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

[Daniel Henrique Barboza <danielhb413@gmail.com>]

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);
>>   
>