Re: QEMU hangs with smp option on ubuntu 16.04 ... any fix?

I guess you can have a try of new version of qemu.
I am using qemu user to build the whole Debian archive,
and I feel that newer version has less bug.
Jun Sun <[email protected]> 于2018年10月8日周一 上午5:01写道：
>
> So I tried to rebuild kernel with debian kernel source and debian kernel config, except that I added CONFIG_MIPS_MT_SMP, which in turn turns on CONFIG_SMP.
>
> This new kernel boots all the way to user land and I could see CPU1 is brought up.  However, it crashes early after it enters userland.  It gives some cryptic error messages.  See some of them below.
>
> Did I do anything wrongly?  Would appreciate any pointers.
>
> Jun
>
> ==================
> ubuntu@ip-10-1-3-178:~/mipseb$ ./start-mipseb.sh
> [    0.000000] Linux version 4.9.0-7-4kc-malta-rt76 (ubuntu@ip-10-1-3-178) (gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.9) ) #9 SMP Sun Oct 7 15:54:10 UTC 2018
> [    0.000000] earlycon: uart8250 at I/O port 0x3f8 (options '38400n8')
> [    0.000000] bootconsole [uart8250] enabled
> [    0.000000] MIPS CPS SMP unable to proceed without a CM
> [    0.000000] CPU0 revision is: 00019500 (MIPS 34Kc)
> [    0.000000] FPU revision is: 00739500
> [    0.000000] MIPS: machine is mti,malta
> [    0.000000] Software DMA cache coherency enabled
> [    0.000000] Determined physical RAM map:
> [    0.000000]  memory: 10000000 @ 00000000 (usable)
> [    0.000000]  memory: 21fff000 @ 90000000 (usable)
> [    0.000000] Initial ramdisk at: 0x80af0000 (19033219 bytes)
> [    0.000000] Reserving 0MB of memory at 0MB for crashkernel
> [    0.000000] Detected 1 available secondary CPU(s)
> [    0.000000] Primary instruction cache 2kB, VIPT, 2-way, linesize 16 bytes.
> [    0.000000] Primary data cache 2kB, 2-way, VIPT, no aliases, linesize 16 bytes
> [    0.000000] Zone ranges:
> [    0.000000]   DMA      [mem 0x0000000000000000-0x0000000000ffffff]
> [    0.000000]   Normal   [mem 0x0000000001000000-0x000000000fffffff]
> [    0.000000] Movable zone start for each node
> [    0.000000] Early memory node ranges
> [    0.000000]   node   0: [mem 0x0000000000000000-0x000000000fffffff]
> [    0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x000000000fffffff]
> [    0.000000] percpu: Embedded 15 pages/cpu @81f5d000 s32208 r8192 d21040 u61440
> [    0.000000] Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 64960
> [    0.000000] Kernel command line: rd_start=0xffffffff80af0000 rd_size=19033219 root=/dev/sda1 console=ttyS0 nokaslr
> [    0.000000] PID hash table entries: 1024 (order: 0, 4096 bytes)
> [    0.000000] Dentry cache hash table entries: 32768 (order: 5, 131072 bytes)
> [    0.000000] Inode-cache hash table entries: 16384 (order: 4, 65536 bytes)
> [    0.000000] Writing ErrCtl register=00000000
> [    0.000000] Readback ErrCtl register=00000000
> [    0.000000] Memory: 229708K/262144K available (6445K kernel code, 574K rwdata, 1348K rodata, 1480K init, 302K bss, 32436K reserved, 0K cma-reserved)
> [    0.000000] Hierarchical RCU implementation.
> [    0.000000] Build-time adjustment of leaf fanout to 32.
> [    0.000000] NR_IRQS:256
> [    0.000000] CPU frequency 200.00 MHz
> [    0.000000] clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112674795 ns
> [    0.000174] sched_clock: 32 bits at 99MHz, resolution 10ns, wraps every 21474915322ns
> [    0.009984] Console: colour dummy device 80x25
> [    0.011080] Calibrating delay loop... 1142.78 BogoMIPS (lpj=2285568)
> [    0.034914] pid_max: default: 32768 minimum: 301
> [    0.036331] Security Framework initialized
> [    0.036630] Yama: disabled by default; enable with sysctl kernel.yama.*
> [    0.037709] AppArmor: AppArmor disabled by boot time parameter
> [    0.039095] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
> [    0.039549] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
> [    0.051724] ftrace: allocating 19328 entries in 38 pages
> [    0.119358] Performance counters: No available PMU.
