Messages in this thread | | | Date | Thu, 12 Aug 2010 15:41:33 -0500 | From | Larry Finger <> | Subject | Re: Problem with commit deda2e81961e96be4f2c09328baca4710a2fd1a0 |
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On 08/12/2010 03:26 PM, Linus Torvalds wrote: > On Thu, Aug 12, 2010 at 1:18 PM, Larry Finger <Larry.Finger@lwfinger.net> wrote: >> >> With the above commit, building an i386 version of the kernel results in the >> following from the build: >> >> kernel/built-in.o: In function `logarithmic_accumulation': >> /home/finger/linux-realtek/kernel/time/timekeeping.c:715: undefined reference to >> `__umoddi3' >> /home/finger/linux-realtek/kernel/time/timekeeping.c:715: undefined reference to >> `__udivdi3' >> make: *** [.tmp_vmlinux1] Error 1 >> >> Reverting the patch allows the system to build correctly. > > Damn. It's your compiler turning a while-loop into a divide. Which > likely isn't even an optimization, but whatever. > > John: I think that while-loop needs to be something like > > if (raw_nsecs >= NSEC_PER_SEC) { > u64 raw_secs = raw_nsecs; > raw_nsecs = do_div(raw_secs, NSEC_PER_SEC); > raw_time.tv_sec += taw_secs; > } > raw_time.tc_nsec = raw_nsecs; > > which is sad and overly complicated, but the simple thing seems to get > messed up by the compiler. > > Untested. Maybe I got the complex do_div() semantics wrong. Somebody > needs to check.
I'll try it. The system with the problem has gcc (SUSE Linux) 4.3.2 [gcc-4_3-branch revision 141291]. That is on a 64-bit system cross compiling with ARCH=i386.
The real 32-bit system with gcc (SUSE Linux) 4.5.0 20100604 [gcc-4_5-branch revision 160292] builds OK. It just wasn't finished when I wrote the first message.
Larry
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