> From: Alex Bennée [mailto:alex.ben...@linaro.org] > Pavel Dovgalyuk <pavel.dovga...@ispras.ru> writes: > > > Ping? > > I started having a look but I ran into this straight away. First I > recorded a boot of the kernel: > > ./aarch64-softmmu/qemu-system-aarch64 -machine virt,graphics=on,gic- > version=3,virtualization=on -cpu cortex-a53 --serial mon:stdio -display none > -kernel > ../images/aarch64-current-linux-initrd-guest.img -icount > shift=7,rr=record,rrfile=replay.bin > > Then played back: > > ./aarch64-softmmu/qemu-system-aarch64 -machine virt,graphics=on,gic- > version=3,virtualization=on -cpu cortex-a53 --serial mon:stdio -display none > -kernel > ../images/aarch64-current-linux-initrd-guest.img -icount > shift=7,rr=replay,rrfile=replay.bin - > s -S
This looks ok, but... > And did the following on gdb: > > (gdb) i > 0x0000000040000004 in ?? () > => 0x40000004: mov x1, xzr > 0x40000008: mov x2, xzr > 0x4000000c: mov x3, xzr > (gdb) > 0x0000000040000008 in ?? () > => 0x40000008: mov x2, xzr > 0x4000000c: mov x3, xzr > 0x40000010: ldr x4, 0x40000020 > (gdb) > 0x000000004000000c in ?? () > => 0x4000000c: mov x3, xzr > 0x40000010: ldr x4, 0x40000020 > 0x40000014: br x4 > (gdb) > 0x0000000040000010 in ?? () > => 0x40000010: ldr x4, 0x40000020 > 0x40000014: br x4 > 0x40000018: .inst 0x44000000 ; undefined > (gdb) > 0x0000000040000014 in ?? () > => 0x40000014: br x4 > 0x40000018: .inst 0x44000000 ; undefined > 0x4000001c: .inst 0x00000000 ; undefined > (gdb) p/x $x4 > $1 = 0x40080000 > (gdb) reverse-stepi > warning: Remote failure reply: E14 > > Surely this is the simple case and doesn't require any snapshots for > block devices as there are none. Am I missing something? Reverse debugging requires the snapshotting. QEMU can't revert the VM state without the snapshots. You can try adding an empty qcow2 image to allow snapshotting there. Pavel Dovgalyuk
