The reports of kernel panics with xemacs keep rolling in; in addition to the threads in http://lists.apple.com/mhonarc/darwin-development/msg10480.html there was another report posted in http://lists.apple.com/mhonarc/darwin-development/msg10498.html And to add my two cents worth, here are MY kernel panic reports from both OS 10.1 and OS 10.1.1. Note I updated my version of xemacs in between from 21.4.3 to 21.4.5, but previous experience indicated that the xemacs version didn't matter. I've also updated the version of XDarwin from 1.0a1 to 1.0a3 and then 1.0a4, and got panics with each using emacs 21.4.3. Finally: I don't think the bug is completely reproducable. With OS 10.1, I would occasionally get kernel panics on initial launch of xemacs, but more typically only after working with xemacs for several minutes. Since going to 10.1.1 I don't have as many cases to survey, since I did my best to avoid the problem once I noted it was there. In my few experiences it again took several minutes, lots of actions, before the panic occured. So I'm guessing that when the panic occurs depends on what else is going on on the machine. -Ron Cohen- p.s. for what it is worth I am running a dual processor G4/450 with 256 MB RAM. p.p.s. Avoidance strategies: (1) run xemacs in "no-window" (-nw) mode; (2) not sure about this, but it looks like xemacs run through an ssh tunnel is OK -- that is, I ssh'ed from the mac to another machine and back, and ran xemacs (in its own window) with X11 tunnelling. ------------------ Old (OS 10.1) panic(cpu 0): lockmgr: pid -2, thread 0x 180cd04, not exclusive lock holder pid -2 thread 0x 1c8e354 unlocking, exclusive count 1 Latest stack backtrace for cpu 0: Backtrace: 0x0008122c 0x000815cc 0x00027d38 0x001831b0 0x001886c8 0x00188bf8 0x00026794 0x0008ec0c 0x0008e9a0 0x0050b13e Proceeding back via exception chain: Exception state (sv=0x0c4cd000) PC=0x70001318; MSR=0x0000f030; DAR=0x01f250ce; DSIR=0x00002004; LR=0x0008449e8; R1=0xbfffe140; XCP=0x00000030 (0xC00 - System call) Kernel version: Darwin Kernel Version 1.4: Sun Sep 9 15:39:59 PDT 2001; root:xnu/xnu-201.obj~1/RELEASE_PPC Debugger(panic) Waiting for remote debugger connection ---------------------------- New (OS 10.1.1) panic(cpu 0): lockmgr: non-zero exclusive count Latest stack backtrace for cpu 0: Backtrace: 0x000819b8 0x00081d58 0x00028520 0x001840bc 0x00187d28 0x001892dc 0x00189b78 0x00026f7c 0x0008f40c 0x001920e8 0x0018a41c 0x0018a29c Proceeding back via exception chain: Exception state (sv=0x0c4cd000) PC=0x70025CAB; MSR=0x0000f030; DAR=0x01fc7aee; DSIR=0x00002004; LR=0x0078e8e4; R1=0xbfffe800; XCP=0x00000030 (0xC00 - System call) Kernel version: Darwin Kernel Version 5.1: Tue Oct 30 00:06:34 PST 2001; root:xnu/xnu-201.5.obj~1/RELEASE_PPC Debugger(panic) Waiting for remote debugger connection