> [    0.139167] Primary instruction cache 2kB, VIPT, 2-way, linesize 16 bytes.
> [    0.139240] Primary data cache 2kB, 2-way, VIPT, no aliases, linesize 16 bytes
> [    0.142776] CPU1 revision is: 00019500 (MIPS 34Kc)
> [    0.142795] FPU revision is: 00739500
> [    3.388816] Synchronize counters for CPU 1:
> [    3.388834] done.
> [    3.391435] Brought up 2 CPUs
> [    3.441632] devtmpfs: initialized
> [    3.484928] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
> [    3.485834] futex hash table entries: 512 (order: 3, 32768 bytes)
> [    3.539332] NET: Registered protocol family 16
> [    3.557040] pm-cps: no CM, non-coherent states unavailable
> [    4.943802] vgaarb: loaded
> [    4.945261] SCSI subsystem initialized
> [    4.947839] PCI host bridge to bus 0000:00
> [    4.948526] pci_bus 0000:00: root bus resource [mem 0x10000000-0x17ffffff]
> [    4.948991] pci_bus 0000:00: root bus resource [io  0x1000-0x1fffff]
> [    4.949558] pci_bus 0000:00: root bus resource [??? 0x00000000 flags 0x0]
> [    4.950012] pci_bus 0000:00: No busn resource found for root bus, will use [bus 00-ff]
> [    4.951733] pci 0000:00:00.0: [Firmware Bug]: reg 0x14: invalid BAR (can't size)
> [    4.952198] pci 0000:00:00.0: [Firmware Bug]: reg 0x18: invalid BAR (can't size)
> [    4.952636] pci 0000:00:00.0: [Firmware Bug]: reg 0x1c: invalid BAR (can't size)
> [    4.953074] pci 0000:00:00.0: [Firmware Bug]: reg 0x20: invalid BAR (can't size)
> [    4.953530] pci 0000:00:00.0: [Firmware Bug]: reg 0x24: invalid BAR (can't size)
> [    4.956039] pci 0000:00:0a.1: legacy IDE quirk: reg 0x10: [io  0x01f0-0x01f7]
> [    4.956495] pci 0000:00:0a.1: legacy IDE quirk: reg 0x14: [io  0x03f6]
> [    4.956903] pci 0000:00:0a.1: legacy IDE quirk: reg 0x18: [io  0x0170-0x0177]
> [    4.957337] pci 0000:00:0a.1: legacy IDE quirk: reg 0x1c: [io  0x0376]
> [    4.959035] pci 0000:00:0a.3: quirk: [io  0x1000-0x103f] claimed by PIIX4 ACPI
> [    4.959507] pci 0000:00:0a.3: quirk: [io  0x1100-0x110f] claimed by PIIX4 SMB
> [    4.961180] vgaarb: device added: PCI:0000:00:12.0,decodes=io+mem,owns=none,locks=none
> [    4.962671] pci 0000:00:12.0: BAR 0: assigned [mem 0x10000000-0x11ffffff pref]
> [    4.963235] pci 0000:00:0b.0: BAR 6: assigned [mem 0x12000000-0x1203ffff pref]
> [    4.963693] pci 0000:00:12.0: BAR 6: assigned [mem 0x12040000-0x1204ffff pref]
> [    4.964147] pci 0000:00:12.0: BAR 1: assigned [mem 0x12050000-0x12050fff]
> [    4.964587] pci 0000:00:0a.2: BAR 4: assigned [io  0x1040-0x105f]
> [    4.964964] pci 0000:00:0b.0: BAR 0: assigned [io  0x1060-0x107f]
> [    4.965335] pci 0000:00:0b.0: BAR 1: assigned [mem 0x12051000-0x1205101f]
> [    4.965743] pci 0000:00:0a.1: BAR 4: assigned [io  0x1080-0x108f]
> [   16.002004] clocksource: Switched to clocksource MIPS
> [   17.511363] VFS: Disk quotas dquot_6.6.0
> [   18.010327] VFS: Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
> [   18.020783] random: fast init done
> [   20.044699] NET: Registered protocol family 2
> [   21.544726] TCP established hash table entries: 2048 (order: 1, 8192 bytes)
> [   21.545391] TCP bind hash table entries: 2048 (order: 2, 16384 bytes)
> [   21.545894] TCP: Hash tables configured (established 2048 bind 2048)
> [   21.546944] UDP hash table entries: 256 (order: 1, 8192 bytes)
> [   21.547382] UDP-Lite hash table entries: 256 (order: 1, 8192 bytes)
> [   22.043069] NET: Registered protocol family 1
> [   22.044032] PCI: Enabling device 0000:00:0a.2 (0000 -> 0001)
> [   22.049627] Unpacking initramfs...
