[Linux-ia64] Re: ia64 cache flushing?

David Mosberger
2002-12-17T03:50:53Z

>>>>> On Mon, 16 Dec 2002 19:42:51 -0800, Richard Henderson <rth@twiddle.net> said:

Richard> On Mon, Dec 16, 2002 at 06:15:28PM -0800, David Mosberger
Richard> wrote:
>> For someone who cares about modules and ia64 performance: you
>> might want to consider to use "brl" in the PLT stub instead of
>> the standardized code sequence.

Richard> You'll have to figure out how to find the plt stub though.
Richard> It's not marked in any way. The only thing you get a
Richard> pointer to is the .IA_64.pltoff entry.

Richard> For userland, the .plt stub has to use an indirect branch
Richard> because the first invocation goes through the dynamic
Richard> linker. Then we update the .pltoff entry and so subsequent
Richard> calls go direct to the target.

I assume you do early binding of the PLTs for kernel modules, right?
If so, patching the PLT code stub is trivial (even in user-land you
could do code patching, but that's obviously (a) not so trivial for
multi-threaded programs and (b) hurts sharing).

For user-level land, we should offer PLT-stub-inlining, but we
discussed this in private already...

--david