[Xen-devel] Xen ARM and rtds real-time scheduler: local_irq_is_enabled() assert

[Leonardo Taccari <iamleot@xxxxxxxxx>]

Good afternoon to the entire Xen community!
In the previous months I have succesfully installed and run xen-4.4 on a
cubieboard2 (running Debian GNU/Linux testing armhf).

Now I am interested on trying and testing the rtds real-time scheduler
and so I have compiled xen-devel (master branch ~1-2 days ago) via an
armhf chroot generated via debootstrap[0] (Debian testing, the same
version of the one I have installed in the microsd of cubieboard2),
running everything through QEMU user mode emulation (dynamic binary
translation).
I have used this setup in order to compile xen toolstack on an amd64
machine (and thanks to the armhf chroot and QEMU user mode emulation I
avoided the cross-compilation).

I have applied the four patches regarding rtds real-time scheduler
appeared on xen-devel@ ML with the subject "[PATCH for 4.5 v4 [1-4]/4]"
(I've also needed to apply a patch that fixes a printf(3) syntax in
burn_budget() from Ian Campbell[1]).

I tried to reproduce the scenario described by Meng Xu.
Here it is the complete output on the cubieboard2 (connected via an USB
TTL UART), the problem regards local_irq_is_enabled() assertion is at the
end with the Xen stack trace and call trace:


[...]
root@cubieboard:~# /etc/init.d/xencommons start
Starting /usr/local/sbin/xenstored...
Setting domain 0 name, domid and JSON config...
Done setting up Dom0
Starting xenconsoled...
Starting QEMU as disk backend for dom0
/etc/init.d/xencommons: line 114: /usr/local/lib/xen/bin/qemu-system-i386: No
such file or directory
root@cubieboard:~# xl sched-rtds
root@cubieboard:~# xl sched-rtds -d Domain-0 -p 20000 -b 10000
libxl: error: libxl.c:5481:sched_rtds_domain_set: getting domain sched rtds:
Invalid argument libxl_domain_sched_params_set failed.
root@cubieboard:~# xl cpupool-list
Name               CPUs   Sched     Active   Domain count
Pool-0               2    credit       y          1
root@cubieboard:~# xl cpupool-cpu-remove Pool-0 1
root@cubieboard:~# xl cpupool-list
Name               CPUs   Sched     Active   Domain count
Pool-0               1    credit       y          1
root@cubieboard:~# xl cpupool-create name=\"rt\" sched=\"rtds\"
Using config file "command line"
cpupool name:   rt
scheduler:      rtds
number of cpus: 0
(XEN) Initializing RTDS scheduler
(XEN) WARNING: This is experimental software in development.
(XEN) Use at your own risk.
root@cubieboard:~# xl cpupool-cpu-add rt 1
root@cubieboard:~# cd xen/debian-testing
root@cubieboard:~/xen/debian-testing# losetup /dev/loop0 
/root/xen/debian-testing/debian-testing.img
root@cubieboard:~/xen/debian-testing# xl create -c debian-testing.cfg
root@cubieboard:~# xl list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0   128     2     r-----      14.3
debian-testing                               1   128     1     ------       6.5
root@cubieboard:~# xl cpupool-list
Name               CPUs   Sched     Active   Domain count
Pool-0               1    credit       y          2
rt                   1      rtds       y          0
root@cubieboard:~# xl cpupool-migrate debian-testing rt
(XEN) Assertion 'local_irq_is_enabled()' failed, line 137, file spinlock.c
root@cubieboard:~/xen/debian-testing# (XEN) Xen BUG at spinlock.c:137
(XEN) CPU1: Unexpected Trap: Undefined Instruction
(XEN) ----[ Xen-4.5-unstable  arm32  debug=y  Not tainted ]----
(XEN) CPU:    1
(XEN) PC:     0024b590 __bug+0x2c/0x44
(XEN) CPSR:   200f01da MODE:Hypervisor
(XEN)      R0: 0027b6d4 R1: 3fd11d80 R2: 00000000 R3: 00000000
(XEN)      R4: 00000089 R5: 00272664 R6: 002fe020 R7: 00000049
(XEN)      R8: 4002f9f8 R9: 4002fa78 R10:40038ec0 R11:47fefe3c R12:3fd11d80
(XEN) HYP: SP: 47fefe34 LR: 0024b590
(XEN) 
(XEN)   VTCR_EL2: 80003558
(XEN)  VTTBR_EL2: 000200007ff04000
(XEN) 
(XEN)  SCTLR_EL2: 30cd187f
(XEN)    HCR_EL2: 000000000038643f
(XEN)  TTBR0_EL2: 0000000076010000
(XEN) 
(XEN)    ESR_EL2: 00000000
(XEN)  HPFAR_EL2: 000000000001c810
(XEN)      HDFAR: c8800f00
(XEN)      HIFAR: 3ba1661c
(XEN) 
(XEN) Xen stack trace from sp=47fefe34:
(XEN)    00000000 47fefe4c 00231f1c 003002a8 47fdd000 47fefe7c 0022c2c4 47fdd000
(XEN)    4002fa78 40011000 47fdd000 40011000 9d305069 00000049 00000001 40012040
(XEN)    00000001 47fefe8c 0023082c 47fdd000 40011000 47fefe9c 00250758 47fdd000
(XEN)    40011000 47fefeac 00250e18 40011000 47fdd000 47feff14 0022d5a4 00000000
(XEN)    002650bc 00000000 4002fa78 000f4240 00000000 47fefef8 00301594 00300324
(XEN)    00000000 47fdd000 00000000 000f4240 00000000 00000000 00000000 47fefef8
(XEN)    002c9ff4 00000001 00301594 002c6000 00000000 0027bb80 7fc00000 47feff34
(XEN)    002310c8 00301594 00301594 00300324 00000000 00000000 7fe00000 47feff3c
(XEN)    00231190 47feff54 00250ce0 00000001 00000000 10011142 00000000 47feff3c
(XEN)    0025d6c0 00000000 00000000 00000000 00000000 00000000 00000000 00000000
(XEN)    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
(XEN)    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
(XEN)    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
(XEN)    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
(XEN)    00000000 00000000 00000000
(XEN) Xen call trace:
(XEN)    [<0024b590>] __bug+0x2c/0x44 (PC)
(XEN)    [<0024b590>] __bug+0x2c/0x44 (LR)
(XEN)    [<00231f1c>] _spin_lock_irq+0x4c/0xdc
(XEN)    [<0022c2c4>] rt_context_saved+0x54/0x1d0
(XEN)    [<0023082c>] context_saved+0x7c/0xa4
(XEN)    [<00250758>] schedule_tail+0x150/0x31c
(XEN)    [<00250e18>] context_switch+0x114/0x128
(XEN)    [<0022d5a4>] schedule+0x8e4/0x940
(XEN)    [<002310c8>] __do_softirq+0xf8/0x118
(XEN)    [<00231190>] do_softirq+0x18/0x28
(XEN)    [<00250ce0>] idle_loop+0x1a4/0x1c8
(XEN)    [<0025d6c0>] start_secondary+0x1a0/0x1bc
(XEN) 
(XEN) 
(XEN) ****************************************
(XEN) Panic on CPU 1:
(XEN) CPU1: Unexpected Trap: Undefined Instruction
(XEN) 
(XEN) ****************************************
(XEN) 
(XEN) Reboot in five seconds...
[...]


 [0]: https://wiki.debian.org/Debootstrap
 [1]: http://lists.xen.org/archives/html/xen-devel/2014-09/msg03352.html


Thank you very much for your attention!
Ciao,
L.

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