* [PATCH v4] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends
@ 2012-08-31 15:02 Guenter Roeck
2012-08-31 19:38 ` Andrew Morton
2012-09-09 14:57 ` Geert Uytterhoeven
0 siblings, 2 replies; 9+ messages in thread
From: Guenter Roeck @ 2012-08-31 15:02 UTC (permalink / raw)
To: linux-kernel
Cc: Andrew Morton, Pekka Enberg, Ingo Molnar, H. Peter Anvin,
Jean Delvare, lm-sensors, Guenter Roeck
DIV_ROUND_CLOSEST returns a bad result for negative dividends:
DIV_ROUND_CLOSEST(-2, 2) = 0
Most of the time this does not matter. However, in the hardware monitoring
subsystem, DIV_ROUND_CLOSEST is sometimes used on integers which can be
negative (such as temperatures).
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v4: Don't address negative divisors to improve chances for compile-time
optimization. Document DIV_ROUND_CLOSEST macro.
v3: Instead of adding a new macro, fix DIV_ROUND_CLOSEST.
This version works for negative dividend and divisor.
v2: v1 did not work if typeof(divisor) was an unsigned variable type
(which can obviously not be negative).
Rework to revert to DIV_ROUND_CLOSEST if the dividend is unsigned,
or if it is signed but non-negative.
include/linux/kernel.h | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 6043821..594b419 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -82,10 +82,18 @@
__x - (__x % (y)); \
} \
)
+
+/*
+ * Divide positive or negative dividend by positive divisor and round
+ * to closest integer. Result is undefined for negative divisors.
+ */
#define DIV_ROUND_CLOSEST(x, divisor)( \
{ \
- typeof(divisor) __divisor = divisor; \
- (((x) + ((__divisor) / 2)) / (__divisor)); \
+ typeof(x) __x = x; \
+ typeof(divisor) __d = divisor; \
+ (((typeof(x))-1) >= 0 || (__x) >= 0) ? \
+ (((__x) + ((__d) / 2)) / (__d)) : \
+ (((__x) - ((__d) / 2)) / (__d)); \
} \
)
--
1.7.9.7
^ permalink raw reply related [flat|nested] 9+ messages in thread* Re: [PATCH v4] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends 2012-08-31 15:02 [PATCH v4] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends Guenter Roeck @ 2012-08-31 19:38 ` Andrew Morton 2012-08-31 21:05 ` Guenter Roeck 2012-09-01 17:02 ` Jean Delvare 2012-09-09 14:57 ` Geert Uytterhoeven 1 sibling, 2 replies; 9+ messages in thread From: Andrew Morton @ 2012-08-31 19:38 UTC (permalink / raw) To: Guenter Roeck Cc: linux-kernel, Pekka Enberg, Ingo Molnar, H. Peter Anvin, Jean Delvare, lm-sensors On Fri, 31 Aug 2012 08:02:19 -0700 Guenter Roeck <linux@roeck-us.net> wrote: > DIV_ROUND_CLOSEST returns a bad result for negative dividends: > DIV_ROUND_CLOSEST(-2, 2) = 0 > > Most of the time this does not matter. However, in the hardware monitoring > subsystem, DIV_ROUND_CLOSEST is sometimes used on integers which can be > negative (such as temperatures). > > ... > > + > +/* > + * Divide positive or negative dividend by positive divisor and round > + * to closest integer. Result is undefined for negative divisors. > + */ > #define DIV_ROUND_CLOSEST(x, divisor)( \ > { \ > - typeof(divisor) __divisor = divisor; \ > - (((x) + ((__divisor) / 2)) / (__divisor)); \ > + typeof(x) __x = x; \ > + typeof(divisor) __d = divisor; \ > + (((typeof(x))-1) >= 0 || (__x) >= 0) ? \ > + (((__x) + ((__d) / 2)) / (__d)) : \ > + (((__x) - ((__d) / 2)) / (__d)); \ > } \ Looks good to me. The patch causes no change in text size for kernel/sched/fair.o and drivers/cpuidle/governors/menu.o, so it seems that the cc trickery is working. I'll add it to my tree for testing - please merge this via your tree. ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends 2012-08-31 19:38 ` Andrew Morton @ 2012-08-31 21:05 ` Guenter Roeck 2012-09-01 17:02 ` Jean Delvare 1 sibling, 0 replies; 9+ messages in thread From: Guenter Roeck @ 2012-08-31 21:05 UTC (permalink / raw) To: Andrew Morton Cc: linux-kernel, Pekka Enberg, Ingo Molnar, H. Peter Anvin, Jean Delvare, lm-sensors On Fri, Aug 31, 2012 at 12:38:12PM -0700, Andrew Morton wrote: > On Fri, 31 Aug 2012 08:02:19 -0700 > Guenter Roeck <linux@roeck-us.net> wrote: > > > DIV_ROUND_CLOSEST returns a bad result for negative dividends: > > DIV_ROUND_CLOSEST(-2, 2) = 0 > > > > Most of the time this does not matter. However, in the hardware monitoring > > subsystem, DIV_ROUND_CLOSEST is sometimes used on integers which can be > > negative (such as temperatures). > > > > ... > > > > + > > +/* > > + * Divide positive or negative dividend by positive divisor and round > > + * to closest integer. Result is undefined for negative divisors. > > + */ > > #define DIV_ROUND_CLOSEST(x, divisor)( \ > > { \ > > - typeof(divisor) __divisor = divisor; \ > > - (((x) + ((__divisor) / 2)) / (__divisor)); \ > > + typeof(x) __x = x; \ > > + typeof(divisor) __d = divisor; \ > > + (((typeof(x))-1) >= 0 || (__x) >= 0) ? \ > > + (((__x) + ((__d) / 2)) / (__d)) : \ > > + (((__x) - ((__d) / 2)) / (__d)); \ > > } \ > > Looks good to me. The patch causes no change in text size for > kernel/sched/fair.o and drivers/cpuidle/governors/menu.o, so it seems > that the cc trickery is working. > > I'll add it to my tree for testing - please merge this via your tree. > Will do. Thanks, Guenter ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends 2012-08-31 19:38 ` Andrew Morton 2012-08-31 21:05 ` Guenter Roeck @ 2012-09-01 17:02 ` Jean Delvare 2012-09-02 2:14 ` Guenter Roeck 1 sibling, 1 reply; 9+ messages in thread From: Jean Delvare @ 2012-09-01 17:02 UTC (permalink / raw) To: Andrew Morton Cc: Guenter Roeck, linux-kernel, Pekka Enberg, Ingo Molnar, H. Peter Anvin, lm-sensors Hi Andrew, Guenter, On Fri, 31 Aug 2012 12:38:12 -0700, Andrew Morton wrote: > On Fri, 31 Aug 2012 08:02:19 -0700 > Guenter Roeck <linux@roeck-us.net> wrote: > > > DIV_ROUND_CLOSEST returns a bad result for negative dividends: > > DIV_ROUND_CLOSEST(-2, 2) = 0 > > > > Most of the time this does not matter. However, in the hardware monitoring > > subsystem, DIV_ROUND_CLOSEST is sometimes used on integers which can be > > negative (such as temperatures). > > > > ... > > > > + > > +/* > > + * Divide positive or negative dividend by positive divisor and round > > + * to closest integer. Result is undefined for negative divisors. > > + */ > > #define DIV_ROUND_CLOSEST(x, divisor)( \ > > { \ > > - typeof(divisor) __divisor = divisor; \ > > - (((x) + ((__divisor) / 2)) / (__divisor)); \ > > + typeof(x) __x = x; \ > > + typeof(divisor) __d = divisor; \ > > + (((typeof(x))-1) >= 0 || (__x) >= 0) ? \ > > + (((__x) + ((__d) / 2)) / (__d)) : \ > > + (((__x) - ((__d) / 2)) / (__d)); \ > > } \ > > Looks good to me. My testing looks good too. Acked-by: Jean Delvare <khali@linux-fr.org> > The patch causes no change in text size for > kernel/sched/fair.o and drivers/cpuidle/governors/menu.o, so it seems > that the cc trickery is working. Indeed. I looked for test size increase, and for my config, besides hwmon, I only spotted the following ones: drivers/media/rc/mceusb.o drivers/gpu/drm/i915/intel_pm.o drivers/tty/serial/pch_uart.o These don't look like hot paths, so I'd say we don't care. Plus the intel_pm one can probably be solved by using an unsigned int, I don't see why/how ia_freq could be negative (negative