[merging two replies] Hi Thomas,
> I wonder whether the "file list" in "data.tar.xz" of > https://tests.reproducible-builds.org/debian/rb-pkg/unstable/amd64/diffoscope-results/pcmemtest.html > is made from the files in the ISO or from the input files on hard disk. That can safely be ignored for our purposes. That "file list" is merely repeating that the two .debs have different contents... but they have different contents because the two ISO files within them are different; something we already know. > First an observation from digging in pcmemtest/1.5-2/build64/Makefile: > What about target grub-memtest.iso ? > It has its own xorriso run and EFI System Partition image. > I guess they need treatment for reproducibility, too. Ah, that does sound plausible, although I am now really quite out of my depth in terms of ISO/EFI/xorriso knowledge. > The other difference could be a neighbor of "directory volume label", > which Wikipedia mentions as a kind of mirror of "Partition Volume Label". > If i get it right then this is in the name and extension fields of > a "Directory entry". > The differing bytes would then be the timestamps "Create time" at offset > 0x0E and "Last Modified time" at offset 0x16. Probably the date fields at > 0x10 and 0x18 could show differences, too. > > But i am far off my usual playground now. Same. ;) > Maybe Chris already knows a good trick to enforce values for those time > and date fields in FAT filesystems. Hm. Well, I remember doing some work on dosfstools and/or mtools in order that they could generate deterministic output, but it has been quite a few years now. Did you try the --invariant flag? (There were also some patches flying around to fix mtools serialising/saving uninitialised memory as well, but I think most of them got applied, at least in Debian.) Regards, -- ,''`. : :' : Chris Lamb `. `'` la...@debian.org 🍥 chris-lamb.co.uk `-
