10:21 p.m.
On Tue, Jun 5, 2018 at 3:07 PM, Ross Zwisler
<ross.zwisler(a)linux.intel.com> wrote:
On Tue, Jun 05, 2018 at 09:37:25PM +0300, Michael S. Tsirkin wrote:
> On Tue, Jun 05, 2018 at 11:15:00AM -0700, Dan Williams wrote:
> > On Tue, Jun 5, 2018 at 9:42 AM, Ross Zwisler
> > <ross.zwisler(a)linux.intel.com> 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 <ross.zwisler(a)linux.intel.com>
> > >>
> > >> 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
Okay, we can move to the symbolic names. Do you want them to be that long, or
would:
nvdimm-cap-cpu
nvdimm-cap-mem-ctrl
nvdimm-cap-mirroring
Wait, why is mirroring part of this?
I was thinking this option would be:
--persistence-domain={cpu,mem-ctrl}
...and try not to let ACPI specifics leak into the qemu command line
interface. For example PowerPC qemu could have a persistence domain
communicated via Open Firmware or some other mechanism.
or something be better?