On Wed, Sep 3, 2014 at 2:37 PM, Diana Craciun <diana.craciun@xxxxxxxxxxxxx> wrote: > On 09/03/2014 11:38 AM, Christoffer Dall wrote: >> >> On Wed, Sep 3, 2014 at 12:19 AM, Zbigniew Bodek <zbb@xxxxxxxxxxxx> wrote: >>> >>> 2014-09-02 9:26 GMT+02:00 Diana Craciun <diana.craciun@xxxxxxxxxxxxx>: >>>> >>>> On 09/01/2014 05:34 PM, Christoffer Dall wrote: >>>>> >>>>> On Mon, Sep 01, 2014 at 12:34:09PM +0200, Zbigniew Bodek wrote: >>>>>> >>>>>> 2014-09-01 12:16 GMT+02:00 Christoffer Dall >>>>>> <christoffer.dall@xxxxxxxxxx>: >>>>>>> >>>>>>> >>>>>>> On Monday, September 1, 2014, Zbigniew Bodek <zbb@xxxxxxxxxxxx> >>>>>>> wrote: >>>>>>>> >>>>>>>> 2014-09-01 11:56 GMT+02:00 Zbigniew Bodek <zbb@xxxxxxxxxxxx>: >>>>>>>>> >>>>>>>>> Hello Christopher, >>>>>>>>> >>>>>>>>> Please check out my answers in-line. >>>>>>>>> >>>>>>>>> Best regards >>>>>>>>> zbb >>>>>>>>> >>>>>>>>> 2014-09-01 11:00 GMT+02:00 Christoffer Dall >>>>>>>>> <christoffer.dall@xxxxxxxxxx>: >>>>>>>>>> >>>>>>>>>> On Tue, Aug 26, 2014 at 12:17:17PM +0200, Zbigniew Bodek wrote: >>>>>>>>>>> >>>>>>>>>>> 2014-08-25 21:30 GMT+02:00 Joel Schopp <joel.schopp@xxxxxxx>: >>>>>>>>>>>> >>>>>>>>>>>> On 08/25/2014 02:03 PM, Peter Maydell wrote: >>>>>>>>>>>>> >>>>>>>>>>>>> On 25 August 2014 19:49, Joel Schopp <joel.schopp@xxxxxxx> >>>>>>>>>>>>> wrote: >>>>>>>>>>>>>> >>>>>>>>>>>>>> I'm guessing that the patches Peter posted recently might have >>>>>>>>>>>>>> a >>>>>>>>>>>>>> positive effect on breakpoints and debugging with gdb. >>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> https://lists.nongnu.org/archive/html/qemu-devel/2014-08/msg01291.html >>>>>>>>>>>>> >>>>>>>>>>>>> No, those relate to running a GDB inside the QEMU TCG guest, >>>>>>>>>>>>> and won't affect an external gdb. What Zbigniew wants to do >>>>>>>>>>>>> is use the QEMU gdbstub to debug the whole guest. For >>>>>>>>>>>>> breakpoints to work in that when KVM is enabled requires >>>>>>>>>>>>> implementing support for breakpoints and the debug >>>>>>>>>>>>> interface in KVM and then the corresponding support for it >>>>>>>>>>>>> in QEMU. This is on our todo list (those with cards.linaro.org >>>>>>>>>>>>> access can find it as VIRT-116) but I don't think anybody's >>>>>>>>>>>>> working on it right now. >>>>>>>>>>>>> >>>>>>>>>>>> Thanks for the clarification. So many todos, so little time. >>>>>>>>>>> >>>>>>>>>>> Hello again, >>>>>>>>>>> >>>>>>>>>>> Thank you all very much for your answers. >>>>>>>>>>> Actually I use qemu with GDB as described here (-s -S, etc.), >>>>>>>>>>> I've >>>>>>>>>>> just posted the simplest command that I use to trigger the bug. >>>>>>>>>>> So regarding your answers I would like to ask for some more >>>>>>>>>>> clarification: >>>>>>>>>>> * Has anyone encountered/reproduce this problem on your ARM host? >>>>>>>>>>> * Any suggestion where to look in the KVM source for these kind >>>>>>>>>>> of >>>>>>>>>>> problems? >>>>>>>>>>> * Maybe there is some unstable feature that I could disable in >>>>>>>>>>> host/guest to narrow this issue? >>>>>>>>>>> >>>>>>>>>> Just checking: Are you compiling any of your kernels in Thumb-2 >>>>>>>>>> mode? >>>>>>>>>> I believe the 5250 has a hardware bug with Thumb-2 and Hyp mode. >>>>>>>> >>>>>>>> No, I am not compiling my kernels in Thumb-2 mode. >>>>>>>> >>>>>>>>>> Continuous reboots seems to work fine on my TC2. I can try giving >>>>>>>>>> it >>>>>>>>>> a >>>>>>>>>> test on an Arndale some time in the near future. Which kernel >>>>>>>>>> version >>>>>>>>>> (exact commit) are you using for your host and guest? >>>>>>>> >>>>>>>> I used v3.17-rc1 which is: 7d1311b93e58ed55f3a31cc8f94c4b8fe988a2b9 >>>>>>> >>>>>>> >>>>>>> Ok, and when you say reboot, do you mean executing 'reboot' in the >>>>>>> guest >>>>>>> or >>>>>>> are you shutting down the qemu process completely and starting a new >>>>>>> VM? >>>>>>> Do >>>>>>> you run any specific workload in the VM? >>>>>>> >>>>>>> >>>>>> I mean to execute 'reboot' command in the guest system, not exit and >>>>>> reset qemu process. >>>>>> But the issues I encounter can be also triggered when I execute guest >>>>>> machine for the first time (so without previous reboots). It is >>>>>> totally random behavior. >>>>>> I am not running anything in the VM. Just login to busybox/Ubuntu and >>>>>> reboot. >>>>>> >>>>> I just had a loop running on TC2 for hours and it works fine. Likely >>>>> to >>>>> be some specific issue with the Arndale board, I'll have a look when I >>>>> have a chance to configure my board. >>>> >>>> >>>> I saw this behaviour on Arndale board also. When I saw it I was running >>>> an >>>> older kernel so it is not something new. >>>> >>>> Diana >>>> >>> Hello, >>> >>> Thanks for the confirmation. I've also tried older kernel and the same >>> problems appear. >>> >>> Does anyone have any clues which areas to investigate in order to debug >>> this? >>> Thank you all for your help. >>> >> You should enable the KVM dynamic tracepoints in your host and figure >> out where the guest gets stuck and if there's any consistency between >> when it happens. >> > > I remember that I enabled tracepoints but it was inconsistent, the problem > did not happened in the same place. Also I have noticed that when it > returned from guest the guest PC was wrong. It had strange values of 0xc, > 0xf... > Dumping a sequence of these errors in some text file, pastebin or something for me to look at would be a great help in starting to track down this issue. -Chritoffer _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
