Problem in getting shared memory access on P1022RDK

[Arshad, Farrukh]

Some of the other things which I am experiencing which may help to trace this issue. 

1: For Core 0 printk is not working in setup_arch "just before call to paging_init", where as on Core 1 printk is working in the same function. I see the source uses ppc_md.progress to display debug messages so it seems printk will not work then why it is working on Core 1. 
2: During kernel boot of both cores boot messages of Core 0 are mixed in Core 1 messages. 
3: If I change memory partitioning to following, then on Core 1 when I mmap shared memory area (starting 0x0C00,0000) I receive error that can not mmap RAM. If my both systems memory partitions are defined clearly then this area does not belong to system RAM then I shouldn't receive this error in this memory partitioning.

Core		Base Address		Size
Core 0		0x0000,0000		0x0C00,0000	--> CONFIG_PHYSICAL_START = bootm_low = Base Address
Shared Mem	0x0C00,0000		0x0400,0000
Core 1		0x1000,0000		0x1000,0000	--> CONFIG_PHYSICAL_START = bootm_low = Base Address

I believe there is some bug / or patch which I am missing in both kernels memory initialization which is causing all these issues. Kernel sources / configuration of both cores are 100% same except (CONFIG_PHYSICAL_START) param and kernel version is 2.6.32.13. 

Any thoughts.

Regards,
Farrukh Arshad


-----Original Message-----
From: Arshad, Farrukh 
Sent: Wednesday, January 04, 2012 11:50 AM
To: 'Scott Wood'
Cc: linuxppc-dev at lists.ozlabs.org
Subject: RE: Problem in getting shared memory access on P1022RDK

How can I verify if the memory mapped is coherent on both cores. My memory partitioning is given below

Core		Base Address		Size
Core 0		0x0000,0000		0x1000,0000	--> CONFIG_PHYSICAL_START = bootm_low = Base Address
Core 1		0x1000,0000		0x0C00,0000	--> CONFIG_PHYSICAL_START = bootm_low = Base Address
Shared Mem	0x1C00,0000		0x0400,0000

Regards,
Farrukh Arshad

-----Original Message-----
From: Scott Wood [mailto:scottwood at freescale.com]
Sent: Tuesday, January 03, 2012 10:10 PM
To: Arshad, Farrukh
Cc: linuxppc-dev at lists.ozlabs.org
Subject: Re: Problem in getting shared memory access on P1022RDK

On 01/03/2012 03:42 AM, Arshad, Farrukh wrote:
> Adding more to it,
> 
>  
> 
> When I write from Core 1 on the shared memory region it is visible at 
> Core 0 and it can read what I have written from Core 1 but when I 
> write from Core 0 on this shared memory it is not visible on Core 1.

Is the memory mapped coherent on both cores?

-Scott