On 06/24/2014 04:03 PM, Maciej W. Rozycki wrote: > On Thu, 3 Apr 2014, Theodore Ts'o wrote: > >> fs/mbcache.c: doucple the locking of local from global data > > This change causes breakage: > > fs/built-in.o: In function `__mb_cache_entry_release': > mbcache.c:(.text+0x56b3c): undefined reference to `log2' > mbcache.c:(.text+0x56b3c): relocation truncated to fit: R_MIPS_26 against `log2' > mbcache.c:(.text+0x56b74): undefined reference to `__fixunsdfsi' > mbcache.c:(.text+0x56b74): relocation truncated to fit: R_MIPS_26 against `__fixunsdfsi' > mbcache.c:(.text+0x56be4): undefined reference to `log2' > mbcache.c:(.text+0x56be4): relocation truncated to fit: R_MIPS_26 against `log2' > mbcache.c:(.text+0x56bf0): undefined reference to `__fixunsdfsi' > mbcache.c:(.text+0x56bf0): relocation truncated to fit: R_MIPS_26 against `__fixunsdfsi' > > and so on, and so on. It uses __builtin_log2() that is a floating-point > function, its corresponding <math.h> prototype is: > > -- Function: double log2 (double X) > > (GCC builtins are of course implicitly prototyped). Please note that > floating-point calculations are not allowed in the kernel and relying on > the compiler to optimise them away is risky to say the least. > > Can you please rewrite the fragment using __builtin_log2() so as to avoid > the floating-point calculation, using ffs() or suchlike perhaps? > > Maciej > Sorry and thanks for notifying me about the problem. I've submitted the fix, using ilog2, and could be found at, https://lkml.org/lkml/2014/5/30/462 Please let me know if you have any comment. Thanks, Mak. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
