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Groups > linux.kernel > #1276502
| 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 | 2015-11-24 15:10 +0100 |
| Message-ID | <qyms9-FQ-1@gated-at.bofh.it> (permalink) |
| References | (4 earlier) <qyjkB-6ZF-5@gated-at.bofh.it> <qykJI-7YL-25@gated-at.bofh.it> <qykTn-82V-9@gated-at.bofh.it> <qykTn-82V-7@gated-at.bofh.it> <qyms9-FQ-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Russell King - ARM Linux <linux@arm.linux.org.uk> writes: > On Tue, Nov 24, 2015 at 12:29:06PM +0000, Måns Rullgård wrote: >> Russell King - ARM Linux <linux@arm.linux.org.uk> writes: >> >> > On Tue, Nov 24, 2015 at 12:10:02PM +0000, Måns Rullgård wrote: >> >> Russell King - ARM Linux <linux@arm.linux.org.uk> writes: >> >> >> >> > On Tue, Nov 24, 2015 at 11:38:53AM +0100, Arnd Bergmann wrote: >> >> >> I suggested using -mcpu=cortex-a15 because there are old gcc versions >> >> >> that don't know about -march=armv7ve or -march=armv7-a+idiv yet, but >> >> >> that do understand -mcpu=cortex-a15. >> >> > >> >> > That's not all. The bigger problem is that there are toolchains out >> >> > there which accept these options, but do _not_ support IDIV in either >> >> > ARM or Thumb mode. I'm afraid that makes it impossible to add this >> >> > feature to the mainline kernel in this form: we need to run a test >> >> > build to check that -march=armv7ve or what-not really does work >> >> > through both GCC and GAS. >> >> >> >> If the compiler accepts the option but doesn't actually emit any div >> >> instructions, is there any real harm? >> > >> > That's not what I've found. I've found that asking the assembler >> > to accept idiv instructions appears to be ignored, which is something >> > completely different. >> > >> > Further to this, what it comes down to is the stupid idea that the >> > compiler should embed .arch / .cpu in the assembly output, which has >> > the effect of overriding the command line arguments given to it via >> > -Wa. So, giving -Wa,-mcpu=cortex-a15 is a total no-op, because the >> > first thing in the assembly output is: >> > >> > .arch armv7-a >> > >> > which kills off any attempt to set the assembly level ISA from the >> > command line. >> >> Oh, you mean the compiler knows about the instructions but the assembler >> doesn't or isn't passed the right options. It's infuriating when that >> happens. > > No, that isn't what I meant. Then what do you mean? The compiler either emits the instructions or it doesn't. If it doesn't, what the assembler accepts is irrelevant. -- Måns Rullgård mans@mansr.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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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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