Re: [PATCH V1 08/29] xen/dts: Don't add a fake property "name" in the device tree

[Julien Grall <julien.grall@linaro.org>]

On 09/06/2013 05:28 PM, Ian Campbell wrote:
> On Wed, 2013-08-28 at 15:47 +0100, Julien Grall wrote:
>> On new Flat Device Tree version, the property "name" may not exist.
>> The property is never used in Xen code except to set the field "name" of
>> dt_device_node.
>>
>> For convenience, remove the fake property. It will save space during the
>> creation of the dom0 FDT.
>
> Is it worth diverging from the Linux code this is based on over this
> though?

If we don't diverge, I need to add some logic in device tree creation to 
know if the "name" property was generated by Xen.

The others solutions was:
    1) Add the logic during device tree creation
    2) Add a boolean to know if the property is a fake

Currently, the "name" property value is replicated in the name field of 
dt_device_node. Except staying close to Linux code, I don't see a good 
reason to create this fake property.

>>
>> Signed-off-by: Julien Grall <julien.grall@linaro.org>
>> ---
>>   xen/common/device_tree.c |   21 +++++++++------------
>>   1 file changed, 9 insertions(+), 12 deletions(-)
>>
>> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
>> index be592d2..07a19ac 100644
>> --- a/xen/common/device_tree.c
>> +++ b/xen/common/device_tree.c
>> @@ -1543,6 +1543,7 @@ static unsigned long __init unflatten_dt_node(const void *fdt,
>>       if ( !has_name )
>>       {
>>           char *p1 = pathp, *ps = pathp, *pa = NULL;
>> +        char *tmp = NULL;
>>           int sz;
>>
>>           while ( *p1 )
>> @@ -1556,25 +1557,21 @@ static unsigned long __init unflatten_dt_node(const void *fdt,
>>           if ( pa < ps )
>>               pa = p1;
>>           sz = (pa - ps) + 1;
>> -        pp = unflatten_dt_alloc(&mem, sizeof(struct dt_property) + sz,
>> -                                __alignof__(struct dt_property));
>> +
>> +        tmp = unflatten_dt_alloc(&mem, sz, 1);
>>           if ( allnextpp )
>>           {
>> -            pp->name = "name";
>> -            pp->length = sz;
>> -            pp->value = pp + 1;
>> -            *prev_pp = pp;
>> -            prev_pp = &pp->next;
>> -            memcpy(pp->value, ps, sz - 1);
>> -            ((char *)pp->value)[sz - 1] = 0;
>> -            dt_dprintk("fixed up name for %s -> %s\n", pathp,
>> -                       (char *)pp->value);
>> +            memcpy(tmp, ps, sz - 1);
>> +            np->name = tmp;
>> +            tmp[sz - 1] = 0;
>> +            dt_dprintk("fixed up name for %s -> %s\n", pathp, np->name);
>>           }
>>       }
>> +
>>       if ( allnextpp )
>>       {
>>           *prev_pp = NULL;
>> -        np->name = dt_get_property(np, "name", NULL);
>> +        np->name = (np->name) ? : dt_get_property(np, "name", NULL);
>>           np->type = dt_get_property(np, "device_type", NULL);
>>
>>           if ( !np->name )
>
>


-- 
Julien Grall