Hey Joe, Peter, On Fri, Jan 15, 2016 at 09:51:49AM -0800, Joe Perches wrote: > (cc'ing Masahiro Yamada and Jason Cooper for objdiff) > > On Fri, 2016-01-15 at 18:41 +0100, Peter Senna Tschudin wrote: ... > As far as I know, gcc has never made guarantees about > object output for the same input content. True, we may want to reach out to the folks doing reproducible builds. They may have seen/diagnosed/fixed this already. > > # But here is the interesting part. Even compiling the exact same source code > > # produces different results > > $ git checkout -- . > > $ md5sum drivers/usb/misc/sisusbvga/sisusb.c > > d6ffbd44f3f1cf81fd55ce84441ab889 drivers/usb/misc/sisusbvga/sisusb.c > > > > $ make -j4 drivers/usb/misc/sisusbvga/sisusb.o > > $ objdump -D drivers/usb/misc/sisusbvga/sisusb.o| \ > > sed "s/^[[:space:]]\+[0-9a-f]\+//" > /tmp/base_dump_again > > > > $ diff /tmp/base_dump /tmp/base_dump_again > > 9135,9136c9135,9136 > > < : 8e 4d 31 mov 0x31(%rbp),%cs > > < : 46 00 00 rex.RX add %r8b,(%rax) > > --- > > > : de 10 ficom (%rax) > > > : 33 46 00 xor 0x0(%rsi),%eax > > 9139c9139 > > < : 4b 00 00 rex.WXB add %al,(%r8) > > --- > > > : 00 4b 00 add %cl,0x0(%rbx) Well, this clearly shows that the whitespace change is a red herring. I'm just guessing here, but could you try with -j1 to see if you can still reproduce this inconsistency? Cleaning the tree between builds may also narrow down the suspects. thx, Jason. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
