On Mon, Dec 19, 2022 at 5:34 PM Steven Rostedt wrote: > +# Make sure 32 bit on 64 bit doesn't have stat() bugs. i don't know what you're trying to say with "32 bit on 64 bit". you mean a 32 bit binary (which ABI?) with a 64 bit kernel ? or something else ? the problem is entirely with using 32 bit filesystem interfaces. there are no other runtime requirements, either in the userland or kernel land. filesystems moved to 64 bit fields in a number of places long ago regardless of the userland or kernel ABIs. saying "32 bit" or "64 bit" is imprecise. is x86_64's x32 & aarch64's ilp32 ABI "32 bit" ? or is it "64 bit" ? what about Window's x64 (LLP64) ? https://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models https://unix.org/version2/whatsnew/lp64_wp.html usually it's better to specify ABI names and/or specific types so people know what you're trying to cater to. > +ifeq ($(shell echo '' | $(CPP) -dM - | grep __SIZEOF_LONG__ | cut -d' ' -f3),4) > + CFLAGS += -D_FILE_OFFSET_BITS=64 > +endif why do you need to sniff the size of long ? -D_FILE_OFFSET_BITS=64 should work fine regardless of the target ABI. especially because you're assuming sizeof(long) == sizeof(off_t) which is not guaranteed anywhere. on newer ABIs, like x32, sizeof(off_t) is always 64-bit while sizeof(long) is 32-bit. i don't know if there's a sizeof(long) == 8 & sizeof(off_t) == 4 ABI, but i wouldn't be surprised if it showed up. mips o64 or something wonky. afaik, the exact output of the preprocessor isn't specified by a standard, and it has changed subtly in the past. so i wouldn't rely on it in general. something like `echo __SIZEOF_LONG__ | $(CPP) -E -P - | tail -n1` would be a lot more reliable -- you aren't sniffing preprocessor internals, you're actually preprocessing something. POSIX does provide (optional) defines to try and sniff off_t sizes too: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/unistd.h.html but i think the takeaway is that this is all not worth the effort, and defining _FILE_OFFSET_BITS=64 all the time is way easier. -mike
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