Akira TAGOH <akira@xxxxxxxxx> writes: > As of the discussion on the list, Keith's changes doesn't address the > original purpose - allow sharing caches on bind-mounts in flatpaks. > particularly for the case where flatpaks uses same location in > sandbox. I'm probably forgetting a bunch of context here, but I think the problem was that flatpaks have /run/host/fonts pointing to the "real" /usr/share/fonts and then a separate /usr/share/fonts of their own with a small set of fonts, and so you end up with collisions in the cache file namespace as both directories end up generating the same cache file name. > this is the reason why it can't be merged into master. So just > reverting the change that removes .uuid file only when a directory has > empty is done in master so far. if you have .uuid file prior to run > fc-cache, your issue could be worked around at this moment. for more > details, you can check what Alex Larsson said on this list. Making the build reproducible means having all content generated deterministically based only on the source package and toolchain. The current UUID files are generated randomly making them non-deterministic. For the font cache, making it reproducible requires that the keys mapping directories to cache filenames be the same each time the cache is built. This means we cannot use the current randomly generated UUID values and also have a reproducible system. I considered whether we might provide a mechanism to generate UUID values deterministically for purposes of packaging. However, this would mean that we couldn't use these same packages when creating a flatpak as the deterministic UUID values would collide if those same packages were used in the outer system. Without deterministic UUID values, I'm left with the feeling that our only available solutions involve changing how flatpaks reference fonts. If we agree that a solution to this involves changing the flatpak mechanism, I'd like to suggest that the most straightforward fix for the overall system would be to expose the external fonts using the external path names -- bind mounting the external /usr/share/fonts as /usr/share/fonts within the flatpak, and creating a new /usr/share/fonts-minimal (or whatever) to hold the fonts provided by the flatpak itself. With this change, we can simply delete the UUID code from fontconfig and go back to using global font paths as keys to the font cache database. I'd love to hear about alternative ideas which might lead to solutions that make builds involving fontconfig reproducible. I'd be happy to take even vague hints at this point; all I've got at this point are a collection of dead ends. (Also, if I've missed or forgotten something relevant, please let me know; I've re-read a lot of stuff while writing this, but surely something escaped my notice). -- -keith
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