> [   23.318000] Freeing initrd memory: 18584K
> [   24.820672] audit: initializing netlink subsys (disabled)
> [   24.821840] audit: type=2000 audit(1538945938.020:1): initialized
> [   24.826730] workingset: timestamp_bits=14 max_order=16 bucket_order=2
> [   24.828367] zbud: loaded
> [   26.426847] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 251)
> [   26.428457] io scheduler noop registered
> [   26.428881] io scheduler deadline registered
> [   27.425910] io scheduler cfq registered (default)
> [   27.427252] PCI: Enabling device 0000:00:12.0 (0000 -> 0002)
> [   27.429071] cirrusfb 0000:00:12.0: Cirrus Logic chipset on PCI bus, RAM (4096 kB) at 0x10000000
> [   27.666740] Console: switching to colour frame buffer device 80x30
> [   27.688486] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
> [   27.695375] console [ttyS0] disabled
> [   27.720304] serial8250.0: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
> [   27.721708] console [ttyS0] enabled
> [   27.721708] console [ttyS0] enabled
> [   27.722687] bootconsole [uart8250] disabled
> [   27.722687] bootconsole [uart8250] disabled
> [   27.747064] serial8250.0: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 115200) is a 16550A
> [   27.751639] mousedev: PS/2 mouse device common for all mice
> [   27.754282] rtc_cmos 70.rtc: rtc core: registered rtc_cmos as rtc0
> [   27.755165] rtc_cmos 70.rtc: alarms up to one day, 242 bytes nvram
> [   27.756946] ledtrig-cpu: registered to indicate activity on CPUs
> [   29.497742] NET: Registered protocol family 10
> [   30.497515] mip6: Mobile IPv6
> [   30.497841] NET: Registered protocol family 17
> [   30.498219] mpls_gso: MPLS GSO support
> [   30.500361] registered taskstats version 1
> [   30.501270] zswap: loaded using pool lzo/zbud
> [   30.503611] ima: No TPM chip found, activating TPM-bypass!
> [   30.504203] ima: Allocated hash algorithm: sha256
> [   30.996619] rtc_cmos 70.rtc: setting system clock to 2018-10-07 20:59:23 UTC (1538945963)
> [   31.022045] Freeing unused kernel memory: 1480K
> [   31.022366] This architecture does not have kernel memory protection.
> Loading, please wait...
> [    3.889843] INFO: rcu_sched self-detected stall on CPU
> [    3.890535] 0-...: (2 ticks this GP) idle=385/2/0 softirq=0/0 fqs=0
> [    3.891233] (t=5353 jiffies g=-299 c=-300 q=2017)
> [    3.891755] rcu_sched kthread starved for 5353 jiffies! g4294966997 c4294966996 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x1
> [    3.892941] rcu_sched       S    0     7      2 0x00100000
> [    3.893553] Stack : 81f642c0 8fca8280 8fcfc900 8fcfd1c0 8fcfc900 807562b4 80741f44 81f642c0
> [    3.894325]         81f642f8 8099d2c0 808b1220 808b0000 81f642f8 00040900 8fcfc900 8fcffdf4
> [    3.895234]         81f5f680 808b0000 81f5f680 808b0000 00000000 ffffffff 00000000 80741f44
> [    3.895989]         8fcffdf4 809a0000 808b0000 fffee4ed fffee4ed 807454f8 8fcffe98 808b0000
> [    3.896724]         808c2650 801921c4 00000001 81f5f680 00000001 00000000 81f5f930 fffee4ed
> [    3.897360]         ...
