From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35925) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YTXI5-0002qp-6K for qemu-devel@nongnu.org; Thu, 05 Mar 2015 10:02:25 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YTXI0-0002ho-71 for qemu-devel@nongnu.org; Thu, 05 Mar 2015 10:02:21 -0500 Received: from e28smtp01.in.ibm.com ([122.248.162.1]:59066) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YTXHz-0002h5-K7 for qemu-devel@nongnu.org; Thu, 05 Mar 2015 10:02:16 -0500 Received: from /spool/local by e28smtp01.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 5 Mar 2015 20:32:11 +0530 From: Nikunj A Dadhania In-Reply-To: <874mpz63gx.fsf@blackfin.pond.sub.org> References: <1425546371-15909-1-git-send-email-nikunj@linux.vnet.ibm.com> <87mw3r7obe.fsf@blackfin.pond.sub.org> <87sidj3foq.fsf@abhimanyu.in.ibm.com> <874mpz63gx.fsf@blackfin.pond.sub.org> Date: Thu, 05 Mar 2015 20:32:03 +0530 Message-ID: <87pp8nwkr8.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v3 0/2] Introduce default ram size in MachineClass List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: thuth@linux.vnet.ibm.com, aik@ozlabs.ru, qemu-devel@nongnu.org, agraf@suse.de, qemu-ppc@nongnu.org, marcel.apfelbaum@gmail.com, imammedo@redhat.com Markus Armbruster writes: > Nikunj A Dadhania writes: > >> Markus Armbruster writes: >> >>> Nikunj A Dadhania writes: >>> >>>> Current DEFAULT_RAM_SIZE(128MB) enforced by QEMU would not work for >>>> all machines. Introduce a default_ram_size as part of MachineClass. >>>> >>>> The below patches has following behaviour: >>>> >>>> 1) If the user does not provide "-m" option, machine's default ram >>>> size will be picked. >>>> >>>> 2) In case the user provides memory that is lesser than machine's >>>> default ram size, we upscale the ram_size to machine's >>>> default_ram_size. A warning is displayed for the change that qemu >>>> has done. >>> >>> Please do not "improve" the user's explicit order that way. Either >>> execute the order as is, or reject it as invalid. >> >> If there is consensus for doing this, I can change the patches >> accordingly. >> >> Rejection is also change of behaviour. Because till now, a VM would >> start with any memory size, even if it's less that 128MB >> (default_ram_size). With rejection, all those VMs would fail booting >> displaying the warning. Is this OK? > > I'd stick to "don't reject". Agree, i have already sent v4 with those changes, as there were multiple opinions against changing the behaviour. > Yes, the failure mode is ugly. But protecting the user from it is > also somewhat problematic, because we don't generally know how much > RAM the actual guest requires, and it's an incompatible change. Seems > not worth it. > > Back in 2012, we discussed rejecting RAM size less than 1MiB for PC > machines, because SeaBIOS requires at least that much, and decided > against it. See > http://www.seabios.org/pipermail/seabios/2012-August/004343.html > > If you want to pursue "reject" anyway, please make sure to split this > into two separate patches: one patch to make the default ram size > machine-specific, and another patch to reject user requests for less. > > [...] Thanks, Nikunj