On Wed, 2026-09-02 at 10:32 +0200, Philip Lorenz via lists.openembedded.org wrote:

The mirror tarball stamp file's mtime is currently only updated on
creation / initial download. This makes it difficult to detect whether a
mirror tarball is still relevant in a given build.

Improve this by also `touch`ing the mirror tarball stamp files alongside
the sources primary stamp file.
This gets a bit tricky as we don't touch every download file at every
download, we only touch the end stamp file.

This would mean we touch mirror files and stamp files but not main
download files and I think brings things into more disparity?

This patch extends bitbake to touch the mirror tarball's `.done` file (not the mirror tarball itself) to bring it inline with regular stamp file handling.

I can also think of cases where updating the timestamp may cause things
to re-download the tarballs too since you can't know the content in
advance with many of them. This is perhaps the stronger reason not to
do this.

I'm not completely familiar with all of the fetcher details (and also couldn't find anything obvious) but in which cases would changing the mtime lead to a redownload? I'm not sure if this is still an issue given that this only updates the `.done` files of the mirror tarballs though.

The rationale behind this change is that we'd like to clean up our download caches and only keep the inputs relevant to the latest build configuration around. Using `.done` files (after executing a `bitbake --runall=fetch`) works for this as long as the mirror tarballs are freshly created. On consecutive runs their `.done` file is not touched and they are therefore deemed out of date.