Arshad, Farrukh wrote:
> Adding more it,
>
> I have removed the shared memory kernel driver dependency just to narrow down
> the problem area and I have written a small piece of code in user space. A
> writer & a reader application which access the shared memory and I got the
> same behavior as with the shared memory kernel driver. Interestingly, my user
> space application work fine on P1022DS but not on P1022RDK however both using
> the same CPU modules.
>
> When I write a simple string on shared memory from Core 1 it is read at Core
> 0 properly
> When I write a simple string on shared memory from Core 0 it is not read at
> Core 1.
>
Did you dump TLB entry to check page memory coherence attribute for a shared
memory as I mentioned previously? This should be consistent on both sides.
> With this test now I am sure the problem lies in the kernel itself. Any
> pointers to look for the troubled area ?
>
> My application code is (error checking and other code is omitted)
>
> #define SHM_BASE 0x1C000000
> #define SHM_SIZE 0x400000 // 4 MB of Shared Memory
> #define PAGE_SIZE (4*1024)
>
> fd = open(device, O_RDWR);
You may need to add with 'O_SYNC'.
Tiejun
>
> shm = malloc(SHM_SIZE + (PAGE_SIZE - 1));
> if ( (unsigned long) shm % PAGE_SIZE) {
> shm += PAGE_SIZE - ((unsigned long)shm % PAGE_SIZE);
> }
>
> shm = mmap(shm, SHM_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED | MAP_FIXED, fd,
> SHM_BASE);
> ......
> ...... write some string at shm.
>
> My memory partitioning for both systems is
>
> Core Base Address Size
> Core 0 0x0000,0000 0x1000,0000
> Core 1 0x1000,0000 0x0C00,0000
> Shared Memory 0x1C00,0000 0x0400,0000
>
> Regards,
> Farrukh Arshad.
> Mentor Graphics Pakistan
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