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Re: Adding cache shape info to powerpc
- From: Steven Munroe <munroesj at linux dot vnet dot ibm dot com>
- To: Benjamin Herrenschmidt <benh at kernel dot crashing dot org>, Tulio Magno Quites Machado Filho <tuliom at linux dot vnet dot ibm dot com>
- Cc: Florian Weimer <fweimer at redhat dot com>, libc-alpha at sourceware dot org, Paul Mackerras <pmac at au1 dot ibm dot com>
- Date: Thu, 01 Dec 2016 09:10:33 -0600
- Subject: Re: Adding cache shape info to powerpc
- Authentication-results: sourceware.org; auth=none
- References: <1471408952.19495.29.camel@kernel.crashing.org> <d350e721-0410-3c3a-86c2-a9f3d90b8f0d@redhat.com> <1471479455.19495.36.camel@kernel.crashing.org>
- Reply-to: munroesj at linux dot vnet dot ibm dot com
On Thu, 2016-08-18 at 10:17 +1000, Benjamin Herrenschmidt wrote:
> On Wed, 2016-08-17 at 10:36 +0200, Florian Weimer wrote:
> > > I've chosen this format. Is that ok with the community ? Can I still use
> > > the same AT_* vector numbers or should I create new ones ?
> >
> > If the old format was in mainline at any point (or in a vendor kernel,
> > but let's hope vendors don't do this anymore), you need to pick new numbers.
> >
> > Do you expect that IFUNC resolvers will need this information?
>
> The old format was only used by other architectures, not powerpc, do I
> still need to pick different numbers in that case ?
>
> As for IFUNC I don't think so but I'll let Steve reply as I believe he
> is the original requestor for the functionality.
>
Ben were are we on this?
This is needed to fix a customer reported bug for lack of
sysconf(_SC_*CACHE_SIZE) support on powerpc.
Adding this information to the cputable and then auxv fits into the
current sysconf infrastructure best.
When we know the AT_ info format and upstream Kernel version we can
update kernel-features.h and enable a sysconf.c fragment to return these
values for powerpc