Fat arm support

Torbjörn Granlund tg at gmplib.org
Sun Jan 18 21:09:49 UTC 2015

nisse at lysator.liu.se (Niels Möller) writes:

  Hmm, I had a quick look in asm/hwcap.h and the getauxval manpage. As far
  as I see, this doesn't provide any information on the architecture
  version. How do you get that, is there some other type constant for
  getauxval which I'm missing? In /proc/cpuinfo, one can look for the "CPU
  architecture:" line.

The CPU architecture line is not correct on any Linux version I have.
On v7-a it says simply 7, which is not an existing architecture.  I
wonder how it treats say 6 and 6t2.

The reliable way of deducing architecture is via "CPU part".
Unfortunately, as new parts appear one will need tweaking.

Perhaps one could deduce at least v6 from "CPU architecture" "7".

  E.g, testing availability of the uxtb instruction, available in ARMv6
  and later if I've understood it correctly. (I'm taking as example an
  instruction used in Nettle, but from looking at the diretories under
  gmp/mpn/arm, I think arch-version tests are needed in GMP too).
We primarily look at the "CPU part" field, see config.guess.

Please encrypt, key id 0xC8601622

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