On Tue, 24 Jun 2014, Thavatchai Makphaibulchoke wrote: > > 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, that's even better, and the kernel builds and boots. I saw no trace of your proposal going anywhere so I gave it my `Reviewed-by' tag in case that helps. Maciej -- 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
