Hi Abdul,

This touches on a pretty fundamental issue. The external port works fine for 
connecting devices, but when connecting a memory, there are a number of 
assumptions in gem5 that will give us problems. You have run into the first one 
which is that gem5 needs to be aware of the memory to report it to the OS. The 
external memory would thus have to be a subclass of AbstractMemory. Similarly, 
gem5 assumes that you can get a pointer into the actual backing store for the 
memory. This is used by functional accesses (only Alpha and X86 afaik) while 
the system is running. It is also used to support switching to/from KVM. I am 
not sure how to solve this. Again, if you subclass the AbstractMemory for your 
exernal memory, this should be ok.

Ultimately I think the best way forward is to create an ExternalMemory wrapper, 
similar to ExternalSlave, but also exposing the underlying memory and address 
ranges.

Andreas

From: gem5-users 
<[email protected]<mailto:[email protected]>> on behalf of 
Abdul Mutaal <[email protected]<mailto:[email protected]>>
Reply-To: gem5 users mailing list 
<[email protected]<mailto:[email protected]>>
Date: Monday, 3 August 2015 13:41
To: "[email protected]<mailto:[email protected]>" 
<[email protected]<mailto:[email protected]>>
Subject: [gem5-users] Gem5 ATAG error

Dear Community,

I am facing an error in full system simulation regarding  ATAG. The exact error 
is

fatal: Expected a single ATAG memory entry but got 0
 @ tick 0

The scenario is that I am booting ICS image on gem5 with external memory (don't 
want to use dram). As far I understood the system.cc doesn't find the range of 
physcial memory.

Is that true? are there any other reasons for this error?

Also I run the same configuration with memory controller with SimpleMemory. It 
works fine.

Thanks

--

Regards,
Abdul Mutaal



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