Re: [PATCH v15 23/26] sched: early boot clock

From: Dominique Martinet
Date: Thu Jan 03 2019 - 18:44:04 EST

Pavel Tatashin wrote on Thu, Jan 03, 2019:
> Could you please send the config file and qemu arguments that were
> used to reproduce this problem.

Running qemu by hand, nothing fancy e.g. this works:

# qemu-system-x86_64 -m 1G -smp 4 -drive file=/root/kvm-wrapper/disks/f2.img,if=virtio -serial mon:stdio --enable-kvm -cpu Haswell -device virtio-rng-pci -nographic

(used a specific cpu just in case but normally runnning with cpu host on
a skylake machine; can probably go older)

qemu is fedora 29 blend as is:
$ qemu-system-x86_64 --version
QEMU emulator version 3.0.0 (qemu-3.0.0-3.fc29)
Copyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers

compressed .config attached to the mail, this can likely be trimmed down
some as well but that takes more time for me..
I didn't rebuild the kernel so not 100% sure (comes from
/proc/config.gz) but it should work on a 4.20-rc2 kernel as written in
the first few lines; 857baa87b64 I referred to in another mail was
merged in 4.19-rc1 so anything past that is probably OK to reproduce...

Re-checked today with these exact options (fresh VM start; then suspend
laptop for a bit, then reboot VM):
[ 0.000000] Hypervisor detected: KVM
[ 0.000000] kvm-clock: Using msrs 4b564d01 and 4b564d00
[ 2477.907447] kvm-clock: cpu 0, msr 153a4001, primary cpu clock
[ 2477.907448] clocksource: kvm-clock: mask: 0xffffffffffffffff max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns
[ 2477.907450] tsc: Detected 2592.000 MHz processor

As offered previously, happy to help in any way.


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