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

From Måns Rullgård <mans@mansr.com>
Newsgroups linux.kernel
Subject Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions
Date 2015-11-21 23:20 +0100
Message-ID <qxoFI-34f-9@gated-at.bofh.it> (permalink)
References <qx5a1-6MK-1@gated-at.bofh.it> <qxngC-1ZX-5@gated-at.bofh.it> <qxngC-1ZX-3@gated-at.bofh.it> <qxnzY-2lX-9@gated-at.bofh.it>
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Arnd Bergmann <arnd@arndb.de> writes:

> On Saturday 21 November 2015 20:45:38 Måns Rullgård wrote:
>> On 21 November 2015 20:39:58 GMT+00:00, Arnd Bergmann <arnd@arndb.de> wrote:
>> >On Friday 20 November 2015 17:23:14 Stephen Boyd wrote:
>> >> This is a respin of a patch series from about a year ago[1]. I
>> >realized
>> >> 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
>> >> 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.

-- 
Måns Rullgård
mans@mansr.com
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[RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-21 02:30 +0100
  [RFC/PATCH 2/3] recordmcount: Record locations of __aeabi_{u}idiv() calls on ARM Stephen Boyd <sboyd@codeaurora.org> - 2015-11-21 02:30 +0100
    Re: [RFC/PATCH 2/3] recordmcount: Record locations of  __aeabi_{u}idiv() calls on ARM Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-21 11:20 +0100
      Re: [RFC/PATCH 2/3] recordmcount: Record locations of  __aeabi_{u}idiv() calls on ARM Steven Rostedt <rostedt@goodmis.org> - 2015-11-23 22:00 +0100
      Re: [RFC/PATCH 2/3] recordmcount: Record locations of  __aeabi_{u}idiv() calls on ARM Stephen Boyd <sboyd@codeaurora.org> - 2015-11-23 22:00 +0100
        Re: [RFC/PATCH 2/3] recordmcount: Record locations of  __aeabi_{u}idiv() calls on ARM Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-23 22:10 +0100
          Re: [RFC/PATCH 2/3] recordmcount: Record locations of  __aeabi_{u}idiv() calls on ARM Stephen Boyd <sboyd@codeaurora.org> - 2015-11-23 22:20 +0100
            Re: [RFC/PATCH 2/3] recordmcount: Record locations of  __aeabi_{u}idiv() calls on ARM Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-23 22:40 +0100
              Re: [RFC/PATCH 2/3] recordmcount: Record locations of  __aeabi_{u}idiv() calls on ARM Stephen Boyd <sboyd@codeaurora.org> - 2015-11-24 02:10 +0100
  [RFC/PATCH 1/3] scripts: Allow recordmcount to be used without tracing enabled Stephen Boyd <sboyd@codeaurora.org> - 2015-11-21 02:30 +0100
  [RFC/PATCH 3/3] ARM: Replace calls to __aeabi_{u}idiv with udiv/sdiv instructions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-21 02:30 +0100
    Re: [RFC/PATCH 3/3] ARM: Replace calls to __aeabi_{u}idiv with udiv/sdiv instructions Måns Rullgård <mans@mansr.com> - 2015-11-21 13:00 +0100
      Re: [RFC/PATCH 3/3] ARM: Replace calls to __aeabi_{u}idiv with  udiv/sdiv instructions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-23 22:00 +0100
        Re: [RFC/PATCH 3/3] ARM: Replace calls to __aeabi_{u}idiv with udiv/sdiv instructions Måns Rullgård <mans@mansr.com> - 2015-11-23 22:00 +0100
          Re: [RFC/PATCH 3/3] ARM: Replace calls to __aeabi_{u}idiv with  udiv/sdiv instructions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-23 22:20 +0100
  Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Måns Rullgård <mans@mansr.com> - 2015-11-21 21:50 +0100
    Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-21 22:10 +0100
      Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Måns Rullgård <mans@mansr.com> - 2015-11-21 23:20 +0100
        Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-22 00:20 +0100
          Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-22 00:30 +0100
            Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Peter Maydell <peter.maydell@linaro.org> - 2015-11-22 14:40 +0100
              Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-22 20:30 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Måns Rullgård <mans@mansr.com> - 2015-11-22 20:40 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-22 20:50 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-22 21:00 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-22 21:10 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-22 21:40 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Måns Rullgård <mans@mansr.com> - 2015-11-22 21:50 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-22 22:20 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Nicolas Pitre <nicolas.pitre@linaro.org> - 2015-11-23 03:40 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-23 09:20 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv  library functions Christopher Covington <cov@codeaurora.org> - 2015-11-23 15:20 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-23 16:40 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-23 21:40 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-23 22:30 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-23 22:40 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-23 23:00 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-24 00:20 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-24 11:20 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Måns Rullgård <mans@mansr.com> - 2015-11-24 13:20 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-24 14:50 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-25 03:00 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-25 08:30 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-24 01:20 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-24 10:00 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-24 11:40 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-24 11:50 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Måns Rullgård <mans@mansr.com> - 2015-11-24 13:20 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Måns Rullgård <mans@mansr.com> - 2015-11-24 13:30 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Måns Rullgård <mans@mansr.com> - 2015-11-24 15:10 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-24 15:10 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-24 13:30 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-24 11:50 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-24 21:10 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-24 21:40 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-24 22:20 +0100
                Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library  functions Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-24 11:40 +0100
  Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Arnd Bergmann <arnd@arndb.de> - 2015-11-21 21:50 +0100

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