Infinite loop in PSOS_INIT()

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View

Problem Summary:
While executing the BSP code for our target board (on ARMulator, an
ARM instruction set simulator) the processor goes into an infinite
loop at PSOS_INIT(). We have no clue as to why this happens. Please
read below for more details. Thank-you!

We are using ARMulator to simulate a system that has an ARM946ES
processor, a UART connected to a Keyboard, an Interrupt Controller,
and a Timer, apart from other components. The UART, Keyboard,
Interrupt Controller and Timer are simulated as ARMulator extensions,
and other components are not simulated. PSOS is used in the real
hardware system. We compiled the code (for the real hardware system)
as a .axf image, loaded the image in ARM Extended Debugger (AXD), and
executed the code. We found that the processor went into an infinite
loop, in the function PSOS_INIT() (called from the function SysInit in
the file Sysinit.c of PSOS BSP).

This is the register dump, when ARMulator is in the infinite loop:
Registers Bank: Current (SVC mode)
Index Name Value
#1    r0   0x00000F0D
#2    r1   0x00000F0D
#3    r2   0x00000F0D
#4    r3   0x00000F0D
#5    r4   0x00000F0D
#6    r5   0x00000001
#7    r6   0x00000000
#8    r7   0x00000000
#9    r8   0x60000093
#10   r9   0x405233E0
#11   r10  0x60000093
#12   r11  0x00000000
#13   r12  0x00002000
#14   r13  0x40525068
#15   r14  0x0027CD18
#16   pc   0x0027B2F4
#17   cpsr 0x60000093
#18   spsr 0x00000000

This is the snapshot of ARMulator disassembly:
0027b2e4    [0xeafffffd]   b        0x27b2e0  ; (pSOS_Ienter + 0x930)
0027b2e8    [0xe10fa000]   mrs      r10,cpsr
0027b2ec    [0xe38a8080]   orr      r8,r10,#0x80
0027b2f0    [0xe129f008]   msr      cpsr_cf,r8
0027b2f4    [0xe1a00000]   nop               ;;;;}}} Infinite
0027b2f8    [0xeafffffd]   b        0x27b2f4 ;;;;}}} Loop
0027b2fc    [0xe8bd00f0]   ldmfd    r13!,

If someone can help us in identifying the cause of the problem, and
overcoming this, it will be of great help. Also, it will be extremely
useful, if someone lists various possible scenarios/exceptional
conditions under which PSOS_INIT drives the CPU to an infinite loop.
In our case, it goes into an unconditional infinite loop.

Thank you for your time.


Re: Infinite loop in PSOS_INIT()
Quoted text here. Click to load it

The loop you are in looks very much as if it might be the pSOS idle task. If
your own tasks are not running, for whatever reason, this would be where you
would end up; it's normal! I suggest that you look to see that your tasks
are properly formed (with infinite loops, so they never return) and properly

Also, as you seem to be working on a BSP, it's worth checking whether you
have actually put any of your own tasks into the system, yet!

Another thought...
Doesn't pSOS need a "start" call as well as an "init" call? (I can't
remember; it's been a while since I used it). If you don't make that call,
there might be some way for your initialisation code to run straight into
the idle task.

Peter Bushell /

Re: Infinite loop in PSOS_INIT()

Quoted text here. Click to load it

I'm not familiar with pSOS, but aren't the instructions at 2e8 to
2f4 in the listing above DISabling interrupts? In that case, this
seems to be some fatal error handling routine -- something is
catastrophically wrong, so disable interrupts and hang, to
force a reset (if there is a watchdog) or at least prevent
startup to an unsafe state.

I'm too lazy to look up what bit 7 of cpsr actually does, so I
might be totally out to lunch, in which case just ignore me.

Re: Infinite loop in PSOS_INIT()
Quoted text here. Click to load it

Apologies! Vic is quite right. I, too, was lazy and didn't check the code
properly. So ignore my previous post. Sorry I couldn't help.

Peter Bushell /

Re: Infinite loop in PSOS_INIT()

Quoted text here. Click to load it
Quoted text here. Click to load it

There is only one place in psos for ARM with a similar code sequence.

;* halt:   halt the processor                                           *
;* INPUTS:    NONE                                                      *
;* OUTPUTS:   NONE                                                      *
        Function halt
        MRS     r10, cpsr
        LDR     r8, [k_data, #kd_intrmask]
        ORR     r8, r10, r8
        MSR     cpsr_cf, r8
        NOP             ; This NOP is necessary to allow halt
                        ; to be single stepped.
        B       %BT0

Looks like halt, or some variation has been called.

Re: Infinite loop in PSOS_INIT()
IIRC, when pSOS has a configuration error it first attempts to do a
divide by zero operation, then it just loops if there is no DivByZero

My GUESS would be that you have something misconfigured.  Can you verify
that pSOS has already started correctly?  Note also that pSOS early in
its startup checksums itself, so you cannot have (software) breakpoints
set in the pSOS code itself during this time.  And depending on how
stepping is implemented on ARMulator, that may mess up the checksum too.
  Failing checksum is a sure way to get pSOS to go into its KFATAL call
(DivByZero and/or infinite loop).

spammers wrote:
Quoted text here. Click to load it

Site Timeline