On Fri, Mar 01, 2019 at 04:10:12PM +0100, Geert Uytterhoeven wrote: > Hi Günter, > > (this time without the bogus "h" ;-) > > On Fri, Mar 1, 2019 at 3:33 PM Guenter Roeck <[email protected]> wrote: > > On 3/1/19 12:04 AM, Geert Uytterhoeven wrote: > > > On Thu, Feb 28, 2019 at 9:52 PM Guenter Roeck <[email protected]> wrote: > > >> when trying to build m68k:defconfig with gcc-8.3.0 (built using > > >> buildall), > > >> I get the following error. > > >> > > >> m68k-linux-ld: drivers/rtc/rtc-proc.o: in function > > >> `is_rtc_hctosys.isra.0': > > >> rtc-proc.c:(.text+0x2a0): undefined reference to `strcmp' > > >> > > >> rtc-proc.c doesn't actually call strcmp(); it calls strncmp(), > > >> but it looks like the compiler optimizes it away. > > >> > > >> The same problem is also seen in a few other places when trying to build > > >> m68k:allmodconfig. In each instance, the compiler replaces strncmp() with > > >> strcmp(). I don't see the build failure with any other target, even > > >> though > > >> the same optimization happens there as well. > > >> > > >> Do you have an idea what is going on, and what I might have to do to fix > > >> the problem (presumably in the toolchain) ? > > > > > > A fix for this is queued in my for-v5.1 branch: > > > https://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k.git/commit/?h=for-v5.1&id=28713169d879b67be2ef2f84dcf54905de238294 > > > ("m68k: Add -ffreestanding to CFLAGS"). > > > > Hmm, yes, that should fix the problem. But why only strncmp, and why don't > > other > > Also snprintf(), IIRC. > Doesn't look like it - see below.
> > architectures suffer from the same problem ? I see that x86 uses a builtin, > > but, for example, ppc with gcc 8.3.0 also generates a call to strcmp() but > > doesn't suffer from the same problem. > > PPC doesn't #define __HAVE_ARCH_STRCMP, and thus uses strcmp() > from lib/string.c, which includes an EXPORT_SYMBOL(strcmp). > > An alternative solution is to add EXPORT_SYMBOL(strcmp) on m68k. > I think the underlying problem may be that strcmp() is static inline for m68k. That is fatal if the compiler replaces strncmp() with strcmp(). Another possible fix might be to write a 'static inline int strncmp()' function for non-coldfire code. I am not familiar enough with m68k assembler to do that, unfortunately. However, I did a simple test and added a dummy strncmp() into arch/m68k/include/asm/string.h, and it compiles clean. I think that would be a preferrable solution. Thanks, Guenter