> [    3.897850] Call Trace:
> [    3.898314] [<80741a78>] __schedule+0x62c/0xaa8
> [    3.898835] [<80741f44>] schedule+0x50/0xf0
> [    3.899135] [<807454f8>] schedule_timeout+0x1ec/0x484
> [    3.899493] [<801c1580>] rcu_gp_kthread+0x5bc/0xa90
> [    3.899840] [<80161a74>] kthread+0xfc/0x114
> [    3.900139] [<80106a58>] ret_from_kernel_thread+0x14/0x1c
> [    3.900774] Task dump for CPU 0:
> [    3.901018] swapper/0       R  running task        0     0      0 0x00100004
> [    3.901530] Stack : 80aa9410 00000000 80ab0000 801ac6b8 00000000 00000000 80ab0000 801ac6b8
> [    3.902139]         0000001d 00000006 00000006 00000000 00000000 00000000 0000000a 00000000
> [    3.902790]         00000000 80aa9412 0000001d 80aa9878 808b0000 808c24c0 808b0000 808b0808
> [    3.903508]         00000140 808b0000 00000000 00000000 00000000 00000000 00000000 00000000
> [    3.904194]         00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> [    3.904857]         ...
> [    3.905052] Call Trace:
> [    3.905251] [<8010d8d0>] show_stack+0xa0/0xc4
> [    3.905595] [<8027c2e4>] rcu_dump_cpu_stacks+0xe8/0x128
> [    3.905971] [<801c274c>] rcu_check_callbacks+0x854/0xa20
> [    3.906344] [<801ca378>] update_process_times+0x4c/0x80
> [    3.906946] [<801e1928>] tick_sched_handle.isra.4+0x34/0x94
> [    3.907390] [<801e19f8>] tick_sched_timer+0x70/0xdc
> [    3.907782] [<801cb9b4>] __hrtimer_run_queues+0x144/0x3d8
> [    3.908173] [<801cc6cc>] hrtimer_interrupt+0x118/0x338
> [    3.908543] [<80112580>] c0_compare_interrupt+0x8c/0xe4
> [    3.908920] [<801aee0c>] __handle_irq_event_percpu+0x8c/0x2a0
> [    3.909330] [<801af078>] handle_irq_event_percpu+0x58/0xbc
> [    3.909723] [<801b4820>] handle_percpu_irq+0x98/0xc8
> [    3.910083] [<801ae100>] generic_handle_irq+0x50/0x6c
> [    3.910459] [<80747e48>] do_IRQ+0x28/0x34
> [    3.910771] [<804a3800>] plat_irq_dispatch+0x64/0xb8
> [    3.911133] [<80106f68>] except_vec_vi_end+0xb8/0xc4
> [    3.911531] Task dump for CPU 1:
> [    3.911761] init            R  running task        0    68      1 0x08100020
> [    3.912254] Stack : 808e0000 8082745c 8ca86300 80367030 00002017 802b8e60 80aa0000 802f79a4
> [    3.912898]         8fd51022 00000000 8ca86302 2f62696e 2f736800 00000000 00000010 8cb05e80
> [    3.913537]         808b0000 00000000 00000000 00040900 00000e51 00000000 7ffffe51 564ac4ac
> [    3.914176]         8ca86300 00000000 8cad8180 00040900 8cb02600 808b0000 00000044 00000044
> [    3.914904]         564ac4e4 8fd51000 8ca86300 00000000 8ca86300 80400a7c 564ac4ac 803005a0
> [    3.915595]         ...
> [    3.915786] Call Trace:
> [    3.915980] [<80741a78>] __schedule+0x62c/0xaa8
> starting version 232
> [   46.611678] random: systemd-udevd: uninitialized urandom read (16 bytes read)
> [   46.618684] random: systemd-udevd: uninitialized urandom read (16 bytes read)
> [   46.701579] random: udevadm: uninitialized urandom read (16 bytes read)
> Begin: Loading essential drivers ... done.
> Begin: Running /scripts/init-premount ... done.
> Begin: Mounting root file system ... Begin: Running /scripts/local-top ... done.
