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

On Saturday 21 November 2015 22:11:36 M?ns Rullg?rd wrote:

Arnd Bergmann [off-list ref] writes:

quoted

On Saturday 21 November 2015 20:45:38 M?ns Rullg?rd wrote:

quoted

On 21 November 2015 20:39:58 GMT+00:00, Arnd Bergmann [off-list ref] 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