Hi Roman, On Wed, Apr 13, 2016 at 3:55 AM, Roman Bogorodskiy <bogorods...@gmail.com> wrote: > Hi, > > I was trying to get better understanding of how to properly shutdown VMs > in bhyve, but unfortunately the documentation does not provide much > details on that. > > Specifically, handbook [I] suggests to reboot a machine and then run > bhyvectl --destroy on it. > > The bhyvectl(8) manpage mentions the '--force-reset' and > '--force-poweroff' switches, but does not give details on those. > > I: https://www.freebsd.org/doc/handbook/virtualization-host-bhyve.html > > I tried all the options I know and wrote down the results. I also have > some questions, hopefully you'll be able to answer some of them. > > 1. bhyvectl --vm=$name --destroy > > * looks like hard poweroff in the guest > * the corresponding bhyve(8) process goes away > * /dev/vmm/ entry goes away > > In my experience, it's a dangerous way to shutdown a VM because > sometimes it appears it damages the image and VM fails to boot with > something like this: > > --- > Starting devd. > mode = 0100600, inum = 170269, fs = / > panic: ffs_valloc: dup alloc > cpuid = 0 > KDB: stack backtrace: > #0 0xffffffff80984e30 at kdb_backtrace+0x60 > #1 0xffffffff809489e6 at vpanic+0x126 > #2 0xffffffff809488b3 at panic+0x43 > #3 0xffffffff80b74a6e at ffs_valloc+0x84e > #4 0xffffffff80bb60ad at ufs_makeinode+0x7d > #5 0xffffffff80bb24fd at ufs_create+0x2d > #6 0xffffffff80e71841 at VOP_CREATE_APV+0xa1 > #7 0xffffffff809cd9e6 at uipc_bindat+0x346 > #8 0xffffffff809c5488 at kern_bindat+0x108 > #9 0xffffffff809c52a7 at sys_bind+0x77 > #10 0xffffffff80d4b3f7 at amd64_syscall+0x357 > #11 0xffffffff80d30adb at Xfast_syscall+0xfb > Uptime: 3s > > Dump failed. Partition too small. > --- >
Yup, this is biggest hammer you could use to shutdown a virtual machine. As you noticed, this is usually a bad thing because it does not give the guest OS an opportunity to shutdown cleanly. > 2. kill -SIGTERM $bhyve_pid > > If guest supports ACPI shutdown: > > * guest shuts down cleanly > * the corresponding bhyve(8) process terminates > * /dev/vmm entry is still here, need bhyvectl --destroy for complete > cleanup > > If guest does not support ACPI shutdown (such as doing sysctl > hw.acpi.power_button_state=NONE): > > * Nothing happens > > Q1: Is there a way to know if a guest reacted to power button but > waiting for the bhyve process to terminate? Not really, except to wait for some amount of time to give the guest a chance to shutdown. > Q2: Why it's not done via bhyvectl (it seems that it's easier for users > + don't have to overload a useful SIGTERM signal) > It seems natural to overload SIGTERM to do this. For e.g. when the host is shutting down it will send a SIGTERM to all running processes and translating this into an ACPI poweroff event for the guest allows it to shutdown cleanly. > 3. bhyvectl --vm=$name --force-poweroff > > * looks like hard poweroff in the guest > * the corresponding bhyve(8) process goes away > * /dev/vmm entry is still here, need bhyvectl --destroy for complete > cleanup > > Q: what's the practical difference with just doing --destroy right away? > 'force-poweroff' is equivalent to a hard power off on real hardware. The only practical difference between '--force-poweroff' and '--destroy' is that destroy will also remove the device node in /dev/vmm and release any memory allocated for the guest back to the host. > 4. bhyvectl --vm=$name --force-reset > > Looks very similar to item #3 with just different exit code (reboot > appears to be using 0, while shutdown and halt use 1 and 2). > > Q: what's the practical use of it? > The exit code can be used by scripts on top of 'bhyve' to decide whether to restart execution of the guest (reset) or stop completely (poweroff). > Would greatly appreciate if somebody could provide more details on that. > I guess we'll need to update Handbook with this information as well > because it needs to mention SIGTERM for ACPI shutdown at least. > Hope that helps. best Neel > Roman Bogorodskiy > _______________________________________________ > email@example.com mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-virtualization > To unsubscribe, send any mail to > "freebsd-virtualization-unsubscr...@freebsd.org" _______________________________________________ firstname.lastname@example.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-virtualization To unsubscribe, send any mail to "freebsd-virtualization-unsubscr...@freebsd.org"