> Begin: Running /scripts/local-premount ... Begin: Waiting for suspend/resume device ... [    9.552903] INFO: rcu_sched self-detected stall on CPU
> [    9.553683] 1-...: (3 ticks this GP) idle=391/140000000000001/0 softirq=0/0 fqs=0
> [    9.554157] (t=10615 jiffies g=-290 c=-291 q=2422)
> [    9.554600] rcu_sched kthread starved for 10615 jiffies! g4294967006 c4294967005 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x1
> [    9.561916] rcu_sched       S    0     7      2 0x00100000
> [    9.562364] Stack : 81f642c0 8fca8280 8fcfc900 8fcfd1c0 8fcfc900 8fcffdf4 808b0000 8fcffdf4
> [    9.563023]         808b0000 8ca24400 81f6e680 808b0000 8fcffdf4 801c6ef8 8fcfc900 8fcffdf4
> [    9.563344]         81f6e680 808b0000 81f6e680 808b0000 00000000 ffffffff 00000001 80741f44
> [    9.563627]         8fcffdf4 809a0000 808b0000 fffeffd9 fffeffd9 807454f8 8fcffe98 808b0000
> [    9.563956]         808c2650 801921c4 00000001 81f6e680 00000001 00000000 81f6e748 fffeffd9
> [    9.564258]         ...
> [    9.564426] Call Trace:
> [    9.564997] [<80741a78>] __schedule+0x62c/0xaa8
> [    9.565428] [<80741f44>] schedule+0x50/0xf0
> [    9.565558] [<807454f8>] schedule_timeout+0x1ec/0x484
> [    9.565741] [<801c1580>] rcu_gp_kthread+0x5bc/0xa90
> [    9.565900] [<80161a74>] kthread+0xfc/0x114
> [    9.566035] [<80106a58>] ret_from_kernel_thread+0x14/0x1c
> [    9.566478] Task dump for CPU 0:
> [    9.566603] swapper/0       R  running task        0     0      0 0x00100000
> [    9.566828] Stack : 00000008 801e1874 808c21e4 81f5f618 808c2734 00000000 00000000 00000000
> [    9.567327]         00000002 ffffffe3 81f5d200 00000000 00000008 081b3200 00000008 c71dc863
> [    9.567862]         7fffffff ffffffff 80812ae8 00040900 808b0804 00000001 808b0000 80920000
> [    9.568331]         80812ae8 80920000 00000001 00000000 00000000 801e1c58 808b0804 00000001
> [    9.568751]         808b0000 80920000 808b0804 80192c4c 808b0000 80742390 00000000 00000000
> [    9.569239]         ...
> [    9.569351] Call Trace:
> [    9.569509] [<80741a78>] __schedule+0x62c/0xaa8
> [    9.569758] Task dump for CPU 1:
> [    9.575233] cat             R  running task        0    93     88 0x08110004
> [    9.575695] Stack : 80aa9410 00000000 80ab0000 801ac6b8 00000000 00000000 80ab0000 801ac6b8
> [    9.576222]         0000001d 00000006 00000006 8fcfc900 00000000 00000000 0000000a 00000000
> [    9.576822]         00000000 80aa9412 0000001d 80aa9878 808b0000 808c24c0 808b0000 808b0808
> [    9.577385]         00000140 808b0000 00000000 00000000 00000000 00000000 00000000 00000000
> [    9.577911]         00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> [    9.578434]         ...
