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Re: [PATCH] PPC64 elf configure
- From: Richard Henderson <rth at twiddle dot net>
- To: Steve Munroe <sjmunroe at us dot ibm dot com>
- Cc: Roland McGrath <roland at redhat dot com>, Alan Modra <amodra at bigpond dot net dot au>, libc-alpha <libc-alpha at sources dot redhat dot com>
- Date: Wed, 12 Mar 2003 14:00:18 -0800
- Subject: Re: [PATCH] PPC64 elf configure
- References: <OFA12E835A.2FE58930-ON86256CE7.006FD691-86256CE7.0074452A@rchland.ibm.com>
On Wed, Mar 12, 2003 at 03:09:56PM -0600, Steve Munroe wrote:
> It may not be impossible but it is difficult. The ABI allows for the
> possibility of a GOT and small data area as a subset of the TOC, but I
> don't think PPC64 gcc supports SDA. Or at least it's was not getting used
> in the code generated for rtld.c.
This doesn't mean SDA. It means _all_ (data?) symbols can be
addressed without using the GOT. (Certainly for Alpha this is
only true of data symbols.)
> The biggest issue is that we don't support TOCs >64KB and we tend to blow
> the TOC on the larger libs. So putting more stuff into the TOC seems like
> a bad idea.
I think you misunderstand. We're not putting anything into the
TOC at all. We're interested in a 32-bit displacement from the
TOC base register to anything in the data segment. It appears
that PPC64 has the relocations for this, even if gcc does not
support it at the moment.