:06 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Shaohui Zheng cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, haicheng.li@linux.intel.com, lethal@linux-sh.org, Andi Kleen , Yinghai Lu , Haicheng Li Subject: Re: [1/8,v3] NUMA Hotplug Emulator: add function to hide memory region via e820 table. In-Reply-To: <20101119001218.GA3327@shaohui> Message-ID: References: <20101117020759.016741414@intel.com> <20101117021000.479272928@intel.com> <20101118092052.GE2408@shaohui> <20101119001218.GA3327@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: 2669 Lines: 63 On Fri, 19 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. > > > > the parser for mem= is not modified, the changed parser is numa=, I add a addtional > option numa=hide=. > The above hunk is modifying the x86 parser for the mem= parameter. > > 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. > > How much memory is enough to make sure the kernel can still boot, it is very > hard to measure. it is almost impossible to get the exact data. I try to leave very > few memory to kernel(hide most memory with numa=hide), it cause a panic directly. > > I have no idea about it, do you have any suggestions? > Yes, I think we should use FAKE_NODE_MIN_SIZE to represent the smallest node that may be added and so the appropriate behavior or e820_hide_mem() would be to leave at least this quantity behind for the kernel to be loaded. -- 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/