> [    9.578574] Call Trace:
> [    9.578734] [<8010d8d0>] show_stack+0xa0/0xc4
> [    9.579025] [<8027c2e4>] rcu_dump_cpu_stacks+0xe8/0x128
> [    9.579491] [<801c274c>] rcu_check_callbacks+0x854/0xa20
> [    9.579936] [<801ca378>] update_process_times+0x4c/0x80
> [    9.580254] [<801e1928>] tick_sched_handle.isra.4+0x34/0x94
> [    9.580587] [<801e19f8>] tick_sched_timer+0x70/0xdc
> [    9.580944] [<801cb9b4>] __hrtimer_run_queues+0x144/0x3d8
> [    9.581275] [<801cc6cc>] hrtimer_interrupt+0x118/0x338
> [    9.581582] [<80112580>] c0_compare_interrupt+0x8c/0xe4
> [    9.582524] [<801aee0c>] __handle_irq_event_percpu+0x8c/0x2a0
> [    9.582939] [<801af078>] handle_irq_event_percpu+0x58/0xbc
> [    9.583705] [<801b4820>] handle_percpu_irq+0x98/0xc8
> [    9.584026] [<801ae100>] generic_handle_irq+0x50/0x6c
> [    9.584392] [<80747e48>] do_IRQ+0x28/0x34
> [    9.585228] [<804a3800>] plat_irq_dispatch+0x64/0xb8
> [    9.585544] [<80106f68>] except_vec_vi_end+0xb8/0xc4
> [    9.586059] [<80306d7c>] path_init+0xe4/0x3b8
> [    9.587379] [<8030ac24>] path_openat+0x94/0x111c
> [    9.587725] [<8030d114>] do_filp_open+0xf4/0x138
> [    9.588053] [<802f6fc8>] do_sys_open+0x1c0/0x27c
> [    9.589432] [<80117f98>] syscall_common+0x34/0x58
> [   52.550795] INFO: rcu_sched self-detected stall on CPU
> [   52.552049] 1-...: (7 ticks this GP) idle=391/140000000000002/0 softirq=0/0 fqs=0
> [   52.552508] (t=32101 jiffies g=-290 c=-291 q=2422)
> [   10.105092] rcu_sched kthread starved for 32101 jiffies! g4294967006 c4294967005 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0
> [   12.124160] INFO: rcu_sched detected stalls on CPUs/tasks:
> [   13.123363] 1-...: (7 ticks this GP) idle=391/140000000000002/0 softirq=0/0 fqs=0
> [   15.121749] (detected by 0, t=32101 jiffies, g=-290, c=-291, q=2422)
> [   16.120913] Task dump for CPU 1:
> [   17.130901] cat             R  running task    [   19.129399] rcu_sched       R
> [   20.128479]   running task        0     7      2 0x00100000
> Stack :
> [   23.126117]  81f642c0 8fca8280 8fcfc900 8fcfd1c0 8fcfc900 8fcffdf4 808b0000 8fcffdf4qemu-system-mips: terminating on signal 15 from pid 3927
> ubuntu@ip-10-1-3-178:~/mipseb$
>
>
> On Sat, Oct 6, 2018 at 10:18 AM Jun Sun <[email protected]> wrote:
>>
>> After I added "-cpu 34Kf", qemu would start normally again even with "-smp 2" option.
>>
>> However, "cat /proc/cpuinfo" only shows 1 CPU.  "uname -a" shows the following which seems to suggest the kernel is not SMP aware.  Is there a kernel for malta with SMP support?
>>
>> Linux debian-mips 4.9.0-7-4kc-malta #1 Debian 4.9.110-3+deb9u2 (2018-08-13) mips GNU/Linux
>>
>> Thanks.
>>
>> Jun
>>
>> On Sat, Oct 6, 2018 at 8:47 AM Jun Sun <[email protected]> wrote:
>>>
>>> Hi, all,
>>>
>>> I've been loosely following the instruct at this page, https://github.com/kholia/mips-hacking
>>>
>>> My host is ubuntu 16.04.  I used ubuntu prebuilt qemu system images.
>>>
>>> My guest is the latest stretch 9.5 malta netboot images.  Kernel is vmlinux-4.9.0-7-4kc-malta.
>>>
>>> Below is my startup script.  If I change "smp" to 2, the startup will hang very early on.   Does anybody if this is a known limit with debian distro?  Or it is an issue with the ubuntu prebuilt qemu?  Or there are some other gotcha's here?
>>>
>>> qemu-system-mips \
>>> -M malta \
>>> -m 256 \
>>> -hda hda.qcow2 \
>>> -kernel vmlinux-4.9.0-7-4kc-malta \
>>> -initrd initrd.img-4.9.0-7-4kc-malta \
>>>     -append "root=/dev/sda1 console=ttyS0 nokaslr" \
>>> -nographic \
>>> -redir tcp:2222::22 \
>>> -smp 1 \
>>> \
>>>
>>> Cheers.
>>>
>>> Jun
>>>
>>>
>>>


-- 
YunQiang Su