Re: [Gems-users] physical_address 0

[Philip Garcia <pcgarcia@xxxxxxxx>]

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I don't know how solaris does it, but I know I have observed in Linux  
that memory that has been allocated with malloc will translate to  
physical address 0 before that page has been written to.  The  
translation will be valid, however read only.   Upon a write to the  
logical memory address linux will perform a page fault and point the  
logical address to a valid physical page in memory.   This appears to  
be a trick on top of standard demand paging.  You might want to check  
if this still happens after the memory has been written to.
Phil
On Jan 18, 2007, at 6:37 PM, Dave Z. wrote:

> Hi,
>
> I have a quick question about mem_trans object in  
> SimicsProcessor::makeRequest. Is it something expected to have  
> mem_trans->s.physical_address=0? I've printed the physical  
> addresses of some logical addresses and they are all 0. Here is  
> what I do:
>  if (mem_trans->s.logical_address == XXX)
>     printf("logical address %x physical address %x\n", mem_trans- 
> >s.logical_address, mem_trans->s.physical_address);
> Thanks,
>
> Dave
>
>
>
>
>
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