id = 1922
title = "loongson3-virt machine fails to bring up secondary CPUs"
state = "opened"
created_at = "2023-10-05T17:26:24.324Z"
closed_at = "n/a"
labels = ["target: mips", "workflow::Patch available"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/1922"
host-os = "Gentoo Linux"
host-arch = "ppc64el"
qemu-version = "QEMU emulator version 8.1.1"
guest-os = "Debian 12"
guest-arch = "mips64el"
description = """When booting Debian netboot on `loongson3-virt` machine with SMP, cores other than number 0 fail to come up.  Boot without SMP is successful.

I provided the details of the first combination I tested, but I have also tested on an x86_64 host, as well as with Debian 11 (kernel `5.10.0-22-loongson-3`) on both hosts, with the same results."""
reproduce = """1.  `wget https://ftp.debian.org/debian/dists/bookworm/main/installer-mips64el/current/images/loongson-3/netboot/vmlinuz-6.1.0-10-loongson-3`
2.  `wget https://ftp.debian.org/debian/dists/bookworm/main/installer-mips64el/current/images/loongson-3/netboot/initrd.gz`
3.  `qemu-system-mips64el -M loongson3-virt -kernel vmlinuz-6.1.0-10-loongson-3 -initrd initrd.gz -append "console=ttyS0" -serial stdio -smp 2`"""
additional = """Boot is successful when removing `-smp 2` from command line.  With it present, the following error is in `dmesg` (extends to all other CPUs when a larger SMP value is passed):
```
[    2.248229] rcu: Hierarchical SRCU implementation.
[    2.248446] rcu:     Max phase no-delay instances is 1000.
[    2.647997] smp: Bringing up secondary CPUs ...
[    2.749706] Booting CPU#1...
[    7.093229] CPU1: failed to start
[    7.096508] smp: Brought up 1 node, 1 CPU
```
The boot eventually stalls after this."""