Today I wrote some patches (for libguestfs) which add an experimental UML backend:
https://www.redhat.com/archives/libguestfs/2013-August/msg00005.html There are some observations from this. * 'ubd<N>=cow,original' is not parsed correctly. This was reported a while back and I'm seeing the same thing with the latest kernel from git: http://thread.gmane.org/gmane.linux.uml.devel/13556 If I have some time I'll have a go at fixing this since it seems like a simple regression. * I'm trying to use a serial port to communicate between guest and host, using ssl3=fd:<N>. This causes the Linux process to crash soon (but not immediately) after the guest has opened /dev/ttyS3: spurious interrupt in ubd_handler, err = -4 I've put the full call trace at the end of the email because it's quite long[1]. This was also reported before, although the suggested patch did not fix it: http://marc.info/?l=linux-kernel&m=123242364211797&w=2 I wonder if anyone has used the fd:<N> option in anger? I will try using a Unix domain socket and see if it makes a difference. * UML is pretty fast! It's certainly faster (by a factor of > 5) than spinning up a lightweight KVM VM. Rich. [1] Call trace spurious interrupt in ubd_handler, err = -4 Modules linked in: Pid: 1614169860, comm: Not tainted 3.11.0-rc4-00103-g6c2580c RIP: 0033:[<000000006001db74>] RSP: 0000000080ca9f98 EFLAGS: 00010206 RAX: 0000000000000008 RBX: 0000000000000008 RCX: 0000003f2cae6970 RDX: 0000000000000000 RSI: 0000000080ca9fb0 RDI: 0000000000000005 RBP: 0000000080ca9fe8 R08: 0000000080ca9ed8 R09: 0000000080ca9e40 R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000001000 R13: 0000000080e867c4 R14: 0000000000000001 R15: 68c00000000080ea Call Trace: 80ca9538: [<600151ac>]------------[ cut here ]------------ WARNING: CPU: 0 PID: 6 at block/blk.h:210 generic_make_request_checks+0x1aa/0x234() BUG: recent printk recursion! 80ca9648: [<60022207>] sig_handler_common+0x8c/0xa2 80ca96d0: [<6001db74>] io_thread+0x63/0x243 80ca9988: [<600222c2>] sig_handler+0x2e/0x39 80ca99a8: [<60021f33>] hard_handler+0x83/0xab 80ca9aa8: [<6001db74>] io_thread+0x63/0x243 80ca9d88: [<60021eb0>] hard_handler+0x0/0xab 80ca9f70: [<60020308>] os_seek_file+0x11/0x27 80ca9f80: [<6002032a>] os_read_file+0xc/0x1f 80ca9f90: [<6001db3b>] io_thread+0x2a/0x243 Kernel panic - not syncing: Segfault with no mm CPU: 0 PID: 1614169860 Comm: Not tainted 3.11.0-rc4-00103-g6c2580c #3 Modules linked in: Pid: 1614169860, comm: Not tainted 3.11.0-rc4-00103-g6c2580c RIP: 0033:[<0000000060026715>] RSP: 0000000080ca9328 EFLAGS: 00010246 RAX: 0000000080ca9398 RBX: 00000000602d2460 RCX: 0000000080ca8000 RDX: 0000000000000008 RSI: 636f6c6e6f6e5f88 RDI: 0000000080ca9398 RBP: 0000000080ca9350 R08: 636f6c6e6f6e5f70 R09: 636f6c6e6f6e5f70 R10: 0000003f2ca892da R11: 0000003f2ca892da R12: 000000006026b27c R13: 000000006001db74 R14: 0000000000000004 R15: 0000000000000000 Call Trace: 80ca88b8: [<600151ac>] segv+0x66/0x241 80ca8988: [<600153e9>] segv_handler+0x62/0x6c 80ca89c8: [<60022207>] sig_handler_common+0x8c/0xa2 80ca89e0: [<6001db74>] io_thread+0x63/0x243 80ca8a50: [<60026715>] memcpy+0xb5/0x140 80ca8d08: [<600222c2>] sig_handler+0x2e/0x39 80ca8d28: [<60021f33>] hard_handler+0x83/0xab 80ca8d58: [<6001db74>] io_thread+0x63/0x243 80ca8dd0: [<6001db74>] io_thread+0x63/0x243 