Re: [Qemu-devel] qemu-system-arm system support for big endian BE8

[sridhar kulkarni]

Hi,

Floating point exception error was the result of a divide by zero in the application. That is now solved and I was able to progress pretty well with Big Endinan code.

Currently QEMU crashes during handling interrupt controller.

Following the dump that I captured.

----------------

IN:

0xe003b47c: 68e0 ldr r0, [r4, #12]

0xe003b47e: b110 cbz r0, 0xe003b486

Trace 0x7f1af25f8410 [e003b47c]

R00=00000001 R01=0001c200 R02=00000001 R03=c16890e8

R04=c16890e8 R05=e003b18c R06=00000080 R07=0000a000

R08=ffffffff R09=00000001 R10=0001c200 R11=00000000

R12=00000000 R13=c1c3a320 R14=e003b33d R15=e003b47c

PSR=20000133 --C- T svc32

----------------

IN:

0xe003b486: f8d4 b01c ldr.w fp, [r4, #28]

0xe003b48a: f44f 5180 mov.w r1, #4096 ; 0x1000

0xe003b48e: f241 1021 movw r0, #4385 ; 0x1121

0xe003b492: f8ab 1000 strh.w r1, [fp]

0xe003b496: f64f 4100 movw r1, #64512 ; 0xfc00

0xe003b49a: f2c7 4102 movt r1, #29698 ; 0x7402

0xe003b49e: 8008 strh r0, [r1, #0]

0xe003b4a0: f242 1012 movw r0, #8466 ; 0x2112

0xe003b4a4: 8048 strh----------------

IN:

0x00000194: e121f000 msr CPSR_c, r0

Trace 0x7f1af259c000 [00000194]

R00=8000039f R01=80000380 R02=770004c8 R03=80000380

R04=00000148 R05=00000000 R06=c16890e8 R07=00000001

R08=00000001 R09=00000000 R10=00000000 R11=c16746e1

R12=00000000 R13=00004b80 R14=00000188 R15=00000194

PSR=80000380 N--- A usr26

qemu: hardware error: bank number requested for bad CPSR mode value 0x0

CPU #0:

R00=8000039f R01=80000380 R02=770004c8 R03=80000380

R04=00000148 R05=00000000 R06=c16890e8 R07=00000001

R08=00000001 R09=00000000 R10=00000000 R11=c16746e1

R12=00000000 R13=00004b80 R14=00000188 R15=00000194

PSR=80000380 N--- A usr26

s00=00000000 s01=00000000 d00=0000000000000000

s02=00000000 s03=00000000 d01=0000000000000000

s04=00000000 s05=00000000 d02=0000000000000000

s06=00000000 s07=00000000 d03=0000000000000000

s08=00000000 s09=00000000 d04=0000000000000000

s12=00000000 s13=00000000 d06=0000000000000000

s14=00000000 s15=00000000 d07=0000000000000000

s16=00000000 s17=00000000 d08=0000000000000000

s18=00000000 s19=00000000 d09=0000000000000000

s20=00000000 s21=00000000 d10=0000000000000000

s22=00000000 s23=00000000 d11=0000000000000000

s24=00000000 s25=00000000 d12=0000000000000000

s26=00000000 s27=00000000 d13=0000000000000000

s28=00000000 s29=00000000 d14=0000000000000000

s30=00000000 s31=00000000 d15=0000000000000000

s32=00000000 s33=00000000 d16=0000000000000000

s34=00000000 s35=00000000 d17=0000000000000000

s36=00000000 s37=00000000 d18=0000000000000000

s38=00000000 s39=00000000 d19=0000000000000000

s40=00000000 s41=00000000 d20=0000000000000000

s42=00000000 s43=00000000 d21=0000000000000000

s44=00000000 s45=00000000 d22=0000000000000000

s46=00000000 s47=00000000 d23=0000000000000000

s48=00000000 s49=00000000 d24=0000000000000000

s50=00000000 s51=00000000 d25=0000000000000000

s52=00000000 s53=00000000 d26=0000000000000000

s54=00000000 s55=00000000 d27=0000000000000000

s56=00000000 s57=00000000 d28=0000000000000000

s58=00000000 s59=00000000 d29=0000000000000000

s60=00000000 s61=00000000 d30=0000000000000000

s62=00000000 s63=00000000 d31=0000000000000000

FPSCR: 03000000

Aborted (core dumped)

_______________________________________________________

Please let me know if you have inputs for this crash. Also let me know if you need any further info to help look in to this.

Regards

Sridhar

　

On Thursday, September 24, 2015 9:47 PM, Peter Crosthwaite <address@hidden> wrote:

On Thu, Sep 24, 2015 at 3:48 AM, sridhar kulkarni
<address@hidden> wrote:
> The issue is mostly related to my application under test. When the
> application calls a function the PC is getting set up to a wrong address,
> and then qemu crashes by displaying "floating point exception(core dumped)"
> message.
> I am able to move ahead by resolving the issue.

Was this a QEMU bug or an issue in your program?

But interestingly whenever
> my app crashes it always displays the same "floating point exception"
> message. But I don't see any floating operations at the point code crashes.
> I don't see any dump of the processor registers also. It's always just a one
> line message as I described above.
>

Ok, are you unable to share the binary or source? Alternatively, can
you strip it down to a super-minimal program that replicates just this
one issue? Pasting us a GDB backtrace of the failure might help as
well.

Regards,
Peter

> Regards
> Sridhar
>
>
>
> On Thursday, September 24, 2015 8:23 AM, Peter Crosthwaite
> <address@hidden> wrote:
>
>
> On Wed, Sep 23, 2015 at 8:41 AM, Peter Maydell <address@hidden>
> wrote:
>> On 23 September 2015 at 03:48, sridhar kulkarni <address@hidden>
>> wrote:
>>> Hi Peter,
>>>
>>> I was able to progress well using the BE8 work in the branch that you
>>> pointed out. I am experiencing floating point issue. The qemu just exits,
>>> by
>>> putting a message that "floating point exception(core dumped)". I suppose
>>> QEMU do support floating point operations. I heard about hard floating
>>> point
>>> and soft floating point support. Is there any configuration option in
>>> QEMU
>>> for floating point?
>>
>> QEMU's floating point support for ARM is good and known to work.
>> If QEMU exits with a coredump then that is either:
>>  * your test binary is dumping core due to a bug in your test
>>    (assuming you're using linux-user mode)
>>  * a bug in QEMU (unlikely but not impossible)
>>
>> If you can provide a reproducible test case we can have a look at it.
>>
>
> Yes, so the thing stopping me upstreaming this was a reasonable test.
> Can I have a look at your reproducer?
>
> Regards,
>
> Peter
>
>> thanks
>> -- PMM
>
>
>