* Gerd Hoffmann (kra...@redhat.com) wrote: > 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.
OK, so what about the other question - which serial number do we end up with after this patch; do we get the 89126/28754/68284 or do we get the path based one from your change that calls usb_desc_create_serial? Dave > cheers, > Gerd > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
