[gem5-users] Re: Reading from memory in Gem5

[ABD ALRHMAN ABO ALKHEEL via gem5-users]

Ok. Thank you very much for your email.

________________________________
From: Jason Lowe-Power <ja...@lowepower.com>
Sent: Tuesday, August 4, 2020 4:41 PM
To: ABD ALRHMAN ABO ALKHEEL <abdkeel...@hotmail.com>; gem5 users mailing list 
<gem5-users@gem5.org>
Subject: Re: [gem5-users] Re: Reading from memory in Gem5

Hello,

First of all, please reply to the users list, not directly to the person who 
responded. This allows everyone to see answers and/or chime in and help.

Second, the page you linked is out of date. Please use the main gem5 website 
for all of the up to date documentation (e.g., 
http://doxygen.gem5.org/release/current/classLSQUnit.html)

Third, I still don't fully understand what your goals are. However, you can use 
the system port (actually, I think I was wrong before, you should use the 
"getPort" function, not "getSystemPort") to make functional (or debug) accesses 
to the memory. You can create a `Packet` with a `Request` and send a functional 
request across the port (i.e., call sendFunctional(pkt)). You can use either 
virtual (in SE mode) or physical address (in both modes). I am sure there are 
some caveats to using virtual addresses, but I don't know exactly what they are.

If you're trying to make new timing accesses, then you should use the main 
"dcache_port" and "icache_port" that are connected to the CPU. Again, you can 
construct a Packet object with a Request and send it across the port (e.g., 
sendTimingReq(pkt)).

You may want to read up on the details of how gem5's memory objects work: 
http://www.gem5.org/documentation/learning_gem5/part2/memoryobject/

Cheers,
Jason



On Mon, Aug 3, 2020 at 1:15 PM ABD ALRHMAN ABO ALKHEEL 
<abdkeel...@hotmail.com<mailto:abdkeel...@hotmail.com>> wrote:
Hi Jason,

Thanks for your email.

What I want to do is finding the memory address that the LD instruction loads 
data from ( I can get the physical and virtual address from the Read method in 
the lsqunit)http://pages.cs.wisc.edu/~swilson/gem5-docs/classLSQUnit.html and 
saving those addresses. After a specific time, I want to access the memory to 
read the data from those addresses. Can I use getSystemPort function to access 
the memory and read the data from those addresses? If so, should I use the 
virtual address or the physical address?

Thanks


________________________________
From: Jason Lowe-Power <ja...@lowepower.com<mailto:ja...@lowepower.com>>
Sent: Monday, August 3, 2020 3:26 PM
To: gem5 users mailing list <gem5-users@gem5.org<mailto:gem5-users@gem5.org>>
Cc: gem5-users 
<gem5-users-boun...@gem5.org<mailto:gem5-users-boun...@gem5.org>>; ABD ALRHMAN 
ABO ALKHEEL <abdkeel...@hotmail.com<mailto:abdkeel...@hotmail.com>>
Subject: Re: [gem5-users] Re: Reading from memory in Gem5

Hello,

This sounds like you probably want to use "functional" accesses. These are 
built for introspection and debugging, which is what it sounds like you want to 
do. Using the System object, there is a `getSystemPort` function that will 
return a gem5 port that you can use with functional accesses to "backdoor" into 
the memory. See 
http://doxygen.gem5.org/release/current/classSystem.html#a5ecbd1eaa3e0d19f4640bb71a0b59d64.

Cheers,
Jason

On Sun, Aug 2, 2020 at 7:01 AM ABD ALRHMAN ABO ALKHEEL via gem5-users 
<gem5-users@gem5.org<mailto:gem5-users@gem5.org>> wrote:
Hi All, how to read data from memory in Gem5 ? Can I read data from memory in 
Gem5  for a specific addresses? If so, should I use the virtual address or 
physical address? For example, how load instructions read the data from memory? 
Any help would be appreciated. Thanks

________________________________
From: ABD ALRHMAN ABO ALKHEEL
Sent: Saturday, August 1, 2020 3:19 PM
To: gem5 users mailing list <gem5-users@gem5.org<mailto:gem5-users@gem5.org>>; 
gem5-users <gem5-users-boun...@gem5.org<mailto:gem5-users-boun...@gem5.org>>
Subject: Reading from memory in Gem5

Hi All, how to read data from memory in Gem5 ? Can I read data from memory in 
Gem5  for a specific addresses? If so, should I use the virtual address or 
physical address? For example, how load instructions read the data from memory? 
Any help would be appreciated. Thanks
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