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Re: [PATCHv3] powerpc: ABI change - add HWCAP/HWCAP2/platform info to TCB
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Peter Bergner <bergner at vnet dot ibm dot com>
- Cc: Carlos Eduardo Seo <cseo at linux dot vnet dot ibm dot com>, GNU C Library <libc-alpha at sourceware dot org>, Tulio Machado <tuliom at linux dot vnet dot ibm dot com>, "Steven J. Munroe" <sjmunroe at us dot ibm dot com>, Carlos O'Donell <carlos at redhat dot com>
- Date: Wed, 23 Sep 2015 22:36:50 +0000
- Subject: Re: [PATCHv3] powerpc: ABI change - add HWCAP/HWCAP2/platform info to TCB
- Authentication-results: sourceware.org; auth=none
- References: <4BE991CB-F601-4D63-A416-5991FE870FC4 at linux dot vnet dot ibm dot com> <alpine dot DEB dot 2 dot 10 dot 1509232114070 dot 10585 at digraph dot polyomino dot org dot uk> <B650304C-6207-46AC-B6A8-FA29959B305D at linux dot vnet dot ibm dot com> <alpine dot DEB dot 2 dot 10 dot 1509232141250 dot 10585 at digraph dot polyomino dot org dot uk> <1443046986 dot 23503 dot 68 dot camel at otta>
On Wed, 23 Sep 2015, Peter Bergner wrote:
> The idea is that applications will use the builtins supplied by GCC
> (and other compilers) and will not access this info directly.
> In GCC, my plan is to first add a configure test looking for the
> symbol and if it doesn't exist, then I'll make the builtins return
(Please make that configure test respect --with-glibc-version so that the
results can be correct when a bootstrap compiler is configured without
pre-existing glibc.)
> false for all queries. If it does exist during configure, I'll emit
> code to load/test the TCB entries, but I'll also emit a data reference
> to the symbol which will cause a linker/loader error in the event the
> user attempts to link/run against an old glibc.
In that case, the name should still be in the reserved namespace, and the
entry in the Versions file should have a comment explaining this use by
GCC builtins (all reserved-namespace entries in Versions files outside of
GLIBC_PRIVATE should have comments explaining why they are needed).
--
Joseph S. Myers
joseph@codesourcery.com