Hi!
On Thu, 29 Jun 2017, James Le Cuirot wrote:
> > No. Alpha is little endian.
>
> Wikipedia says it is bi. tc-native() reports alpha* as big so I guess
> that's the only variant we support? Then again, this page says it is
> usually little. Is tc-native() wrong?
>
> https://kernelnewbies.org/EndianIssues
For the purposes of explanation, let's distinguish
Alpha-the-processor from Alpha-the-systems here.
Yes, the AtP can be switched between big- and little-endianess.
AtS can't. That is, once built, hardware-wise, it has to be
either, but can never switch. Even the firmware has to be
different between LE and BE systems.
There are a lot of LE Alpha systems, in essence, everything that
was ever sold as an Alpha system by DEC, Compaq, HP and sundry
others (like Samsung, who made the UP1500 and related systems).
As a guideline: if it ever ran True64, OSF/1 or digital alpha
UNIX, it is little-endian.
The machines that run Alpha CPUs in big-endian mode are
exclusively Cray supercomputers like the Cray T3D and T3E series.
Linux only ever supported parts of the former group (e.g. the
high-end Alpha server GS1280 series from Compaq is definitely not,
despite running in little-endian mode). The big endian Crays were
never even close to be supported.
tl;dr: Alpha is little-endian only for (our) practical purposes.
Regards,
Tobias
PS: There may be obscure one-off or developer boards for Alphas
which can switch, but the tl;dr still stands.
--
Sent from aboard the Culture ship
GSV (Range Class) Ethics Gradient