80ca8e28: [<60026715>] memcpy+0xb5/0x140 80ca90e8: [<60017226>] generic_write+0xf/0x38 80ca9108: [<600172f9>] generic_console_write+0x3e/0x165 80ca9288: [<6004c396>] vprintk_emit+0x2dd/0x2ee 80ca92d8: [<6001db74>] io_thread+0x63/0x243 80ca92f8: [<601edf38>] printk+0x97/0x99 80ca9308: [<60015eff>] copy_from_user+0x36/0x8a 80ca9328: [<60015eff>] copy_from_user+0x36/0x8a 80ca9358: [<600699d4>] __probe_kernel_read+0x3c/0x6d 80ca9368: [<6003f2ac>] probe_kthread_data+0x29/0x2f 80ca9388: [<6003becc>] print_worker_info+0x66/0x124 80ca93f8: [<6004d204>] dump_stack_print_info+0xa6/0xaf 80ca9428: [<601efbeb>] dump_stack+0xe/0x19 80ca9438: [<601ed8b7>] panic+0xf7/0x1e4 80ca9490: [<60056982>] __module_text_address+0xd/0x4d 80ca94a8: [<6005a007>] is_module_text_address+0x9/0x11 80ca94b8: [<6003cd40>] __kernel_text_address+0x26/0x49 80ca94d8: [<60014146>] show_trace+0x8e/0x95 80ca9508: [<60026491>] show_regs+0x27/0x2a 80ca9520: [<6001db74>] io_thread+0x63/0x243 80ca9538: [<6001524f>] segv+0x109/0x241 80ca9608: [<600153e9>] segv_handler+0x62/0x6c 80ca9628: [<60022169>] unblock_signals+0x4a/0x5c 80ca9648: [<60022207>] sig_handler_common+0x8c/0xa2 80ca96d0: [<6001db74>] io_thread+0x63/0x243 80ca9988: [<600222c2>] sig_handler+0x2e/0x39 80ca99a8: [<60021f33>] hard_handler+0x83/0xab 80ca9aa8: [<6001db74>] io_thread+0x63/0x243 80ca9d88: [<60021eb0>] hard_handler+0x0/0xab 80ca9f70: [<60020308>] os_seek_file+0x11/0x27 80ca9f80: [<6002032a>] os_read_file+0xc/0x1f 80ca9f90: [<6001db3b>] io_thread+0x2a/0x243 Kernel panic - not syncing: Segfault with no mm Modules linked in: Pid: 1614169860, comm: Not tainted 3.11.0-rc4-00103-g6c2580c RIP: 0000:[<000001a400000004>] RSP: 0000000000000000 EFLAGS: 6002e720 RAX: 000000006002e770 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000602706ae RBP: 0000000000000000 R08: 0000000000000000 R09: 000001a400000004 R10: 00000000602d04ac R11: 000000006027069b R12: 0000000000000000 R13: 000000006002e720 R14: 0000000000000000 R15: 000001a400000004 Call Trace: 80ca8748: [<6001564c>] panic_exit+0x2b/0x41 80ca8758: [<6015a3ac>] vsnprintf+0xd0/0x431 80ca8768: [<600427c7>] notifier_call_chain+0x39/0x5c 80ca8790: [<60026715>] memcpy+0xb5/0x140 80ca87a8: [<60042804>] atomic_notifier_call_chain+0xf/0x11 80ca87b8: [<601ed8d2>] panic+0x112/0x1e4 80ca8810: [<60056982>] __module_text_address+0xd/0x4d 80ca8828: [<6005a007>] is_module_text_address+0x9/0x11 80ca8838: [<6003cd40>] __kernel_text_address+0x26/0x49 80ca8858: [<60014146>] show_trace+0x8e/0x95 80ca8888: [<60026491>] show_regs+0x27/0x2a 80ca88a0: [<60026715>] memcpy+0xb5/0x140 80ca88b8: [<6001524f>] segv+0x109/0x241 80ca8988: [<600153e9>] segv_handler+0x62/0x6c 80ca89c8: [<60022207>] sig_handler_common+0x8c/0xa2 80ca89e0: [<6001db74>] io_thread+0x63/0x243 -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into KVM guests. http://libguestfs.org/virt-v2v ------------------------------------------------------------------------------ Get 100% visibility into Java/.NET code with AppDynamics Lite! It's a free troubleshooting tool designed for production. Get down to code-level detail for bottlenecks, with <2% overhead. Download for free and get started troubleshooting in minutes. http://pubads.g.doubleclick.net/gampad/clk?id=48897031&iu=/4140/ostg.clktrk _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
