Frequently Asked Questions
From gem5
- How can I see the packets on the ethernet link?
- By creating a Etherdump object, setting it's file parameter, and setting the dump parameter on the EtherLink to it. This is most easily accomplished by setting the enivornment variable
-EDUMPFILE=<file>. The resulting file will be named<file>and be in a standard pcap format.
- By creating a Etherdump object, setting it's file parameter, and setting the dump parameter on the EtherLink to it. This is most easily accomplished by setting the enivornment variable
- How do I create a disk image?
- You can use the
mkblankimage.shscript that is provided in our distribution of linux-dist to create a blank image of arbitrary size.
- You can use the
- How do I add files to a disk image?
- Using either sudo or the root account run
/bin/mount -o loop,offset=32256 /z/foo.img /mount/point. You can then copy the desired files to the image. Remember to unmount it before running the simulator with/bin/umount /mount/pointor you may get unexpected results.
- Using either sudo or the root account run
- How do I access reference counted pointers in GDB?
- Objects such as DynInsts are reference counted, making it slightly harder to obtain the data inside. In gdb you must access them through the pointer that is stored in the ref counted pointer, which is called data. Thus given a ref counted pointer
ptr, in gdb you would say(gdb) ptr->datato get the pointer to the actual object.
- Objects such as DynInsts are reference counted, making it slightly harder to obtain the data inside. In gdb you must access them through the pointer that is stored in the ref counted pointer, which is called data. Thus given a ref counted pointer
- How do I build a cross compiler?
- Download cross-tool here. It is a script to simplify the creation of cross-compilers.
- How many CPUs can M5 run?
- There is no strict limit however the Alpha platform we support (Tsunami) only has support for 4 processors. We made some additions to the platform both in the simulator and in Linux to support up to 64 processors. However simulating 64 processors will be quite slow, and the Linux scheduler doesn't seem particularly good at scheduling large amounts of processors.
- Where are the classes for each ISA instruction? Where are the execute() methods for the StaticInst class?
- Both the classes and the execute() methods are generated through Python upon building any version of M5. For example, After building ALPHA_SE, they will be located in the build/ALPHA_SE/arch/alpha/ folder. The key files are decoder.hh, decoder.cc (which describe the ISA instructions), and *_exec.cc (which describe the execute() methods). The definitions for both exist in the .isa files found in src/arch/*/isa/, which are processed by src/arch/isa_parser.py to generate the previously mentioned .hh/.cc files.
- Which config files are used for syscall emulation? Full system mode?
- How do I use the sampler?
- Is fast-forwarding supported in SMT mode?
- It is not currently supported. The SimpleCPU doesn't support SMT, so it doesn't support fast-forwarding in SMT mode. However it should be feasible given some hacking on the SimpleCPU or the Sampler.
