Gerd Hoffmann <kra...@redhat.com> writes: > Hi, > >> OK, so now I've found the bit about the magic 42; commit 7b074a22 of >> yours; recommended checking for 42 for knowing we had autosuspend; >> what's actually in the current fedora hid rules is serial!=1 - I wonder >> what others have. > > Whatever upstream systemd/udev has I guess ... > > A bit of history ... > > * First there was nothing. > * Then I added a rule to udev checking for serial == 42 > (this is in rhel-6). > * Then systemd + udev merged. > * Then I changed the rule to check for serial != 1 instead, so we can > use any serial but "1" which is the one the old broken devices had > (this is in rhel-7). March 2014 in upstream systemd. > * Then all usb power management rules where dropped from systemd (June > 2015). Which I figured today, after wondering that the rules are > gone in fedora 28. > > So, three years ago the serial number check was dropped upstream, yet I > hav't seen a single report about autosuspend issues (or cpu usage for > usb emulation going up, which is the typical symtom). > > So I figured I can stop worring that changing the serial number will > break things and just do it. > > And even if it turns out autosuspend is still an issue: I think > meanwhile we can really stop worrying about guests running in old qemu > versions with broken usb suspend (fixed in 0.13 !). If needed we can > enable autosuspend unconditionally in guests.
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