From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36066) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fQGpp-0003ES-28 for qemu-devel@nongnu.org; Tue, 05 Jun 2018 14:37:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fQGpl-0000Gv-TW for qemu-devel@nongnu.org; Tue, 05 Jun 2018 14:37:33 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:45972 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fQGpl-0000FF-M1 for qemu-devel@nongnu.org; Tue, 05 Jun 2018 14:37:29 -0400 Date: Tue, 5 Jun 2018 21:37:25 +0300 From: "Michael S. Tsirkin" Message-ID: <20180605213547-mutt-send-email-mst@kernel.org> References: <20180521163203.26590-1-ross.zwisler@linux.intel.com> <20180521163203.26590-4-ross.zwisler@linux.intel.com> <20180605182243-mutt-send-email-mst@kernel.org> <20180605164205.GA21034@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [qemu PATCH v4 3/4] nvdimm, acpi: support NFIT platform capabilities List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Dan Williams Cc: Ross Zwisler , Eduardo Habkost , linux-nvdimm , Qemu Developers , Stefan Hajnoczi , Igor Mammedov On Tue, Jun 05, 2018 at 11:15:00AM -0700, Dan Williams wrote: > On Tue, Jun 5, 2018 at 9:42 AM, Ross Zwisler > wrote: > > On Tue, Jun 05, 2018 at 06:25:27PM +0300, Michael S. Tsirkin wrote: > >> On Mon, May 21, 2018 at 10:32:02AM -0600, Ross Zwisler wrote: > >> > Add a machine command line option to allow the user to control the Platform > >> > Capabilities Structure in the virtualized NFIT. This Platform Capabilities > >> > Structure was added in ACPI 6.2 Errata A. > >> > > >> > Signed-off-by: Ross Zwisler > >> > >> I tried playing with it and encoding the capabilities is > >> quite awkward. > >> > >> Can we add bits for specific capabilities instead of nvdimm-cap? > >> > >> How about: > >> > >> "cpu-flush-on-power-loss-cap" > >> "memory-flush-on-power-loss-cap" > >> "byte-addressable-mirroring-cap" > > > > Hmmm...I don't like that as much because: > > > > a) It's very verbose. Looking at my current qemu command line few other > > options require that many characters, and you'd commonly be defining more > > than one of these for a given VM. > > > > b) It means that the QEMU will need to be updated if/when new flags are added, > > because we'll have to have new options for each flag. The current > > implementation is more future-proof because you can specify any flags > > value you want. > > > > However, if you feel strongly about this, I'll make the change. > > Straw-man: Could we do something similar with what we are doing in ndctl? > > enum ndctl_persistence_domain { > PERSISTENCE_NONE = 0, > PERSISTENCE_MEM_CTRL = 10, > PERSISTENCE_CPU_CACHE = 20, > PERSISTENCE_UNKNOWN = INT_MAX, > }; > > ...and have the command line take a number where "10" and "20" are > supported today, but allows us to adapt to new persistence domains in > the future. I'm fine with that except can we have symbolic names instead of numbers on command line? -- MST