Pavel Dovgalyuk <pavel.dovgal...@ispras.ru> writes:
> On 07.09.2020 19:25, Alex Bennée wrote: >> >> Pavel Dovgalyuk <pavel.dovgal...@ispras.ru> writes: >> >>> On 07.09.2020 17:59, Alex Bennée wrote: >>>> >>>> Pavel Dovgalyuk <pavel.dovgal...@ispras.ru> writes: >>>> >>>>> On 07.09.2020 15:58, Alex Bennée wrote: >>>>>> >>>>>> Pavel Dovgalyuk <pavel.dovgal...@ispras.ru> writes: >>>>>> >>>>>>> From: Pavel Dovgalyuk <pavel.dovga...@ispras.ru> >>>>>>> >>>>>>> This patch adds hmp/qmp commands replay_seek/replay-seek that proceed >>>>>>> the execution to the specified instruction count. >>>>>>> The command automatically loads nearest snapshot and replays the >>>>>>> execution >>>>>>> to find the desired instruction count. >>>>>> >>>>>> Should there be an initial snapshot created at instruction 0? Using a >>>>>> separate monitor channel: >>>>> >>>>> Right, you can't go to the prior state, when there is no preceding >>>>> snapshot available. >>>> >>>> It seems creating an initial snapshot automatically would be more user >>> >>> Please take a look at 'Snapshotting' section of docs/replay.txt. >>> Reverse debugging is considered to be run with disk image (overlay) >>> and rrsnapshot option of icount, which allows creating an initial >>> VM snapshot. >> >> Given that I'm using the block device purely for VM snapshots I think it >> would be useful to document the minimal "no disk" approach - i.e. where >> the disk is only used for record/replay. >> >> However I'm still having trouble. I can record the trace with: >> >> ./qemu-system-aarch64 -cpu cortex-a53 -display none -serial stdio \ >> -machine virt -kernel zephyr.elf -net none \ >> -icount >> shift=6,align=off,sleep=off,rr=record,rrfile=record.out,rrsnapshot=rrstart \ >> -drive file=record.qcow2,if=none,id=rr \ >> -monitor telnet:127.0.0.1:4444 -S > > Can you provide your zephyr.elf image? > >> >> which shows: >> >> (qemu) info snapshots >> info snapshots >> List of snapshots present on all disks: >> ID TAG VM SIZE DATE VM CLOCK >> ICOUNT >> -- rrstart 653 KiB 2020-09-07 17:12:42 00:00:00.000 >> 0 >> >> but do I need a whole separate overlay in the replay case? I thought >> supplying snapshot to the drive would prevent the replay case >> overwriting what has been recorded but with: >> >> -icount shift=6,align=off,sleep=off,rr=replay,rrfile=record.out \ >> -drive file=record.qcow2,if=none,id=rr,snapshot > > When you provide qcow2 (overlay or not) for snapshotting, you don't need > any 'snapshot' option on drive. > >> >> but I get: >> >> (qemu) info snapshots >> info snapshots >> There is no snapshot available. >> >> so if I drop the ,snapshot from the line I can at least see the snapshot >> but continue doesn't seem to work: >> >> (qemu) info snapshots >> info snapshots >> List of snapshots present on all disks: >> ID TAG VM SIZE DATE VM CLOCK >> ICOUNT >> -- rrstart 653 KiB 2020-09-07 17:12:42 00:00:00.000 >> 0 >> (qemu) replay_break 190505 >> replay_break 190505 >> (qemu) c >> c >> (qemu) info replay >> info replay >> Replaying execution 'record.out': instruction count = 0 > > It seems, that replay hangs. Can you try removing '-S' in record command > line? That doesn't make any difference removing from both the record and replay cases. It seems to need a loadvm to start things off. I've sent you an image off list. Please let me know if you can replicate. -- Alex Bennée
