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Re: [PATCH 1/9] binutils,gas,opcodes.elf: remove never used SPARC features and upgrade hwcaps.
- From: jose dot marchesi at oracle dot com (Jose E. Marchesi)
- To: David Miller <davem at davemloft dot net>
- Cc: binutils at sourceware dot org
- Date: Tue, 07 Oct 2014 14:39:26 +0200
- Subject: Re: [PATCH 1/9] binutils,gas,opcodes.elf: remove never used SPARC features and upgrade hwcaps.
- Authentication-results: sourceware.org; auth=none
- References: <1412266782-14873-2-git-send-email-jose dot marchesi at oracle dot com> <20141004 dot 201231 dot 1670791506145168102 dot davem at davemloft dot net> <87ppe64rs9 dot fsf at oracle dot com> <20141005 dot 164505 dot 2188245293096608776 dot davem at davemloft dot net>
From: firstname.lastname@example.org (Jose E. Marchesi)
Date: Sun, 05 Oct 2014 14:36:38 +0200
> > This patch removes support from GNU binutils for the following SPARC
> > features, which were never released to the public or implemented:
> > - The transactional memory instructions of the cancelled Rock
> > processor (UltraSPARC-AT10): CHKPT and COMMIT.
> > - The %cps ancillary state register, also introduced in the
> > UltraSPARC-AT10, along with the associated rd/wr instructions.
> > - The RANDOM instruction.
> These hw capability ELF flags are encoded into binaries and you
> therefore cannot just repurpose them however you like. You will
> therefore have to allocate new capability flag values for these
> I agree in that it is funny to redefine bits like that in a public
> interface, but allocating other bits for the JF* caps would imply to
> diverge from Solaris. Is that what you want?
The problem is that if readelf sees the bits set in the binary (and
I know for a fact there are binaries out there with them set) it will
report the wrong value.
So yes that means we must not repeat what Solaris's has done.
Ok. I am preparing a second version of the patch set that keeps the old
hwcaps for backwards compatibility while bits for the new FJATHHPC,
FJDES and FJAES capabilities are allocated in the HWCAPS2 word.