From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56891) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z5MCR-0000j1-Hg for qemu-devel@nongnu.org; Wed, 17 Jun 2015 18:52:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z5MCQ-0001Sb-El for qemu-devel@nongnu.org; Wed, 17 Jun 2015 18:52:51 -0400 Received: from mail-la0-x22b.google.com ([2a00:1450:4010:c03::22b]:35509) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z5MCQ-0001N2-0P for qemu-devel@nongnu.org; Wed, 17 Jun 2015 18:52:50 -0400 Received: by labko7 with SMTP id ko7so43318901lab.2 for ; Wed, 17 Jun 2015 15:52:47 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: From: Andrey Korolyov Date: Thu, 18 Jun 2015 01:52:26 +0300 Message-ID: Content-Type: text/plain; charset=UTF-8 Subject: Re: [Qemu-devel] incorrect memory size inside vm List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vasiliy Tolstov Cc: libvir-list , "qemu-devel@nongnu.org" On Thu, Jun 18, 2015 at 1:44 AM, Vasiliy Tolstov wrote: > 2015-06-18 1:40 GMT+03:00 Andrey Korolyov : >> >> Yes, but I`m afraid that I don`t fully understand why do you need this >> when pure hotplug mechanism is available, aside may be nice memory >> stats from balloon and easy-to-use deflation. Just populate a couple >> of static dimms with small enough 'base' e820 memory and use balloon >> on this setup, you`ll get the reserved memory footprint as small as it >> would be in setup with equal overall amount of memory populated via >> BIOS. For example, you may use -m 128 ... {handful amount of memory >> placed in memory slots} setup to achieve the thing you want. > > > I have debian wheezy guests with 3.4 kernels (or 3.2..) and many > others like 32 centos 6, opensue , ubuntu, and other. > Does memory hotplug works with this distros (kernels)? > Whoosh... technically it is possible but it would be an incompatible fork for the upstreams for both SeaBIOS and Qemu, because the generic way of plugging DIMMs in is available down to at least generic 2.6.32. Except may be Centos where broken kabi would bring great consequences, it may be better to just provide a backport repository with newer kernels, but it doesn`t sound very optimistic. For the history records, the initial hotplug support proposal provided by Vasilis Liaskovitis a couple of years ago worked in an exact way you are suggesting to, but its resurrection would mean emulator and rom code alteration, as I said above.