APU disabled after context switch in Xilkernel

- A
- Andreas Hofmann
  
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posted
17 years ago

Wed, Sep 20, 2006 2:10 PM

Hello,

i'm trying to move data between the ppc405-core of a V4FX20 and a microblaze. The ppc and the microblaze are connected via an FSL link:

PPC-APU FCB FCB2FSL FSL MB

To transfer data the putfsl()/getfsl() functions are used.

The data transfer works flawlessly if the standalone BSP is used on the PPC. If xilkernel is used on PPC and a task switch occurs between enabling the APU and calling putfsl()/getfsl() an unknown-instruction exception is generated. It looks like the MSR is not properly saved and/or restored. Is this the case or do i have to do a little more than just set bit 6 in MSR?

Regards, Andreas

- V
- Vasanth Asokan
  
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posted
17 years ago

Wed, Sep 20, 2006 6:12 PM

Are the fsl() functions being invoked in the same task (after a context switch) or in a different task?

If in a different task - are you enabling the MSR APU bits prior to the kernel being initialized? Global processor level initialization (such as MSR, caches and other core registers) should happen before xilkernel_main(). This will convey the user's intent regarding the processor state to the kernel and ensure that all subsequent task switches get the same MSR value.

Vasanth

- A
- Andreas Hofmann
  
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posted
17 years ago

Thu, Sep 21, 2006 10:12 AM

Vasanth Asokan schrieb:

Hi,

There are two task running: one who invokes the fsl() functions and one which just spends some CPU time to increment an int value. The latter task is not necessary, calling sleep() in the task invoking the fsl() functions leads to similar behaviour because of the context switch to the idle task.

Caches are disabled and APU is enabled in main() prior to invoking xilkernel_main(). The task invoking the fsl() functions is statically defined in the static_pthread_table.

This is the failing code:

//----------------------------------------------------------------------------- #include "xmk.h" #include "xparameters.h" #include "xbasic_types.h" #include "xcache_l.h" #include "xpseudo_asm.h" #include "stdio.h" #include "pthread.h"

void enable_APU() { Xuint32 msr_value = mfmsr(); msr_value |= XREG_MSR_APU_AVAILABLE; mtmsr(msr_value); }

void* busy() { int l = 0;

while( l < (2