Hi Maryam,

The code that you are looking at is going to change soon. There is a changeset 
on the google reviewboard which will add some fidelity to the tracing of 
mmap/munmaps from the perspective of SE mode 
(https://gem5-review.googlesource.com/c/public/gem5/+/12307). Feel free to 
review it if it's interesting to you.

1) I don't understand what you are asking.
2) The new patch has an implementation.
3) We could probably add an implementation that flushes file-backed mmaps to 
the host file. I have never run into a situation where this was needed in an 
application that was being simulated (so it doesn't have an implementation).
4) It turns out that fork is not used in Linux to create a new process. It uses 
the clone system call instead. (You can verify this by using the Linux strace 
command with your application. You should only see a clone call.) You should 
take a look at the clone implementation.

Regards,
Brandon

-----Original Message-----
From: gem5-dev <[email protected]> On Behalf Of Maryam Babaie
Sent: Friday, March 8, 2019 4:06 PM
To: [email protected]
Subject: [gem5-dev] Syscall_Emulation for Shared Memory

Hi all,
I have some questions regarding the system calls available in SE mode on
gem5 for X86. I appreciate if any one shares their insight about them:

1. For the mmap syscall, the function "mmapImpl" has been implemented.
Up-to which extend this function will work properly for mmap syscall?

2. For munmap syscall, they have put the munmapFunc, but the body of the 
corresponding function is actually empty. So, does this mean it is actually not 
supported on gem5?

3. msync syscall is flagged as unimplementedFunc. So, does this mean that mmap 
will still work but the writes will not be reflected persistently in the region?

4. Since the fork syscall is also flagged as unimplementedFunc , how is the 
concept of Copy on Write (generally shared pages) able to be simulated and 
handled in gem5?

Regards
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