Re: [Gems-users] physical_address 0

["Dave Z." <zhu_dave@xxxxxxxxx>]

This is under Solaris 10. The machine I'm using is sarek (simics 2.2.19). s.physical_address is always 0 in ruby_operate, SimicsDriver, and SimicsProcessor when trying to access the memory mapped area.

The memory address space is 4G in Ruby and Simics. The kernel memory I'm allocating is one page (8K), but I'm mmapping only 1K.

All the accesses to the memory mapped region (no matter what the offset is) point to 0. I've asked on the simics forum, but they couldn't reproduce the same problem. I don't understand... Thanks for your help.

Dave

----- Original Message ----
From: Philip Garcia <pcgarcia@xxxxxxxx>
To: Gems Users <gems-users@xxxxxxxxxxx>
Sent: Saturday, January 20, 2007 10:12:07 AM
Subject: Re: [Gems-users] physical_address 0

Is this under solaris or linux?  Also, is this followed by a trap to the tlb miss handler?  How big is the memory address space?  Actually, if the mmap for address 0xfffa000 pointed to 0x0 then accessing 0xfffa00a should goto address 0xa.  If this isn't the case, something isn't working right (although I've never used the memop operator myself.   I'd ask on the simics.net forum if anyone has seen this problem, might be some weird simics thing.

phil

On Jan 20, 2007, at 11:18 AM, Dave Z. wrote:

Yes, Simics is actually passing Ruby a physical address of 0. I have some kernel memory mmap'ed into my application. "ptr" points to the mmap'ed memory space, and I know the logical address of ptr. When I do ptr[offset] = value or value = ptr[offset], the physical addresses for the memory requests are always 0.

Thanks,
Dave

----- Original Message ----
From: Dan Gibson <degibson@xxxxxxxx>
To: Gems Users <gems-users@xxxxxxxxxxx>
Sent: Friday, January 19, 2007 2:35:14 PM
Subject: Re: [Gems-users] physical_address 0

I thought you were calling SIM_logical_to_physical to determine the physical address. Do you mean that Simics is actually passing Ruby a physical address of zero? If so, what is the ASI, and what type of access (eg store, atomic, etc.) is it?

Regards,
Dan

Dave Z. wrote:

But there is no SIM_logical_to_physical in SimicsProcessor::makeRequest. If I understand correctly, the order of function calls is ruby_operate (ruby.c), _possible_cache_miss (commands.C), makeRequest (SimicsDriver.C), makeRequest (SimicsProcessor.C). The physical address is always 0 for certain logical addresses.

Thanks,
Dave

----- Original Message ----
From: Dan Gibson <degibson@xxxxxxxx>
To: Gems Users <gems-users@xxxxxxxxxxx>
Sent: Thursday, January 18, 2007 8:16:58 PM
Subject: Re: [Gems-users] physical_address 0

You might want to check
 that SIM_logical_to_physical isn't raising any 
exceptions. Have a look at SIM_last_exception().

Regards,
Dan

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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