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

From Stephen Boyd <sboyd@codeaurora.org>
Newsgroups linux.kernel
Subject Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions
Date 2015-11-23 21:40 +0100
Message-ID <qy641-6NZ-5@gated-at.bofh.it> (permalink)
References <qx5a1-6MK-1@gated-at.bofh.it> <qxUvV-7DO-17@gated-at.bofh.it> <qy08i-2R4-15@gated-at.bofh.it> <qy1nH-3Ia-1@gated-at.bofh.it>
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On 11/23, Arnd Bergmann wrote:
> On Monday 23 November 2015 09:14:39 Christopher Covington wrote:
> > On 11/23/2015 03:15 AM, Arnd Bergmann wrote:
> > > On Sunday 22 November 2015 21:36:45 Nicolas Pitre wrote:
> > >> On Sun, 22 Nov 2015, Arnd Bergmann wrote:
> > > 
> > > Ok, thanks a lot! So the reporting in /proc/cpuinfo clearly matches
> > > the actual features, and we can just treat this as no LPAE / no IDIV
> > > for kernel compilation, as nobody ever seems to use THUMB2_KERNEL
> > > in practice.
> > > 
> > > PJ4-MP is like Cortex-A15/A7/A12/A17 and supports both IDIV and LPAE,
> > > which leaves the question whether Scorpion or Krait do the same as
> > > well, or whether they are outliers and need a special configuration.
> > 
> > LPAE is only supported in the Krait 450.
> > 
> > http://www.anandtech.com/show/7537/qualcomms-snapdragon-805-25ghz-128bit-memory-interface-d3d11class-graphics-more
> > 
> > I'm pretty sure idiv support came earlier, but I don't have the
> > specifics on hand.
> 
> I have seen that article, but didn't trust it as a canonical
> source of information here.
> 
> If you can confirm that it's right, that would mean that we
> don't support LPAE on mach-qcom, as the only SoC with Krait 450
> seems to be APQ8084, and mainline Linux doesn't run on that.

arch/arm/boot/dts/qcom-apq8084.dtsi exists in the mainline
kernel. We support more than what's in the Kconfig language
under mach-qcom. And yes LPAE is supported by apq8084 (as is
IDIV). Here's the /proc/cpuinfo on that device.

# cat /proc/cpuinfo
processor       : 0
model name      : ARMv7 Processor rev 1 (v7l)
BogoMIPS        : 38.40
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x51
CPU architecture: 7
CPU variant     : 0x3
CPU part        : 0x06f
CPU revision    : 1

processor       : 1
model name      : ARMv7 Processor rev 1 (v7l)
BogoMIPS        : 38.40
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x51
CPU architecture: 7
CPU variant     : 0x3
CPU part        : 0x06f
CPU revision    : 1

processor       : 2
model name      : ARMv7 Processor rev 1 (v7l)
BogoMIPS        : 38.40
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x51
CPU architecture: 7
CPU variant     : 0x3
CPU part        : 0x06f
CPU revision    : 1

processor       : 3
model name      : ARMv7 Processor rev 1 (v7l)
BogoMIPS        : 38.40
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x51
CPU architecture: 7
CPU variant     : 0x3
CPU part        : 0x06f
CPU revision    : 1

Hardware        : Qualcomm (Flattened Device Tree)
Revision        : 0000
Serial          : 0000000000000000

> 
> The ones we do support are MSM8x60 (Scorpion), MSM8960
> (Krait-without-number),and MSM7874 (Krait 400). Do those all
> support IDIV but not LPAE?
> 

Krait supports IDIV for all versions. Scorpion doesn't support
IDIV or lpae. Here's the output of /proc/cpuinfo on that device. 

# cat /proc/cpuinfo
processor       : 0
model name      : ARMv7 Processor rev 2 (v7l)
BogoMIPS        : 13.50
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpd32
CPU implementer : 0x51
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0x02d
CPU revision    : 2

processor       : 1
model name      : ARMv7 Processor rev 2 (v7l)
BogoMIPS        : 13.50
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpd32
CPU implementer : 0x51
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0x02d
CPU revision    : 2

Hardware        : Qualcomm (Flattened Device Tree)
Revision        : 0000
Serial          : 0000000000000000

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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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