[RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions

Arnd Bergmann
2015-11-21T23:14:14Z

On Saturday 21 November 2015 22:11:36 M?ns Rullg?rd wrote:
> Arnd Bergmann <arnd@arndb.de> writes:
> > On Saturday 21 November 2015 20:45:38 M?ns Rullg?rd wrote:
> >> On 21 November 2015 20:39:58 GMT+00:00, Arnd Bergmann <arnd@arndb.de> wrote:
> >>
> >> The ARM ARM says anything with virt has idiv, lpae doesn't matter.
> >
> > Ok, and anything with virt also has lpae by definition. The question is
> > whether we care about using idiv on cores that do not have lpae, or that
> > have neither lpae nor virt.
>
> The question is, are there any such cores? GCC doesn't know of any, but
> then it's missing most non-ARM designs.

Exactly. Stephen should be able to find out about the Qualcomm cores,
and http://comments.gmane.org/gmane.linux.ports.arm.kernel/426289 has
some information about the others:
* Brahma-B15 supports all three.
* Dove (PJ4) reports idiv only in thumb mode, which I'm tempted to ignore
for the kernel, as it supports neither lpae nor idiva.
* Armada 370/XP (PJ4B) reports support for idiva and idivt, but according to
https://groups.google.com/a/dartlang.org/forum/#!topic/reviews/9wvsJvq0YYY
that may be a lie.
* According to the same source, Krait fails to report idiva and idivt,
but supports both anyway. However, I found reports on the web where
/proc/cpuinfo correctly contains the flags on the same SoC (APQ8064)
that was mentioned there, so maybe they were just running an old
kernel.

Arnd