With the kernel 4.7.0 my Debian testing Xfce system works fine. But with kernel 4.8.1 from kernel.org Rosegarden do not play software synth tracks but only audio vocal track can be heard but the song does not go forward. If I press the play button many times, the song is played backwards step by step. I have Asus A88XM-E motherboard. Audio shows with dmesg as follows: [ 2.603284] snd_hda_codec_realtek hdaudioC0D0: autoconfig for ALC887-VD: line_outs=1 (0x14/0x0/0x0/0x0/0x0) type:line [ 2.603288] snd_hda_codec_realtek hdaudioC0D0: speaker_outs=0 (0x0/0x0/0x0/0x0/0x0) [ 2.603291] snd_hda_codec_realtek hdaudioC0D0: hp_outs=1 (0x1b/0x0/0x0/0x0/0x0) [ 2.603293] snd_hda_codec_realtek hdaudioC0D0: mono: mono_out=0x0 [ 2.603294] snd_hda_codec_realtek hdaudioC0D0: dig-out=0x11/0x0 [ 2.603296] snd_hda_codec_realtek hdaudioC0D0: inputs: [ 2.603298] snd_hda_codec_realtek hdaudioC0D0: Front Mic=0x19 [ 2.603300] snd_hda_codec_realtek hdaudioC0D0: Rear Mic=0x18 [ 2.603301] snd_hda_codec_realtek hdaudioC0D0: Line=0x1a The problem might be in also in timer module or somewhere else in the kernel. My sw synths are FluidSynth and ZASF. No debug tracing available because I use non-debug kernels. Jack2 is the latest one, version 1.9.10. I found the same problem in the 4.8.0-rc8 kernel too.
Tested more kernels from kernel.org. 4.7.8 ok, 4.8.2 same problem
Same thing happens with external midi synths. Maybe some timer value in the kernel has changed its sign.
I solved this problem by selecting timer source as PCM-Playback in the Edit->Preferences->Midi dialog. Option Auto does not work and selecting HR timer hangs the pc.
There have been indeed a few fixes related to ALSA timer interface. The relevant commits between 4.7 and 4.8 are: 816f318b2364262a51024096da7ca3b84e78e3b5 ALSA: rawmidi: Fix possible deadlock with virmidi registration 9f8a7658bcafb2a7853f7a2eae8a94e87e6e695b ALSA: timer: Fix zero-division by continue of uninitialized instance 11749e086b2766cccf6217a527ef5c5604ba069c ALSA: timer: fix NULL pointer dereference in read()/ioctl() race 8ddc05638ee42b18ba4fe99b5fb647fa3ad20456 ALSA: timer: fix NULL pointer dereference on memory allocation failure 3915bf2946520ace5bcc8104717a3cb0452d7430 ALSA: seq_timer: use monotonic times internally Could you try to revert one by one from the first to the last on top of 4.8.0 kernel? My rough guess is the second one, but it might be the last one, too.
OK, spotted out. It's the last one. The fix patch is below.
Created attachment 242671 [details] Fix patch
The fix got merged to upstream 4.9.