On 2011-10-10 09:47, Wen Congyang wrote: > At 10/10/2011 03:22 PM, Jan Kiszka Write: >> On 2011-10-10 09:17, Wen Congyang wrote: >>> At 10/10/2011 03:01 PM, Jan Kiszka Write: >>>> On 2011-10-10 08:59, Wen Congyang wrote: >>>>> At 10/10/2011 02:52 PM, Jan Kiszka Write: >>>>>> On 2011-10-10 04:21, Wen Congyang wrote: >>>>>>> At 10/09/2011 06:23 PM, Richard W.M. Jones Write: >>>>>>>> On Sun, Oct 09, 2011 at 10:49:57AM +0200, Jan Kiszka wrote: >>>>>>>>> As explained in the other replies: It is way more future-proof to use >>>>>>>>> an >>>>>>>>> interface for this which was designed for it (remote gdb) instead of >>>>>>>>> artificially relaxing reasonable constraints of the migration >>>>>>>>> mechanism >>>>>>>>> plus having to follow that format with the post-processing tool. >>>>>>>> >>>>>>>> Any interface that isn't "get this information off my production >>>>>>>> server *now*" so that I can get the server restarted, and send it to >>>>>>>> an expert to analyse -- is a poor interface, whether it was designed >>>>>>>> like that or not. Perhaps we don't have the right interface at all, >>>>>>>> but remote gdb is not it. >>>>>>> >>>>>>> What about the following idea? >>>>>>> >>>>>>> Introduce a new monitor command named dump, and this command accepts a >>>>>>> filename. >>>>>>> We can use almost all migration's code. We use this command to dump >>>>>>> guest's >>>>>>> memory, so there is no need to check whether the guest has a >>>>>>> unmigratable device. >>>>>> >>>>>> I do not want to reject this proposal categorically, but I would like to >>>>>> see the gdb path fail /wrt essential requirements first. So far I don't >>>>>> see it would. >>>>> >>>>> ‘gdb path fail /wrt essential requirements’ >>>>> >>>>> what does it mean? >>>> >>>> That you explain why reading reading memory and processor states via the >>>> remote gdb interface and dumping it into a proper core file cannot be >>>> made working for you. >>> >>> First, I think crash can not analyze such core file. But it is not very >>> important. >>> >>> What is remote gdb interface? >> >> man qemu -> gdb. >> >>> Do you mean that: the supporter uses gdb from another machine >> >> Or locally. There are various transports possible. >> >>> to connect to customer's machine and get the data? If so, this way can not >>> be >>> used when the customer needs to dump the guest's memory automatically when >>> watchdog timeouts. >> >> It is just another channel that can conceptually be used like the >> monitor, by a management app like libvirt, directly or indirectly via a >> scripted gdb frontend, or also by a human who wants to save some ongoing >> gdb session for later analysis. This dual use make such an approach the >> preferred one. > > Is the following is right? > > 1. execute the monitor command 'gdbserver' > 2. run gdb and then 'target remote :1234'
Yep. > > But, unfortunately, the monitor command gdbserver does not exit when we use > json to connect to monitor. You mean via human-monitor-command (gdbserver is not a qmp command)? Would be a bug. Jan
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