Interestingly, I'm not getting any XFCE-related crashes when I use gnome-boxes rather than QEMU. The process that is crashing is actually X.
I got a backtrace from it: (gdb) bt -full #0 __pthread_kill_implementation (no_tid=0, signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:44 tid = <optimized out> ret = 0 pd = <optimized out> old_mask = {__val = {0}} ret = <optimized out> pd = <optimized out> old_mask = <optimized out> ret = <optimized out> tid = <optimized out> ret = <optimized out> resultvar = <optimized out> resultvar = <optimized out> __arg3 = <optimized out> __arg2 = <optimized out> __arg1 = <optimized out> _a3 = <optimized out> _a2 = <optimized out> _a1 = <optimized out> __futex = <optimized out> resultvar = <optimized out> __arg3 = <optimized out> __arg2 = <optimized out> __arg1 = <optimized out> _a3 = <optimized out> _a2 = <optimized out> _a1 = <optimized out> __futex = <optimized out> __private = <optimized out> __oldval = <optimized out> #1 __pthread_kill_internal (signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:78 No locals. #2 __GI___pthread_kill (threadid=<optimized out>, signo=signo@entry=6) at ./nptl/pthread_kill.c:89 No locals. #3 0x00007f39b123c406 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26 ret = <optimized out> #4 0x00007f39b122287c in __GI_abort () at ./stdlib/abort.c:79 save_stage = 1 act = {__sigaction_handler = {sa_handler = 0x20, sa_sigaction = 0x20}, sa_mask = {__val = {0 <repeats 16 times>}}, sa_flags = 67108868, sa_restorer = 0x7f39b123c4b0 <__restore_rt>} #5 0x0000558075c86b60 in OsAbort () at ../../../../os/utils.c:1352 No locals. #6 0x0000558075c8c319 in AbortServer () at ../../../../os/log.c:879 No locals. #7 0x0000558075c8d359 in FatalError ( f=f@entry=0x558075cbee90 "Caught signal %d (%s). Server aborting\n") at ../../../../os/log.c:1017 args = {{gp_offset = 24, fp_offset = 48, overflow_arg_area = 0x7ffd9edeb5a0, reg_save_area = 0x7ffd9edeb4d0}} args2 = {{gp_offset = 8, fp_offset = 48, overflow_arg_area = 0x7ffd9edeb5a0, reg_save_area = 0x7ffd9edeb4d0}} beenhere = 1 #8 0x0000558075c83ddc in OsSigHandler (unused=<optimized out>, sip=<optimized out>, signo=6) at ../../../../os/osinit.c:156 No locals. #9 OsSigHandler (signo=6, sip=<optimized out>, unused=<optimized out>) at ../../../../os/osinit.c:110 No locals. #10 <signal handler called> No locals. #11 __pthread_kill_implementation (no_tid=0, signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:44 tid = <optimized out> ret = 0 pd = <optimized out> old_mask = {__val = {139885759425152}} ret = <optimized out> pd = <optimized out> old_mask = <optimized out> ret = <optimized out> tid = <optimized out> ret = <optimized out> resultvar = <optimized out> resultvar = <optimized out> __arg3 = <optimized out> __arg2 = <optimized out> __arg1 = <optimized out> _a3 = <optimized out> _a2 = <optimized out> _a1 = <optimized out> __futex = <optimized out> resultvar = <optimized out> __arg3 = <optimized out> __arg2 = <optimized out> __arg1 = <optimized out> _a3 = <optimized out> _a2 = <optimized out> _a1 = <optimized out> __futex = <optimized out> __private = <optimized out> __oldval = <optimized out> #12 __pthread_kill_internal (signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:78 No locals. #13 __GI___pthread_kill (threadid=<optimized out>, signo=signo@entry=6) at ./nptl/pthread_kill.c:89 No locals. #14 0x00007f39b123c406 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26 ret = <optimized out> #15 0x00007f39b122287c in __GI_abort () at ./stdlib/abort.c:79 save_stage = 1 act = {__sigaction_handler = {sa_handler = 0x20, sa_sigaction = 0x20}, sa_mask = {__val = {94010244971792, 110, 0, 139885763323770, 0, 49245412224, 0, 140727268852584, 15975794021409362944, 5, 18446744073709550696, 11, 94010220322512, 122, 94010220302986, 94010220853328}}, sa_flags = -1322649741, sa_restorer = 0x7f39b13b677a <_nl_C_name>} #16 0x00007f39b122279b in __assert_fail_base ( fmt=0x7f39b13b9f68 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=assertion@entry=0x558075c9528a "key->initialized", file=file@entry=0x558075c99ed0 "../../../../../../include/privates.h", line=line@entry=122, function=function@entry=0x558075cb9580 <__PRETTY_FUNCTION__.7> "dixGetPrivateAddr") at ./assert/assert.c:92 str = 0x55807741bd10 "\273\2238/\205U" total = 4096 #17 0x00007f39b1233b86 in __assert_fail ( assertion=assertion@entry=0x558075c9528a "key->initialized", file=file@entry=0x558075c99ed0 "../../../../../../include/privates.h", line=line@entry=122, function=function@entry=0x558075cb9580 <__PRETTY_FUNCTION__.7> "dixGetPrivateAddr") at ./assert/assert.c:101 No locals. #18 0x0000558075c3ba25 in dixGetPrivateAddr ( key=0x558075d57020 <dri2ClientPrivateKeyRec>, privates=0x71) at ../../../../../../include/privates.h:122 __PRETTY_FUNCTION__ = "dixGetPrivateAddr" #19 0x0000558075c3dd25 in dixGetPrivateAddr (key=<optimized out>, privates=<optimized out>) at ../../../../../../include/privates.h:167 __PRETTY_FUNCTION__ = "dixGetPrivateAddr" #20 dixLookupPrivate (key=<optimized out>, privates=<optimized out>) at ../../../../../../include/privates.h:165 No locals. #21 DRI2Authenticate (client=client@entry=0x558077415b80, pScreen=<optimized out>, magic=1) at ../../../../../../hw/xfree86/dri2/dri2.c:1365 ds = <optimized out> dri2_client = <optimized out> primescreen = <optimized out> #22 0x0000558075c3eaab in ProcDRI2Authenticate (client=0x558077415b80) at ../../../../../../hw/xfree86/dri2/dri2ext.c:156 stuff = 0x5580774347b0 rep = {type = 0 '\000', pad1 = 0 '\000', sequenceNumber = 0, length = 0, authenticated = 2000771968, pad2 = 21888, pad3 = 1976678512, pad4 = 21888, pad5 = 1976679392, pad6 = 21888} pDraw = 0x5580763743a0 status = 0 #23 ProcDRI2Dispatch (client=0x558077415b80) at ../../../../../../hw/xfree86/dri2/dri2ext.c:609 stuff = 0x5580774347b0 #24 0x0000558075b0cef4 in Dispatch () at ../../../../dix/dispatch.c:550 result = <optimized out> client = 0x558077415b80 start_tick = 60 #25 0x0000558075b10f3c in dix_main (argc=11, argv=<optimized out>, envp=<optimized out>) at ../../../../dix/main.c:272 i = <optimized out> alwaysCheckForInput = {0, 1} #26 0x00007f39b1223a90 in __libc_start_call_main ( main=main@entry=0x558075afa020 <main>, argc=argc@entry=11, argv=argv@entry=0x7ffd9edec698) at ../sysdeps/nptl/libc_start_call_main.h:58 self = <optimized out> result = <optimized out> unwind_buf = {cancel_jmp_buf = {{jmp_buf = {140727268853400, -7547088934788218713, 0, 140727268853496, 94010220794264, 139885770768384, 7545894580288012455, 7579620698683130023}, mask_was_saved = 0}}, priv = {pad = {0x0, 0x0, 0x7ffd9edec698, 0x7ffd9edec698}, data = {prev = 0x0, cleanup = 0x0, canceltype = -1629567336}}} not_first_call = <optimized out> #27 0x00007f39b1223b49 in __libc_start_main_impl (main=0x558075afa020 <main>, argc=11, argv=0x7ffd9edec698, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffd9edec688) at ../csu/libc-start.c:360 No locals. #28 0x0000558075afa055 in _start () No symbol table info available. -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/2013071 Title: Session crash after initial login To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/2013071/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp