Machine check exception. 2.6.20 powerpc tree.

[Kumar Gala]

On Jul 17, 2007, at 9:21 AM, Ramirez-Ortiz, Jorge wrote:

> Running our multithreaded application on ppc8548 (E500 core)  
> generates a machine check exception when trying to access some  
> ASIC’s registers mapped on the PCI space (This application maps a  
> PCI device to access its registers)
>
>
>
> machine_check_exception: task my_process, MCSR=0x10008, NIP=0x10153530
>
> Machine check in user mode.
>
> Caused by (from MCSR=10008): Guarded Load or Cache-Inhibited stwcx.
>
> Bus - Read Data Bus Error
>
>
>
> Here is the assembly dump of the region of code containing the  
> offending instruction in user-space, with SRR0 pointing us at  
> 0x10153530 when the exception is raised:
>
>
>
> 0x10153528 <_ZN2vk7in_le32EPVKj+16>:    lwz     r0,8(r31)
>
> 0x1015352c <_ZN2vk7in_le32EPVKj+20>:    lwz     r9,8(r31)
>
> 0x10153530 <_ZN2vk7in_le32EPVKj+24>:    lwbrx   r0,0,r0
>
> 0x10153534 <_ZN2vk7in_le32EPVKj+28>:    twi     0,r0,0
>
> 0x10153538 <_ZN2vk7in_le32EPVKj+32>:    isync

Can you get the code to dump the value of r0.  I'm wondering if  
you're really getting a read data bus error due to the fact that r0  
is pointing to a PCI address that doesn't have a device that will  
respond.

- k