Re: [Qemu-devel] [PATCH v2] ppc / sparc: Add a tester for checking whether OpenBIOS runs successfully

[Artyom Tarasenko]

On Fri, Jun 17, 2016 at 2:44 PM, Mark Cave-Ayland
<address@hidden> wrote:
> On 17/06/16 12:36, Artyom Tarasenko wrote:
>
>> Hi Mark,
>>
>> On Fri, Jun 17, 2016 at 1:27 PM, Mark Cave-Ayland
>> <address@hidden> wrote:
>>> On 17/06/16 07:07, David Gibson wrote:
>>>
>>>> On Wed, Jun 15, 2016 at 01:10:18PM +1000, David Gibson wrote:
>>>>> On Tue, Jun 14, 2016 at 03:57:56PM +0200, Thomas Huth wrote:
>>>>>> Since the mac99 and g3beige PowerPC machines recently broke without
>>>>>> being noticed, it would be good to have a tester for "make check"
>>>>>> that detects such issues immediately. A simple way to test the firmware
>>>>>> of these machines is to use the "-prom-env" parameter of QEMU. This
>>>>>> parameter can be used to put some Forth code into the 'boot-command'
>>>>>> firmware variable which then can signal success to the tester by
>>>>>> writing a magic value to a known memory location. And since some of the
>>>>>> Sparc machines are also using OpenBIOS, they are now tested with this
>>>>>> prom-env-tester, too.
>>>>>>
>>>>>> Reviewed-by: Markus Armbruster <address@hidden>
>>>>>> Signed-off-by: Thomas Huth <address@hidden>
>>>>>> ---
>>>>>>  v2: Removed unnecessary include statements (as suggested by Markus)
>>>>>
>>>>> Beautiful, I've applied this to ppc-for-2.7, assuming I don't get an
>>>>> objection to taking this through my tree.
>>>>
>>>> Ugh.. turns out this fails on sparc64 target on a 32-bit x86 host.
>>>> Specifically it trips the tcg_abort() at the end of tcg_reg_alloc()
>>>> (tcg/tcg.c).
>>>>
>>>> I'm reasonably confident this is a pre-existing bug, just triggered by
>>>> this test, but in the interests of getting this up and running on the
>>>> platforms where it is working, I've disabled the testcase on sparc64
>>>> for now.
>>>>
>>>> Mark, if you could debug the sparc64-on-i386 failure at some point,
>>>> that would be helpful.
>>>
>>> I'm a little tied up until next week, however I was able to reproduce on
>>> a local i386 VM and get a stack trace:
>>>
>>>
>>> $ gdb --args ./qemu-system-sparc64 -nographic
>>> GNU gdb (Debian 7.10-1.1) 7.10
>>> Copyright (C) 2015 Free Software Foundation, Inc.
>>> License GPLv3+: GNU GPL version 3 or later
>>> <http://gnu.org/licenses/gpl.html>
>>> This is free software: you are free to change and redistribute it.
>>> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
>>> and "show warranty" for details.
>>> This GDB was configured as "i686-linux-gnu".
>>> Type "show configuration" for configuration details.
>>> For bug reporting instructions, please see:
>>> <http://www.gnu.org/software/gdb/bugs/>.
>>> Find the GDB manual and other documentation resources online at:
>>> <http://www.gnu.org/software/gdb/documentation/>.
>>> For help, type "help".
>>> Type "apropos word" to search for commands related to "word"...
>>> Reading symbols from ./qemu-system-sparc64...done.
>>> (gdb) r
>>> Starting program: /home/build/rel-qemu-git/bin/qemu-system-sparc64
>>> -nographic
>>> [Thread debugging using libthread_db enabled]
>>> Using host libthread_db library "/lib/i386-linux-gnu/libthread_db.so.1".
>>> [New Thread 0xb7989b40 (LWP 27497)]
>>> [New Thread 0xb4af1b40 (LWP 27498)]
>>> OpenBIOS for Sparc64
>>> Configuration device id QEMU version 1 machine id 0
>>> kernel cmdline
>>> CPUs: 1 x SUNW,UltraSPARC-IIi
>>> UUID: 00000000-0000-0000-0000-000000000000
>>> /home/build/src/qemu/tcg/tcg.c:1743: tcg fatal error
>>>
>>> Program received signal SIGABRT, Aborted.
>>> [Switching to Thread 0xb4af1b40 (LWP 27498)]
>>> 0xb7fdadad in __kernel_vsyscall ()
>>> (gdb) bt
>>> #0  0xb7fdadad in __kernel_vsyscall ()
>>> #1  0xb7a2ee26 in __GI_raise (sig=6) at
>>> ../sysdeps/unix/sysv/linux/raise.c:55
>>> #2  0xb7a303f7 in __GI_abort () at abort.c:89
>>> #3  0x08061776 in tcg_reg_alloc (s=0x8637780 <tcg_ctx>,
