Arnd Bergmann [off-list ref] writes:

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:

quoted

On Friday 20 November 2015 17:23:14 Stephen Boyd wrote:

quoted

This is a respin of a patch series from about a year ago[1]. I

realized

quoted

that we already had most of the code in recordmcount to figure out
where we make calls to particular functions, so recording where
we make calls to the integer division functions should be easy enough
to add support for in the same codepaths. Looking back on the thread
it seems like Mans was thinking along the same lines, although it

wasn't

quoted

obvious to me back then or even over the last few days when I wrote

this.

Shouldn't we start by allowing to build the kernel for -march=armv7ve
on platforms that allow it? That would seem like a simpler change
and likely generate better code for most people, except when you
actually
care about running the same binary kernel on older platforms.

I tried to get a complete list of CPU cores with idiv, lpae and
virtualization support at some point, but I don't remember the
details for all Qualcomm and Marvell cores any more, to create the
complete configuration matrix. IIRC, all CPUs that support
virtualization also do lpae (they have to) and all CPUs that
do lpae also do idiv, but the opposite is not true.

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.

-- 
M?ns Rullg?rd
mans at mansr.com