[Qemu-devel] arm: vexpress SMP broken?

[Peter Crosthwaite]

Hi All,

I'm having trouble getting SMP to work on the vexpress platform. Looks
like a regression.

Following these instructions using latest QEMU:

http://wiki.ecg.rice.edu/doku.php?id=xzl:tutorial:arm_qemu

section "Try ARM Linux prebuilt image on QEMU" with addition of "-smp
2" argument, it fails to probe secondary CPUs:

./qemu-build/arm-softmmu/qemu-system-arm -kernel ../tmp/uImage -M
vexpress-a9 -cpu cortex-a9 -serial mon:stdio -m 1024 -initrd ./initrd
-append 'root=/dev/mmcblk0p2 rw mem=1024M raid=noautodetect
console=ttyAMA0,38400n8 rootwait vmalloc=256MB devtmpfs.mount=0' -sd
vexpress-a9-nano.img -nographic -smp 2
Uncompressing Linux... done, booting the kernel.
[    0.000000] Booting Linux on physical CPU 0
...
[    0.510327] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[    0.512100] Calibrating local timer... 99.40MHz.
[    0.565227] hw perfevents: enabled with ARMv7 Cortex-A9 PMU driver,
1 counters available
[    1.090777] CPU1: Booted secondary processor
[    8.655956] CPU1: failed to come online
[    8.680134] Brought up 1 CPUs
[    8.680394] SMP: Total of 1 processors activated (609.07 BogoMIPS).

A bisection points at:

commit 6d327171551a12b937c5718073b9848d0274c74d
Author: Alex Bligh <address@hidden>
Date:   Wed Aug 21 16:02:59 2013 +0100

    aio / timers: Remove alarm timers

    Remove alarm timers from qemu-timers.c now we use g_poll / ppoll
    instead.

    Signed-off-by: Alex Bligh <address@hidden>
    Signed-off-by: Stefan Hajnoczi <address@hidden>

Using the parent to this commit (latest good revision =
54904d2a9165bd34dee0f076826b308be2498fe0) gives:

[    0.719852] CPU1: Booted secondary processor
[    0.859186] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[    0.899732] CPU1: Unknown IPI message 0x1
[    0.922516] Brought up 2 CPUs
[    0.922768] SMP: Total of 2 processors activated (1209.54 BogoMIPS).

This a know issue or anyone have any insights?

Regards,
Peter