From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38023) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YTXNt-0008B8-KX for qemu-devel@nongnu.org; Thu, 05 Mar 2015 10:08:29 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YTXNe-0005Gv-8K for qemu-devel@nongnu.org; Thu, 05 Mar 2015 10:08:21 -0500 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:51029) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YTXNd-0005GD-Jn for qemu-devel@nongnu.org; Thu, 05 Mar 2015 10:08:06 -0500 Received: from /spool/local by e28smtp08.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 5 Mar 2015 20:38:02 +0530 From: Nikunj A Dadhania In-Reply-To: References: <1425546371-15909-1-git-send-email-nikunj@linux.vnet.ibm.com> <87mw3r7obe.fsf@blackfin.pond.sub.org> <87sidj3foq.fsf@abhimanyu.in.ibm.com> Date: Thu, 05 Mar 2015 20:37:57 +0530 Message-ID: <87mw3rwkhe.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: Peter Maydell Cc: Thomas Huth , Alexey Kardashevskiy , Markus Armbruster , Alexander Graf , QEMU Developers , "qemu-ppc@nongnu.org" , marcel.apfelbaum@gmail.com, Igor Mammedov Peter Maydell writes: > On 5 March 2015 at 19:24, Nikunj A Dadhania wrote: >> 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? > > No. Not all of the machines we emulate are modern machines with > gigabytes of memory -- some are very small boards which might > really only have 64K of RAM. If the user asks for 64K you should > do what they ask. > > If what you want is to reject user specified memory sizes which > are too small, this is a "minimum RAM size", which is different > from "default RAM size". It would also be nice to have a > "maximum RAM size", so we can avoid weird failures if the user > asks for 1GB on a board which only has 256MB of space for RAM > in its address map. Yes, [min,max]_ram_size is more appropriate. At present, I have sent a v4 without changing the default behaviour when user has provided an option. > Somebody may be along shortly to complain that this doesn't account > for machines where you can only add RAM one DRAM stick at a time > and so 64MB, 128MB and 256MB might all be valid but 100MB not. Yes, and these would help memory hotplug as well. > At least, that's what happened a few years ago when I tried to > suggest something like these per-board properties... > > -- PMM Regards Nikunj