debian bootup hangs on qemu-system-mips64el

Hi, all,

Debian/mips64el runs well on qemu-system-mips64el until I turned on smp
option with a number of 2 or higher.  See the error message below.  It
usually hangs pretty early on.

I have experimented with different CPU types (e.g., 5KEc) and different
memory amont with no avail. Does anybody have an idea?

I attached the kernel config for reference.  It appears SMP kernel configs
are enabled properly.

Thanks a lot!

Jun

qemu-system-mips64el -M malta -smp 2 -cpu MIPS64R2-generic -m 1314 -hda
hda.qcow2 -kernel vmlinux -initrd initrd.img -append 'root=/dev/sda1
console=ttyS0 nokaslr' -nographic -net
user,hostfwd=tcp::2222-:22,hostfwd=tcp::8080-:80,hostfwd=tcp::8443-:443
-net nic -serial mon:stdio
qemu-system-mips64el: warning: SPD cannot represent final 2MB of SDRAM
[    0.000000] Linux version 4.19.0-6-5kc-malta (
[email protected]) (gcc version 8.3.0 (Debian 8.3.0-6)) #1 SMP
Debian 4.19.67-2+deb10u1 (2019-09-20)
[    0.000000] earlycon: uart8250 at I/O port 0x3f8 (options '38400n8')
[    0.000000] bootconsole [uart8250] enabled
[    0.000000] CPU0 revision is: 00010000 (MIPS GENERIC QEMU)
[    0.000000] FPU revision is: 007f0000
[    0.000000] Checking for the multiply/shift bug... no.
[    0.000000] Checking for the daddiu bug... no.
[    0.000000] MIPS: machine is mti,malta
[    0.000000] Software DMA cache coherency enabled
[    0.000000] Determined physical RAM map:
[    0.000000]  memory: 0000000010000000 @ 0000000000000000 (usable)
[    0.000000]  memory: 0000000042200000 @ 0000000090000000 (usable)

[HANG FOREVER AT HERE ...]