frequency anyone?) And for mceusb it can be solved easily by changing "1" to "1U". For hwmon drivers, we typically only use DIV_ROUND_CLOSEST when the user changes a setting, this isn't a frequent event. Plus, this is exactly the case we are fixing here, as temperature limits, and to a lesser extent voltage limits, can be negative. > I'll add it to my tree for testing - please merge this via your tree. -- Jean Delvare ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends 2012-09-01 17:02 ` Jean Delvare @ 2012-09-02 2:14 ` Guenter Roeck 0 siblings, 0 replies; 9+ messages in thread From: Guenter Roeck @ 2012-09-02 2:14 UTC (permalink / raw) To: Jean Delvare Cc: Andrew Morton, linux-kernel, Pekka Enberg, Ingo Molnar, H. Peter Anvin, lm-sensors On Sat, Sep 01, 2012 at 07:02:54PM +0200, Jean Delvare wrote: > Hi Andrew, Guenter, > > On Fri, 31 Aug 2012 12:38:12 -0700, Andrew Morton wrote: > > On Fri, 31 Aug 2012 08:02:19 -0700 > > Guenter Roeck <linux@roeck-us.net> wrote: > > > > > DIV_ROUND_CLOSEST returns a bad result for negative dividends: > > > DIV_ROUND_CLOSEST(-2, 2) = 0 > > > > > > Most of the time this does not matter. However, in the hardware monitoring > > > subsystem, DIV_ROUND_CLOSEST is sometimes used on integers which can be > > > negative (such as temperatures). > > > > > > ... > > > > > > + > > > +/* > > > + * Divide positive or negative dividend by positive divisor and round > > > + * to closest integer. Result is undefined for negative divisors. > > > + */ > > > #define DIV_ROUND_CLOSEST(x, divisor)( \ > > > { \ > > > - typeof(divisor) __divisor = divisor; \ > > > - (((x) + ((__divisor) / 2)) / (__divisor)); \ > > > + typeof(x) __x = x; \ > > > + typeof(divisor) __d = divisor; \ > > > + (((typeof(x))-1) >= 0 || (__x) >= 0) ? \ > > > + (((__x) + ((__d) / 2)) / (__d)) : \ > > > + (((__x) - ((__d) / 2)) / (__d)); \ > > > } \ > > > > Looks good to me. > > My testing looks good too. > > Acked-by: Jean Delvare <khali@linux-fr.org> > Thanks a lot! > > The patch causes no change in text size for > > kernel/sched/fair.o and drivers/cpuidle/governors/menu.o, so it seems > > that the cc trickery is working. > > Indeed. I looked for test size increase, and for my config, besides > hwmon, I only spotted the following ones: > > drivers/media/rc/mceusb.o > drivers/gpu/drm/i915/intel_pm.o > drivers/tty/serial/pch_uart.o > > These don't look like hot paths, so I'd say we don't care. Plus the > intel_pm one can probably be solved by using an unsigned int, I don't > see why/how ia_freq could be negative (negative frequency anyone?) And > for mceusb it can be solved easily by changing "1" to "1U". > Yes, it helps a lot that the C trickery optimizes the changes away most of the time. I'll let the patch rest in -next for a few more days before I send it to Linus. Guenter ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends 2012-08-31 15:02 [PATCH v4] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends Guenter Roeck 2012-08-31 19:38 ` Andrew Morton @ 2012-09-09 14:57 ` Geert Uytterhoeven 2012-09-09 16:17 ` Guenter Roeck 1 sibling, 1 reply; 9+ messages in thread From: Geert Uytterhoeven @ 2012-09-09 14:57 UTC (permalink / raw) To: Guenter Roeck Cc: linux-kernel, Andrew Morton, Pekka Enberg, Ingo Molnar, H. Peter Anvin, Jean Delvare, lm-sensors On Fri, Aug 31, 2012 at 5:02 PM, Guenter Roeck <linux@roeck-us.net> wrote: > DIV_ROUND_CLOSEST returns a bad result for negative dividends: > DIV_ROUND_CLOSEST(-2, 2) = 0 > > Most of the time this does not matter. However, in the hardware monitoring > subsystem, DIV_ROUND_CLOSEST