Re: [PATCH v2] ppc/pnv.c: fix "system-id" FDT when -uuid is set

[Daniel Henrique Barboza]

On 12/6/21 21:09, David Gibson wrote:
> On Mon, Dec 06, 2021 at 10:02:53AM -0300, Daniel Henrique Barboza wrote:
> > Setting -uuid in the pnv machine does not work:
> >
> > ./qemu-system-ppc64 -machine powernv8,accel=tcg  -uuid 
> > 7ff61ca1-a4a0-4bc1-944c-abd114a35e80
> > qemu-system-ppc64: error creating device tree: (fdt_property_string(fdt, 
> > "system-id", buf)): FDT_ERR_BADSTATE
> >
> > This happens because we're using "fdt_property_string" to retrieve a
> > "system-id" attribute that does not exist, instead of using
> > fdt_setprop_string() to create a "system-id" attribute with the uuid
> > provided via command line.
>
> Fix is correct but this description isn't really accurate.
> fdt_property_string() is a "sequential write" function, only used when
> you're building a new DT up from scratch, which is an entirely
> different mode from read/write access to an existing tree.  Using when
> the tree is in read-write state will cause an immediate BADSTATE
> error; whether the property exists already or not is irrelevant.
>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

Thanks for the explanation. I'll send a v3 fixing the commit msg.


Daniel

> > Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> > ---
> >
> > changes from v1:
> > - fixed typo in commit title
> >
> >
> >   hw/ppc/pnv.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
> > index 32ab8071a4..9e532caa9f 100644
> > --- a/hw/ppc/pnv.c
> > +++ b/hw/ppc/pnv.c
> > @@ -552,7 +552,7 @@ static void *pnv_dt_create(MachineState *machine)
> >       buf =  qemu_uuid_unparse_strdup(&qemu_uuid);
> >       _FDT((fdt_setprop_string(fdt, 0, "vm,uuid", buf)));
> >       if (qemu_uuid_set) {
> > -        _FDT((fdt_property_string(fdt, "system-id", buf)));
> > +        _FDT((fdt_setprop_string(fdt, 0, "system-id", buf)));
> >       }
> >       g_free(buf);
> >