From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: RE:2Gb Memory lost in 2.6.32.36 - 50G memory, maxmem=50G, 2G used for pagetable, clamping (max:5G) is not helping. Date: Thu, 19 May 2011 12:16:56 -0400 Message-ID: <20110519161656.GA12889@dumpdata.com> References: <20110519144242.GC9854@dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: MaoXiaoyun Cc: jeremy@goop.org, xen devel List-Id: xen-devel@lists.xenproject.org > > What happens if you provide dom0_mem=max:5G to clamp on the size? > > > > Seems nothing different(what is clamp means? ^_^ ) http://en.wikipedia.org/wiki/Clamp_(tool) .. snip.. > Xen: 0000000100000000 - 0000000c6ff09000 (usable) > DMI present. > AMI BIOS detected: BIOS may corrupt low RAM, working around it. > last_pfn = 0xc6ff09 max_arch_pfn = 0x400000000 .. snip.. > xen_commandline : msi=1 iommu=off x2apic=off console=com1,vga com1=115200,8n1 noreboot dom0_mem=max:5G dom0_max_vcpus=4 dom0_vcpus_pin cpuidle=0 cpufreq=none xsave=0 OK, I would have expected your last entry in the E820 to be truncated to 15fe00000, but it is not with the max:5G parameter. Looks like you found a bug - but I am not sure if it is the Xen hypervisor or the E820 parsing code in Linux. Fortunatly for you, I just got my hands on 32G machine so I can work on this. Can you remind me in a week if I you do not see any patches from me?