On Mon, Aug 22, 2011 at 8:56 AM, Michael Matz <m...@suse.de> wrote:
> Hi,
>
> On Mon, 22 Aug 2011, H.J. Lu wrote:
>
>> >> Oh, I thought it was data initialized by the constructor ...
>> >
>> > Sriramans patch right now has a function __cpu_indicator_init which is
>> > called from (adhoc constructed) ctors and that initializes variables
>> > __cpu_model and __cpu_features ;-) There's no __cpu_indicator symbol :)
>> >
>> > I think the whole initializer function and the associated data blobs have
>> > to sit in static libgcc and be hidden. By that all shared modules
>> > will have their own copies of the model and features (and the initializer
>> > function) so there won't be issues with copy relocs, or cross shared lib
>> > calls while relocating the modules. Dynamically they will contain the
>> > same data always, but it's not many bytes, and only modules making use of
>> > this facility will pay it.
>> >
>> > The initializer function has to be callable from pre-.init contexts, e.g.
>> > ifunc dispatchers. And to make life easier there should be one ctor
>> > function calling this initializer function too, so that normal code can
>> > rely on it being already called saving one check.
>> >
>>
>> It sounds more complicated than necessary. Why not just do it
>> on demand like glibc does?
>
> Ehm, the only difference would be to not have a ctor in libgcc that looks
> like so:
>
> void __attribute__((constructor)) bla(void)
> {
> __cpu_indicator_init ();
> }
>
> I don't see any complication.?
>
Order of constructors. A constructor may call functions
which use __cpu_indicator.
--
H.J.
