Re: [PATCH v2 1/2] scripts: Add a recorduidiv program

From	Michal Marek <mmarek@suse.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 1/2] scripts: Add a recorduidiv program
Date	2015-11-30 16:20 +0100
Message-ID	<qAype-5id-67@gated-at.bofh.it> (permalink)
References	<qyQgy-3rg-7@gated-at.bofh.it> <qyQgy-3rg-15@gated-at.bofh.it> <qyRZ0-4Aw-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 2015-11-26 00:47, Russell King - ARM Linux wrote:
> On Wed, Nov 25, 2015 at 01:51:03PM -0800, Stephen Boyd wrote:
>> The ARM compiler inserts calls to __aeabi_uidiv() and
>> __aeabi_idiv() when it needs to perform division on signed and
>> unsigned integers. If a processor has support for the udiv and
>> sdiv division instructions the calls to these support routines
>> can be replaced with those instructions. Therefore, record the
>> location of calls to these library functions into two sections
>> (one for udiv and one for sdiv) similar to how we trace calls to
>> mcount. When the kernel boots up it will check to see if the
>> processor supports the instructions and then patch the call sites
>> with the instruction.
> 
> Do we have any resolution on these programs which modify the object
> files in-place, rather than breaking any hard-links which may be
> present (eg, as a result of using ccache in hard-link mode) ?

Good point, but I do not think anybody is using CCACHE_HARDLINK with the
kernel. As the manpage says, it is going to confuse make, so the time
saved by ccache would be offset by make trying to recompile all *.c
files each time.

Michal

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Thread

[PATCH v2 0/2] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-25 23:00 +0100
  [PATCH v2 1/2] scripts: Add a recorduidiv program Stephen Boyd <sboyd@codeaurora.org> - 2015-11-25 23:00 +0100
    Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-26 00:50 +0100
      Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Michal Marek <mmarek@suse.com> - 2015-11-30 16:20 +0100
        Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-30 16:40 +0100
          Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Michal Marek <mmarek@suse.com> - 2015-11-30 16:50 +0100
            Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Michal Marek <mmarek@suse.cz> - 2015-12-01 17:10 +0100
              Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-12-01 17:30 +0100
                Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Michal Marek <mmarek@suse.cz> - 2015-12-01 17:50 +0100
                Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Steven Rostedt <rostedt@goodmis.org> - 2015-12-01 17:50 +0100
                Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-12-01 18:20 +0100
                Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Steven Rostedt <rostedt@goodmis.org> - 2015-12-01 18:30 +0100
                Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-12-01 19:20 +0100
                Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Michal Marek <mmarek@suse.cz> - 2015-12-01 22:40 +0100
                Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-12-02 11:30 +0100
                Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Steven Rostedt <rostedt@goodmis.org> - 2015-12-02 15:10 +0100
                Re: [PATCH] scripts: recordmcount: break hardlinks Steven Rostedt <rostedt@goodmis.org> - 2015-12-11 15:40 +0100
                Re: [PATCH] scripts: recordmcount: break hardlinks Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-12-11 15:50 +0100
                Re: [PATCH] scripts: recordmcount: break hardlinks Steven Rostedt <rostedt@goodmis.org> - 2015-12-11 16:10 +0100
                Re: [PATCH] scripts: recordmcount: break hardlinks Steven Rostedt <rostedt@goodmis.org> - 2015-12-11 19:20 +0100
                Re: [PATCH] scripts: recordmcount: break hardlinks Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-12-11 19:40 +0100
                Re: [PATCH] scripts: recordmcount: break hardlinks Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-12-11 20:00 +0100
                Re: [PATCH] scripts: recordmcount: break hardlinks Steven Rostedt <rostedt@goodmis.org> - 2015-12-11 20:30 +0100
                Re: [PATCH] scripts: recordmcount: break hardlinks Steven Rostedt <rostedt@goodmis.org> - 2015-12-11 20:00 +0100
  [PATCH v2 2/2] ARM: Replace calls to __aeabi_{u}idiv with udiv/sdiv instructions Stephen Boyd <sboyd@codeaurora.org> - 2015-11-25 23:00 +0100
    Re: [PATCH v2 2/2] ARM: Replace calls to __aeabi_{u}idiv with  udiv/sdiv instructions Nicolas Pitre <nico@fluxnic.net> - 2015-11-26 00:30 +0100
      Re: [PATCH v2 2/2] ARM: Replace calls to __aeabi_{u}idiv with  udiv/sdiv instructions Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-26 01:10 +0100
      Re: [PATCH v2 2/2] ARM: Replace calls to __aeabi_{u}idiv with udiv/sdiv instructions Måns Rullgård <mans@mansr.com> - 2015-11-26 01:10 +0100
        Re: [PATCH v2 2/2] ARM: Replace calls to __aeabi_{u}idiv with  udiv/sdiv instructions Nicolas Pitre <nico@fluxnic.net> - 2015-11-26 01:50 +0100
          Re: [PATCH v2 2/2] ARM: Replace calls to __aeabi_{u}idiv with udiv/sdiv instructions Måns Rullgård <mans@mansr.com> - 2015-11-26 02:00 +0100
            Re: [PATCH v2 2/2] ARM: Replace calls to __aeabi_{u}idiv with  udiv/sdiv instructions Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-26 02:30 +0100
              Re: [PATCH v2 2/2] ARM: Replace calls to __aeabi_{u}idiv with udiv/sdiv instructions Måns Rullgård <mans@mansr.com> - 2015-11-26 03:30 +0100
                Re: [PATCH v2 2/2] ARM: Replace calls to __aeabi_{u}idiv with  udiv/sdiv instructions Nicolas Pitre <nico@fluxnic.net> - 2015-11-26 06:40 +0100
                Re: [PATCH v2 2/2] ARM: Replace calls to __aeabi_{u}idiv with udiv/sdiv instructions Måns Rullgård <mans@mansr.com> - 2015-11-26 13:50 +0100
    Re: [PATCH v2 2/2] ARM: Replace calls to __aeabi_{u}idiv with  udiv/sdiv instructions Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-11-26 01:10 +0100

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