Software FPU emulation

Software FPU emulation

[srinivas pulipati]

hi all,

i have ported linux-2.4.4 to my custmoboard based on mpc860.
i got the bash prompt succesfully.

but is is crashing sometimes and giving FPU emulation., sig:8.
sometimes working perfectly.

is it because of UPM programming problem or something else?

thanks
srinivas


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Re: Software FPU emulation

[Jerry Van Baren]

98% certainty it is a memory (UPM) problem.  You are probably randomly
misreading an instruction as 0xFFxxxxxx which is a floating point
instruction.  This causes a FP emulation trap.  If you look at where the
trap occurred (SPR register SRR0) and look at the actual memory location in
question with your debugger, you probably will not find a FP instruction in
memory, which means it was misread.

gvb


At 02:21 PM 2/21/2002 +0530, srinivas pulipati wrote:

>hi all,
>
>i have ported linux-2.4.4 to my custmoboard based on mpc860.
>i got the bash prompt succesfully.
>
>but is is crashing sometimes and giving FPU emulation., sig:8.
>sometimes working perfectly.
>
>is it because of UPM programming problem or something else?
>
>thanks
>srinivas
>
>


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Software FPU Emulation

[hu]

1)environment
Linux kernel 2.4.4-rthal5
ppcboot 1.1.5
MPC823 board

2)I'm running a device driver which read data from touchpanel, sometimes
I get message like that:
Oops: Kernel Mode Software FPU Emulation, sig: 8
NIP: C000BC0C XER: C000206F LR: C000BC0C SP: C019FF60 REGS: c019feb0 TRAP: 1000
MSR: 00009032
TASK = c019dff0[0] 'swapper' Last syscall: 120
......
Call backtrace
C000BC0C C0003EE4 C0003EFC C01BA750 C00021E4

3)I check in System.map
C000BC0C 	Schedule
C0003EE4 	Letext(idled)
C0003EFC	cpu_idle
C01BA750	start_kernel
C00021E4	start_here

4)I dont know how can I do, from messages above, I cant see any clue to solve.

John Hu
hl76@263.net

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Re: Software FPU Emulation

[Wolfgang Denk]

In message <20040729083532.57B4F2F7B5@smtp.263.net> you wrote:
>
> 1)environment
> Linux kernel 2.4.4-rthal5
> ppcboot 1.1.5
> MPC823 board

Alls these are pretty old versions. Did you  try  running  some  more
recent code?

> 2)I'm running a device driver which read data from touchpanel, sometimes
> I get message like that:
> Oops: Kernel Mode Software FPU Emulation, sig: 8

Maybe a bug in your driver?

Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
Monday is an awful way to spend one seventh of your life.

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