is sometimes used on integers which can be > negative (such as temperatures). This seems to cause 3 new warnings in my m68k builds of v3.6-rc5: drivers/hwmon/mcp3021.c:76: warning: comparison is always true due to limited range of data type drivers/ide/ide-cd.c:1158: warning: comparison is always true due to limited range of data type drivers/ide/ide-cd.c:1159: warning: comparison is always true due to limited range of data type $ m68k-linux-gnu-gcc -v Using built-in specs. Target: m68k-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++ --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/m68k-linux-gnu/include/c++/4.1.2 --program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu --enable-libstdcxx-debug --disable-libssp --disable-werror --enable-checking=release --program-prefix=m68k-linux-gnu- --includedir=/usr/m68k-linux-gnu/include --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=m68k-linux-gnu Thread model: posix gcc version 4.1.2 20061115 (prerelease) (Ubuntu 4.1.1-21) Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends 2012-09-09 14:57 ` Geert Uytterhoeven @ 2012-09-09 16:17 ` Guenter Roeck 2012-09-09 20:38 ` Geert Uytterhoeven 0 siblings, 1 reply; 9+ messages in thread From: Guenter Roeck @ 2012-09-09 16:17 UTC (permalink / raw) To: Geert Uytterhoeven Cc: linux-kernel, Andrew Morton, Pekka Enberg, Ingo Molnar, H. Peter Anvin, Jean Delvare, lm-sensors On Sun, Sep 09, 2012 at 04:57:34PM +0200, Geert Uytterhoeven wrote: > On Fri, Aug 31, 2012 at 5:02 PM, Guenter Roeck <linux@roeck-us.net> wrote: > > DIV_ROUND_CLOSEST returns a bad result for negative dividends: > > DIV_ROUND_CLOSEST(-2, 2) = 0 > > > > Most of the time this does not matter. However, in the hardware monitoring > > subsystem, DIV_ROUND_CLOSEST is sometimes used on integers which can be > > negative (such as temperatures). > > This seems to cause 3 new warnings in my m68k builds of v3.6-rc5: > > drivers/hwmon/mcp3021.c:76: warning: comparison is always true due to > limited range of data type > drivers/ide/ide-cd.c:1158: warning: comparison is always true due to > limited range of data type > drivers/ide/ide-cd.c:1159: warning: comparison is always true due to > limited range of data type > > $ m68k-linux-gnu-gcc -v > Using built-in specs. > Target: m68k-linux-gnu > Configured with: ../src/configure -v --enable-languages=c,c++ > --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib > --without-included-gettext --enable-threads=posix --enable-nls > --with-gxx-include-dir=/usr/m68k-linux-gnu/include/c++/4.1.2 > --program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu > --enable-libstdcxx-debug --disable-libssp --disable-werror > --enable-checking=release --program-prefix=m68k-linux-gnu- > --includedir=/usr/m68k-linux-gnu/include --build=x86_64-linux-gnu > --host=x86_64-linux-gnu --target=m68k-linux-gnu > Thread model: posix > gcc version 4.1.2 20061115 (prerelease) (Ubuntu 4.1.1-21) > Hi Gert, The "always true" condition is on purpose to cause the compiler to optimize the expression away. I don't see the warnings myself, on none of the targets I am building (x86, ppc, arm, mips), but then I am using much more recent compiler versions. Odd is that you only see the warnings on "u16" and not elsewhere. I don't immediately see the warnings with a more recent m68k compiler (4.6.3), nor with any other target (x86, ppc, arm, mips) in my nightly builds. Can you send me your configuration ? Also, do you know where I can find the Ubuntu/Debian package for your compiler version, by any chance ? Thanks, Guenter ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends 2012-09-09 16:17 ` Guenter Roeck @ 2012-09-09 20:38 ` Geert Uytterhoeven 2012-09-09 21:30 ` Guenter Roeck 0 siblings, 1 reply; 9+ messages in thread From: Geert Uytterhoeven @ 2012-09-09 20:38 UTC (permalink / raw) To: Guenter Roeck Cc: linux-kernel, Andrew Morton, Pekka Enberg, Ingo Molnar, H. Peter Anvin, Jean Delvare, lm-sensors Hi Günter, On Sun, Sep 9, 2012 at 6:17 PM, Guenter Roeck <linux@roeck-us.net> wrote: > On Sun, Sep 09, 2012 at 04:57:34PM +0200, Geert Uytterhoeven wrote: >> On Fri, Aug 31, 2012 at 5:02 PM, Guenter Roeck <linux@roeck-us.net> wrote: >> > DIV_ROUND_CLOSEST returns a bad result for negative dividends: >> > DIV_ROUND_CLOSEST(-2, 2) = 0 >> > >> > Most of the time this does not matter. However, in the hardware monitoring >> > subsystem, DIV_ROUND_CLOSEST is sometimes used on integers which can be >> > negative (such as temperatures). >> >> This seems to cause 3 new warnings in my m68k builds of v3.6-rc5: >> >> drivers/hwmon/mcp3021.c:76: warning: comparison is always true due to >> limited range of data type >> drivers/ide/ide-cd.c:1158: warning: comparison is always true due to >> limited range of data type >> drivers/ide/ide-cd.c:1159: warning: comparison is always true due to >> limited range of data type >> >> $ m68k-linux-gnu-gcc -v >> Using built-in specs. >> Target: m68k-linux-gnu >> Configured with: ../src/configure -v --enable-languages=c,c++ >> --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib >> --without-included-gettext --enable-threads=posix --enable-nls >> --with-gxx-include-dir=/usr/m68k-linux-gnu/include/c++/4.1.2 >> --program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu >> --enable-libstdcxx-debug --disable-libssp --disable-werror >> --enable-checking=release --program-prefix=m68k-linux-gnu- >> --includedir=/usr/m68k-linux-gnu/include --build=x86_64-linux-gnu >> --host=x86_64-linux-gnu --target=m68k-linux-gnu >> Thread model: posix >> gcc version 4.1.2 20061115 (prerelease) (Ubuntu 4.1.1-21) >> > The "always true" condition is on purpose to cause the compiler to optimize the > expression away. I don't see the warnings myself, on none of the targets I am > building (x86, ppc, arm, mips), but then I am using much more recent compiler > versions. Odd is that you only see the warnings on "u16" and not elsewhere. > > I don't immediately see the warnings with a more recent m68k compiler (4.6.3), > nor with any other target (x86, ppc, arm, mips) in my nightly builds. I also don't see it in any of the linux-next builds of v3.6-rc5. So probably it's just a gcc 4.1.2 issue... > Can you send me your configuration ? The ide-cd one shows up in any config that enables ide-cd, incl. defconfig and allmodconfig. The mcp3021 one I only see in allmodconfig. > Also, do you know where I can find the Ubuntu/Debian package for your compiler > version, by any chance ? It's not from an official binary package. I built the cross-compiler from the then current gcc 4.1.1-21 sources in Ubuntu. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends 2012-09-09 20:38 ` Geert Uytterhoeven @ 2012-09-09 21:30 ` Guenter Roeck 0 siblings, 0 replies; 9+ messages in thread From: Guenter Roeck @ 2012-09-09 21:30 UTC (permalink / raw) To: Geert Uytterhoeven Cc: linux-kernel, Andrew Morton, Pekka Enberg, Ingo Molnar, H. Peter Anvin, Jean Delvare, lm-sensors On Sun, Sep 09, 2012 at 10:38:41PM +0200, Geert Uytterhoeven wrote: > Hi Günter, > > On Sun, Sep 9, 2012 at 6:17 PM, Guenter Roeck <linux@roeck-us.net> wrote: > > On Sun, Sep 09, 2012 at 04:57:34PM +0200, Geert Uytterhoeven wrote: > >> On Fri, Aug 31, 2012 at 5:02 PM, Guenter Roeck <linux@roeck-us.net> wrote: > >> > DIV_ROUND_CLOSEST returns a bad result for negative dividends: > >> > DIV_ROUND_CLOSEST(-2, 2) = 0 > >> > > >> > Most of the time this does not matter. However, in the hardware monitoring > >> > subsystem, DIV_ROUND_CLOSEST is sometimes used on integers which can be > >> > negative (such as temperatures). > >> > >> This seems to cause 3 new warnings in my m68k builds of v3.6-rc5: > >> > >> drivers/hwmon/mcp3021.c:76: warning: comparison is always true due to > >> limited range of data type > >> drivers/ide/ide-cd.c:1158: warning: comparison is always true due to > >> limited range of data type > >> drivers/ide/ide-cd.c:1159: warning: comparison is always true due to > >> limited range of data type > >> > >> $ m68k-linux-gnu-gcc -v > >> Using built-in specs. > >> Target: m68k-linux-gnu > >> Configured with: ../src/configure -v --enable-languages=c,c++ > >> --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib > >> --without-included-gettext --enable-threads=posix --enable-nls > >> --with-gxx-include-dir=/usr/m68k-linux-gnu/include/c++/4.1.2 > >> --program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu > >> --enable-libstdcxx-debug --disable-libssp --disable-werror > >> --enable-checking=release --program-prefix=m68k-linux-gnu- > >> --includedir=/usr/m68k-linux-gnu/include --build=x86_64-linux-gnu > >> --host=x86_64-linux-gnu --target=m68k-linux-gnu > >> Thread model: posix > >> gcc version 4.1.2 20061115 (prerelease) (Ubuntu 4.1.1-21) > >> > > The "always true" condition is on purpose to cause the compiler to optimize the > > expression away. I don't see the warnings myself, on none of the targets I am > > building (x86, ppc, arm, mips), but then I am using much more recent compiler > > versions. Odd is that you only see the warnings on "u16" and not elsewhere. > > > > I don't immediately see the warnings with a more recent m68k compiler (4.6.3), > > nor with any other target (x86, ppc, arm, mips) in my nightly builds. > > I also don't see it in any of the linux-next builds of v3.6-rc5. So > probably it's just > a gcc 4.1.2 issue... > > > Can you send me your configuration ? > > The ide-cd one shows up in any config that enables ide-cd, incl. defconfig and > allmodconfig. > The mcp3021 one I only see in allmodconfig. > I tried both and did not see the problem. I agree, it does look like a compiler version problem. > > Also, do you know where I can find the Ubuntu/Debian package for your compiler > > version, by any chance ? > > It's not from an official binary package. I built the cross-compiler > from the then > current gcc 4.1.1-21 sources in Ubuntu. > Ok. Just in case you are interested, I installed the m68k cross-compiler from deb http://www.freewrt.org/~tg/debs68k/ cross main For my other targets, I use Yocto builds. I think I'll let this go as false positive for now, unless there are problems with more recent compilers. Thanks, Guenter ^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2012-09-09 21:30 UTC | newest] Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2012-08-31 15:02 [PATCH v4] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends Guenter Roeck 2012-08-31 19:38 ` Andrew Morton 2012-08-31 21:05 ` Guenter Roeck 2012-09-01 17:02 ` Jean Delvare 2012-09-02 2:14 ` Guenter Roeck 2012-09-09 14:57 ` Geert Uytterhoeven 2012-09-09 16:17 ` Guenter Roeck 2012-09-09 20:38 ` Geert Uytterhoeven 2012-09-09 21:30 ` Guenter Roeck
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).