Re: [Qemu-devel] [Qemu-ppc] RFC: NVRAM for pseries machine

[David Gibson]

On Mon, Sep 24, 2012 at 12:36:33PM +0200, Alexander Graf wrote:
> On 21.09.2012, at 05:08, David Gibson wrote:
[snip]
> > +void spapr_create_nvram(sPAPREnvironment *spapr)
> > +{
> > +    QemuOpts *machine_opts;
> > +    DeviceState *dev;
> > +
> > +    dev = qdev_create(&spapr->vio_bus->bus, "spapr-nvram");
> > +
> > +    machine_opts = qemu_opts_find(qemu_find_opts("machine"), 0);
> > +    if (machine_opts) {
> > +        const char *drivename;
> > +
> > +        drivename = qemu_opt_get(machine_opts, "nvram");
> > +        if (drivename) {
> > +            BlockDriverState *bs;
> > +
> > +            bs = bdrv_find(drivename);
> > +            if (!bs) {
> > +                fprintf(stderr, "No such block device \"%s\" for nvram\n",
> > +                        drivename);
> > +                exit(1);
> 
> I thought you wanted to autogenerate contents in RAM if no drive is available?

We do.  This is the case where the user *has* specified a drive id,
but a drive of that name does not exist.

> > +            }
> > +            qdev_prop_set_drive_nofail(dev, "drive", bs);
> > +        }
> > +    }
> > +
> > +    qdev_init_nofail(dev);
> > +
> > +    spapr->nvram = (sPAPRNVRAM *)dev;
> > +    spapr_rtas_register("nvram-fetch", rtas_nvram_fetch);
> > +    spapr_rtas_register("nvram-store", rtas_nvram_store);
> > +}
> > diff --git a/qemu-config.c b/qemu-config.c
> > index 12eafbb..1cd9a1b 100644
> > --- a/qemu-config.c
> > +++ b/qemu-config.c
> > @@ -619,6 +619,10 @@ static QemuOptsList qemu_machine_opts = {
> >             .name = "mem-merge",
> >             .type = QEMU_OPT_BOOL,
> >             .help = "enable/disable memory merge support",
> > +        }, {
> > +            .name = "nvram",
> > +            .type = QEMU_OPT_STRING,
> > +            .help = "Drive backing persistent NVRAM",
> 
> I like the idea of a machine implemented NVRAM. Maybe we should add
> an -nvram option that does an automatic -drive and -machine
> ...,machine=drive_id for the user :).

Uh, sure, whatever.  I don't really care what syntactic sugar is
added, as long as the basic thing is working.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson