Re: [PATCH 1/9] binutils,gas,opcodes.elf: remove never used SPARC features and upgrade hwcaps.

[jose dot marchesi at oracle dot com (Jose E. Marchesi)]

    From: jose.marchesi@oracle.com (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
    >     features.
    > 
    > 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.