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Re: ppc64 vDSO in mainline
- From: Benjamin Herrenschmidt <benh at kernel dot crashing dot org>
- To: Roland McGrath <roland at redhat dot com>
- Cc: Steve Munroe <sjmunroe at us dot ibm dot com>, Alan Modra <amodra at bigpond dot net dot au>, libc-alpha at sources dot redhat dot com
- Date: Thu, 24 Mar 2005 12:53:48 +1100
- Subject: Re: ppc64 vDSO in mainline
- References: <200503240114.j2O1EeCO030834@magilla.sf.frob.com>
On Wed, 2005-03-23 at 17:14 -0800, Roland McGrath wrote:
> I'd really like to see you do the prototyping step before getting into the
> fancy business. This is was I asked for before. Take gettimeofday, the
> favorite first example. Do this by writing a powerpc/gettimeofday.c that
> does a lookup using _dl_vsym and caches the result in a static variable.
> Use whatever magic you need to handle the missing descriptor.
>
> Steve alluded to problems doing a symbol lookup but didn't give any details.
> Like I said before, make that work, and ask here for help in how to do it,
> before moving on to hairy ld.so hacks. One thing at a time.
Sure, will do, I was just trying to explain Steve what was the long term
ideas we had around those issues. I do have some hacks somewhere that I
need to dig out that I did for testing the implementation. I was
basically linking the app against the vDSO to get the symbol address
(that part need to be fixed obviously) and then had an inline asm to do
the branch without TOC reloads etc... I'll dig that out after easter
vacations.
Ben.