>>> desired_regs=255, allocated_regs=255, rev=true) at
>>> /home/build/src/qemu/tcg/tcg.c:1743
>>> #4  0x0806181a in temp_load (s=0x8637780 <tcg_ctx>, ts=0x8637978
>>> <tcg_ctx+504>, desired_regs=255, allocated_regs=255) at
>>> /home/build/src/qemu/tcg/tcg.c:1762
>>> #5  0x080615e0 in tcg_reg_sync (s=0x8637780 <tcg_ctx>, reg=TCG_REG_EAX,
>>> allocated_regs=255) at /home/build/src/qemu/tcg/tcg.c:1694
>>> #6  0x08061653 in tcg_reg_free (s=0x8637780 <tcg_ctx>, reg=TCG_REG_EAX,
>>> allocated_regs=254) at /home/build/src/qemu/tcg/tcg.c:1709
>>> #7  0x08061740 in tcg_reg_alloc (s=0x8637780 <tcg_ctx>,
>>> desired_regs=255, allocated_regs=254, rev=true) at
>>> /home/build/src/qemu/tcg/tcg.c:1738
>>> #8  0x0806181a in temp_load (s=0x8637780 <tcg_ctx>, ts=0x8637978
>>> <tcg_ctx+504>, desired_regs=255, allocated_regs=254) at
>>> /home/build/src/qemu/tcg/tcg.c:1762
>>> #9  0x080615e0 in tcg_reg_sync (s=0x8637780 <tcg_ctx>, reg=TCG_REG_ECX,
>>> allocated_regs=254) at /home/build/src/qemu/tcg/tcg.c:1694
>>> #10 0x08061653 in tcg_reg_free (s=0x8637780 <tcg_ctx>, reg=TCG_REG_ECX,
>>> allocated_regs=252) at /home/build/src/qemu/tcg/tcg.c:1709
>>> #11 0x08061740 in tcg_reg_alloc (s=0x8637780 <tcg_ctx>,
>>> desired_regs=255, allocated_regs=252, rev=true) at
>>> /home/build/src/qemu/tcg/tcg.c:1738
>>> #12 0x0806181a in temp_load (s=0x8637780 <tcg_ctx>, ts=0x8637978
>>> <tcg_ctx+504>, desired_regs=255, allocated_regs=252) at
>>> /home/build/src/qemu/tcg/tcg.c:1762
>>> #13 0x08061858 in temp_load (s=0x8637780 <tcg_ctx>, ts=0x8637f48
>>> <tcg_ctx+1992>, desired_regs=255, allocated_regs=252) at
>>> /home/build/src/qemu/tcg/tcg.c:1765
>>> #14 0x0806220f in tcg_reg_alloc_op (s=0x8637780 <tcg_ctx>, def=0x859c150
>>> <tcg_op_defs+720>, opc=INDEX_op_sub2_i32, args=0x863be54
>>> <tcg_ctx+18132>, dead_args=60, sync_args=0 '\000') at
>>> /home/build/src/qemu/tcg/tcg.c:2050
>>> #15 0x08063156 in tcg_gen_code (s=0x8637780 <tcg_ctx>, tb=0xb4b14d90) at
>>> /home/build/src/qemu/tcg/tcg.c:2454
>>> #16 0x08058cb4 in tb_gen_code (cpu=0x8a9e370, pc=4291901680,
>>> cs_base=4291901684, flags=7, cflags=0) at
>>> /home/build/src/qemu/translate-all.c:1212
>>> #17 0x0805a8c5 in tb_find_slow (cpu=0x8a9e370, pc=4291901680,
>>> cs_base=4291901684, flags=7) at /home/build/src/qemu/cpu-exec.c:310
>>> #18 0x0805aa1e in tb_find_fast (cpu=0x8a9e370, last_tb=0xb4af1044,
>>> tb_exit=1) at /home/build/src/qemu/cpu-exec.c:339
>>> #19 0x0805b189 in cpu_sparc_exec (cpu=0x8a9e370) at
>>> /home/build/src/qemu/cpu-exec.c:625
>>> #20 0x0808666d in tcg_cpu_exec (cpu=0x8a9e370) at
>>> /home/build/src/qemu/cpus.c:1541
>>> #21 0x0808675b in tcg_exec_all () at /home/build/src/qemu/cpus.c:1574
>>> #22 0x08085c29 in qemu_tcg_cpu_thread_fn (arg=0x8a9e370) at
>>> /home/build/src/qemu/cpus.c:1171
>>> #23 0xb7bc12de in start_thread (arg=0xb4af1b40) at pthread_create.c:334
>>> #24 0xb7aeb23e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:122
>>> (gdb)
>>>
>>>
>>> I've added Richard as CC since it looks like this is something in the
>>> TCG core.
>>
>> While you are at it, can you please check, whether  -singlestep option
>> chanes anything at all?
>> It may help to see if the bug has to do with the TCG optimizer.
>
> Adding -singlestep seems to cause OpenBIOS to hang after displaying the
> initial banner here. Is this similar to -icount which is currently not
> working under SPARC64?

Yes, it is similar, but unlike -icount it is working. It slows down
things quite a bit, but on a x86_64 host I get:

CPUs: 1 x SUNW,UltraSPARC-IIi
UUID: 00000000-0000-0000-0000-000000000000
Welcome to OpenBIOS v1.1 built on Apr 18 2016 08:20
  Type 'help' for detailed information
Trying disk:a...
No valid state has been set by load or init-program
0 >   ok

It takes ~20 seconds to get there though.


-- 
Regards,
Artyom Tarasenko

SPARC and PPC PReP under qemu blog: http://tyom.blogspot.com/search/label/qemu