Hi Chris, On Thu, Jan 23, 2020 at 01:00:39PM +0100, Chris Lamb wrote: > > Most likely, it can be fixed by adding -D_FILE_OFFSET_BITS=64 to the > > CFLAGS. > > Happy to make this change in Debian, but do you believe this is > suitable for inclusion upstream too?
First of all, this is an unverified expectation. I don't know whether it fixes the issue, it just is a guess for the cause. Assuming that the guess is correct, I think upstream would want change the behaviour of configure along the lines: * Compute sizeof(off_t). * If that happens to be >= 8, all is well. * Compute sizeof(off_t) again with -D_FILE_OFFSET_BITS=64 temporarily added to CFLAGS. * If it becomes larger, keep the flag, otherwise print some warning about not working with large images. A difficulty arises as AC_CHECK_SIZEOF caches its result, so the second check would likely look something like: AC_CHECK_SIZEOF([off_t_with_file_offset_bits64],,[AC_INCLUDES_DEFAULT #define off_t_with_file_offset_bits64 off_t ]) I also think that this problem could be tested for in an autopkgtest. The code can be based on this. truncate -s $((1 << 26)) image /sbin/mkfs.vfat image dd if=image of=image2 bs=1M seek=2048 conv=sparse mdir -i image2@@2048M The last command fails on armhf, but not on amd64. Do we run autopktests on any 32bit systems? Hope this helps. Helmut
