Re: [Qemu-devel] [PATCH memory v2 3/3] memory: Lazy init name from QOM name as needed

[Peter Crosthwaite]

On Fri, Aug 29, 2014 at 12:06 AM, Paolo Bonzini <address@hidden> wrote:
> Il 26/08/2014 05:10, Peter Crosthwaite ha scritto:
>> To support name retrieval of MemoryRegions that were created
>> dynamically (that is, not via memory_region_init and friends). We
>> cache the name in MemoryRegion's state as
>> object_get_canonical_path_component mallocs the returned value
>> so it's not suitable for direct return to callers. Memory already
>> frees the name field, so this will be garbage collected along with
>> the MR object.
>>
>> Signed-off-by: Peter Crosthwaite <address@hidden>
>> ---
>>
>>  memory.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/memory.c b/memory.c
>> index 42317a2..fc16e5f 100644
>> --- a/memory.c
>> +++ b/memory.c
>> @@ -914,7 +914,6 @@ void memory_region_init(MemoryRegion *mr,
>>      if (size == UINT64_MAX) {
>>          mr->size = int128_2_64();
>>      }
>> -    mr->name = g_strdup(name);
>
> This causes a bunch of [0] to appear in the "info mtree" output.
> They're a bit ugly, so I'm removing this line for now.
>

Yeh, so a solution to that was to patch qom to drop the [*] for
singletons added via arrayified property adders. One possible semantic
that I can think of is the 0th element always has a property alias so
that foo and foo[0] mean the same thing. This tricky part is, when
"[1]" comes along the preferred name (the canonical path) for the 0th
element should switch from "foo" to "foo[0]". Is it sane to switch
child and alias strings for "[0]" when "[1]" comes along?

Regards,
Peter

> Paolo
>
>>      if (name) {
>>          object_property_add_child_array(owner, name, OBJECT(mr));
>> @@ -1309,6 +1308,10 @@ uint64_t memory_region_size(MemoryRegion *mr)
>>
>>  const char *memory_region_name(const MemoryRegion *mr)
>>  {
>> +    if (!mr->name) {
>> +        ((MemoryRegion *)mr)->name =
>> +            object_get_canonical_path_component(OBJECT(mr));
>> +    }
>>      return mr->name;
>>  }
>>
>>
>
>