| Message ID | s5h37bslwyf.wl-tiwai@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 25 May 2017 at 17:31, Takashi Iwai <tiwai@suse.de> wrote: > On Thu, 25 May 2017 17:43:44 +0200, > Cheng Sun wrote: >> >> On 25 May 2017 14:49, "Takashi Iwai" <tiwai@suse.de> wrote: >> > >> > On Wed, 24 May 2017 21:13:46 +0200, >> > Cheng Sun wrote: >> > > >> > > Hi all, >> > > >> > > The following commit (released in v1.1.4) introduced an issue where a >> > > client compiled against a 32-bit (x86) compile of alsa-lib cannot use >> > > the same dmix as a client compiled against a 64-bit alsa-lib. >> > > >> > > 1a9bd0f0448106b917ae7f7bedccfcbf6ce84802 >> > > >> > > The error message is: >> > > >> > > ALSA lib pcm_dmix.c:1077:(snd_pcm_dmix_open) unable to create IPC >> > > shm instance >> > > >> > > The following forum post (not mine) describes the symptoms of the >> > > issue in more detail (although the git commit the poster specified is >> > > not correct): >> > > >> > > >> https://forums.gentoo.org/viewtopic-p-8072290.html?sid=c2fbca45102933ddf9ca7cf8b6713e56 >> > >> > There is a known problem when you mix up two alsa-lib versions because >> > of the changes in dmix shmem struct. The solution should upgrade all >> > users. >> >> (Apologies for duplicate email --accidentally sent the first reply to the >> wrong address.) >> >> Arch Linux has upgraded both its 32 and 64 bit packages to v1.1.4, and I'm >> still experiencing this problem. >> >> While bisecting the bug I linked against two compiles of the same alsa-lib >> versions each time. >> >> Let me know if I can provide any other information. > > OK, at first to see whether it's the issue of the struct size > mismatch, check the following patch. If it is, you'll see the error > message. To be sure, check both cases: 64bit -> 32bit, and 32bit -> > 64bit. The behaviour is different for the two cases. 1) If 64bit client is started first, then the 32bit client prints the following: magic mismatch: shmptr=a15ad4f0, expected=a15ad4ec ALSA lib pcm_dmix.c:1077:(snd_pcm_dmix_open) unable to create IPC shm instance 2) If 32bit client is started first, then the 64bit client only prints: ALSA lib pcm_dmix.c:1077:(snd_pcm_dmix_open) unable to create IPC shm instance I've added some further print statements and it turns out that this is because the "return err;" on line 115 is triggered. Cheers, Cheng
diff --git a/src/pcm/pcm_direct.c b/src/pcm/pcm_direct.c --- a/src/pcm/pcm_direct.c +++ b/src/pcm/pcm_direct.c @@ -136,6 +136,7 @@ retryget: return 1; } else { if (dmix->shmptr->magic != SND_PCM_DIRECT_MAGIC) { + fprintf(stderr, "magic mismatch: shmptr=%x, expected=%x\n", (int)dmix->shmptr->magic, (int)SND_PCM_DIRECT_MAGIC); snd_pcm_direct_shm_discard(dmix); return -EINVAL; }